Biofuels from Lignocellulosic Material - in the Norwegian Context 2010 – Technology, Potential and Costs

Biofuels from lignocellulosic material - In the Norwegian context 2010 – Technology, Potential and Costs

Project report by: Stud.Techn: Øyvind Vessia

Teaching supervisor: Per Finden

Professional adviser: Øyvind Skreiberg

NTNU, Norwegian University of Science and Technology Faculty of information technology, mathematics and electrical engineering Department of electrical engineering

Autumn 2005 Trondheim 20 December 2005

Preface I would like to thank Per Finden for being very flexible to accept the subject and be my teaching supervisor. A great reward goes to Øyvind Skreiberg, who was professional adviser, for important comments and corrections.

I hope this report can contribute to a more knowledge of biofuels derived from wood, and support the introduction of large scale biofuel production in Norway.

Trondheim, December 2005

Øyvind Vessia

2 Abstract Increased acceptance of climate change induced by human activities and raising oil demand with un-secure deliverance compels the searching for alternative fuels. This study examines the possible automotive fuels produced from biomass, or more specific lignocellulosic material, e.g. wood. The Norwegian forest has an annually growth of 8 times the commercially chopped volume, thus offering a considerable potential of fuel supply. The scope of time is 2010, and conventional engines are assumed used, i.e. no fundamental new infrastructure or engine technology is required. Produced fuels are diesel and ethanol in gasoline blending. The conversion of lignocellulosic material into biofuels is complicated and not yet a commercial business, but the trends towards commercialisation are evident.

The conversion of wood into fuel goes mainly first through gasification or hydrolysis, followed by downstream fermentation or a Fischer-Tropsch reactor. The most important conversion routes are shown below. Routes applicable with lignocellulosic material are marked with red.

The gasification process produces a synthesis gas consisting of mainly CO

and H2. This gas may be fed into a Fischer-Tropsch (FT) reactor where chain growth takes place, producing a wide range of hydrocarbons, including gasoline and diesel. The energy yield of this process is about 50 %, and has been proven in pilot plants. An alternative use of the synthesis gas is to feed it to a fermentation reactor, where a modified bacteria culture digests the synthesis gas and produces ethanol as a product. This technology has received little attention but has been proven in a pilot plant in Arkansas.

The hydrolysis step breaks down the cellulose and hemi-cellulose into fermentable sugars. The fermentation follows conventional technology, but with modifications in order to be able to ferment the C5 sugars. The energy yield of the process is about 36 %. Pyrolysis and HTU (Hydro Thermal Upgrading) are affected by high upgrading costs to enable use in normal automotive engines.

Well to tank (WTT) energy analysis of the biomass to biofuel routes show that biomass farming and transportation have a minor part of the total WTT energy expended. The major losses lie in the energy conversion into a fuel. The Well to Wheel (WTW) emission analysis indicates the possible CO2 reduction potential of fuel switching from conventional fuels to biofuels. The WTW energy efficiency is lower than conventional fuels, as indicated in figure A. The biofuels uses twice the primary energy compared to conventional fuels, but exhaust

3 only 12 % of the CO2. The future option of a hydrogen fuelled car (hydrogen derived from natural gas) with hybrid engine is shown as chain 10. The same car with biomass derived hydrogen is shown as chain 11. It has the same WTW energy efficiency, but exhaust only 13

% of the CO2. A shift towards FT diesel production and later H2 production from biomass offers significant CO2 reductions as shown in the figure (chain 7 and 11).

180 1) DICI Conventional Diesel 160 140 2) PISI Conventional Gasoline 120 4) PISI, 100% Ethanol, 100 hydrolyse, FW 80 7) DICI 100% FT Diesel, 60 FW

40 10) FC hybrid, on-site WTW GHG WTW GHG (g CO2-eq./km) 20 reform, Pipe 4000 km, NG WTW energy (MJ/ 100 km) 0 11) FC hybrid, pipe, central 0 100 200 300 400 500 600 gasification, FW

Figure A: Well To Wheel energy efficiency and CO2-eq emissions for some fuel chains

The most promising technology available today is the production of Fischer Tropsch (FT) diesel through gasification, seen as chain 7 in figure A. It offers high energy efficiency (about

50 %) and low CO2 emissions (reduction of about 85 %). The production of ethanol (chain 4) is less effective but ethanol has a very high octane number and is therefore used as a petrol fuel additive to improve engine performance, typically added as E5 or E10. The use of higher concentrations blends of ethanol such as E85 is possible, but requires small changes to petrol engines. A production of ethanol in Norway assumes exemption from the liquor tax on ethanol.

The economy of FT diesel production is dependent on several factors as scale of plant (> 200 MW thermal), biomass resources at low cost (< 14 €/MWh) and steady predictable operation.

The mineral oil and CO2 taxes are essential to enable profitability. The main barriers are lack of commercial operation experience and access to long-term large amounts of biomass to low cost. The Trysil location is applicable as the area has a large amount of forest. It would still be preferable for a commercial plant of some size to have access to a seaport. A seaport enables access to several biomass resource markets, thus avoiding exertion of market power. It can be difficult to obtain the needed quantity of biomass for commercial operation (>1 TWh annually) at low enough cost in Trysil.

4 1 Table of Contents:

Abstract ...... 3 1 Table of Contents: ...... 5 2 Introduction ...... 10 2.1 Biomass ...... 10 2.2 Feedstock and products ...... 12 2.3 History of biofuels...... 14 2.4 Norwegian conditions and limitations...... 16 2.5 Concluding limitations of study ...... 17 3 Cellulosic biomass – properties and characteristics...... 18 3.1 Norwegian biomass potential for lignocellulosic materials ...... 20 4 Conversion routes and technologies...... 22 4.1 Gasification of biomass into synthesis gas...... 22 4.2 Conversion of synthesis gas with the Fischer Tropsch process ...... 23 4.3 Conversion of syngas with a Bacterium conversion ...... 23 4.4 Hydrothermal upgrading ...... 24 4.5 Pyrolysis...... 24 4.6 Ethanol through hydrolysis and fermentation ...... 26 5 Detailed description of technologies...... 27 5.1 Hydrolysis and fermentation of sugar ...... 27 5.1.1 Pre-treatment ...... 27 5.1.2 Promising pre-treatment technology: Steam explosion ...... 28 5.1.3 Hydrolysis catalysed by cellulase ...... 28 5.1.4 Fermentation and distillation...... 29 5.2 Gasification ...... 30 5.2.1 Gasification reactions...... 30 5.2.2 Types of gasifiers ...... 32 5.2.3 Gas shift and syngas conditioning...... 33 5.2.4 Gas cleaning and catalysts...... 34 5.3 Fermentation of synthesis gas ...... 35 5.4 Fischer- Tropsch reactor fed by syngas...... 37 5.4.1 Historic development ...... 37 5.4.2 Process routes...... 38 5.4.3 Products...... 39 5.4.4 Modelling FT-product distributions...... 41 5.4.5 The basic model: the ASF-distribution with Flory interpretation...... 42 6 Pilot plants and projects ...... 48 6.1 Ethanol producing pilot plants ...... 48 6.1.1 BRI - bacterium fermentation of syngas ...... 48 6.1.2 Ornskoldsvik – Ethanol from wood, through hydrolysis and fermentation..... 50

5 6.1.3 Iogen – Ethanol from hydrolysis of straw...... 52 6.1.4 DOE Bioethanol Pilot Plant ...... 54 6.1.5 BC International Corporation...... 55 6.2 Gasification pilot plants and FT reactors ...... 57 6.2.1 Güssing – gasification, FT ...... 58 6.2.2 Värnamo...... 60 6.2.3 Choren, Fischer-Tropsch production at a pilot plant in Freiberg...... 61 7 Energy Chain efficiencies ...... 65 7.1 Hydrolysis – Fermentation – Distillation - Ethanol ...... 65 7.2 Gasification – Fermentation – Distillation - Ethanol ...... 66 7.3 Gasification – FT synthesis – Diesel/gasoline ...... 67 7.4 Comparison of energy conversion efficiency from well to tank and resulting GHG emissions ...... 68 7.4.1 WTT Conclusion...... 72

7.5 WTW energy efficiencies and CO2-eq. emissions ...... 73 7.5.1 WTW conclusion...... 75 8 Case study: Trysil...... 76 8.1 Biomass resources...... 78 8.2 Capital cost of a FT diesel plant...... 80 8.3 Scale importance ...... 81 8.4 Efficiency importance ...... 81 8.5 Barriers to introduction of biofuel plant in Trysil...... 83 8.6 Conclusion to the case study of Trysil ...... 85 9 Production cost...... 86 10 Conclusion...... 88 11 References ...... 90

Appendix I: Gasifier reactor types and characteristics...... 95 Appendix II, Pilot plants with gasifier ...... 97 Appendix III, Research in the field of biofuels in Norway 2005...... 101

6 Table of figures: Figure 1: Main biomass energy conversion routes [3]...... 10 Figure 2: Biofuel conversion routes...... 13 Figure 3: World and regional fuel ethanol production, 1975-2003 (million litres per year) [4] ...... 14 Figure 4: Crude oil prices vs. ethanol production, 1980-2004 [52] ...... 15 Figure 5: World and regional biodiesel capacity, 1991 – 2003 (million litres per year) [4]...... 15 Figure 6: Investigated paths in this study...... 17 Figure 7: The relation between moisture content and EHV [kWh/m3] [59]...... 19 Figure 8: Commercial roundwood removals (2003) by species of tree, excluding wood fuel for direct burning in stove...... 21 Figure 9: Principles of a fast pyrolysis with fluidized bed [23] ...... 25 Figure 10: Biomass routes that are close to commercialisation and explained in detail ...... 27 Figure 11: The importance of the quantity of added air to the gasifier process [6]...... 31 Figure 12: Types of gasifiers available from manufactures ...... 32 Figure 13: Technology status for biomass gasification for heat and power [7] (own representation) ...... 33 Figure 14: Types of FT reactors [69] ...... 39 Figure 15: Chain initiation ...... 40 Figure 16: Chain growth and termination ...... 40 Figure 17: Product distribution with iron catalyst [19] ...... 41 Figure 18: Product distribution with cobalt catalyst [19]...... 41 Figure 19: A typically theoretic FT synthesis distribution, ! = 0.85...... 43 Figure 20: Product distribution with ASF-distribution and varying growth probability...... 44 Figure 21: Anderson-Schultz-Flory distribution...... 45 Figure 22: Variation of H2/CO ratio (r), holding partial pressure of H2 constant. T = 573 K ...... 46 Figure 23: Variation of temperature in the Song et.al. model, with H2/CO ratio at 2 ...... 47 Figure 24: Process flow diagram of the BRI Energy technology...... 49 Figure 25: Ethanol production integrated in a municipally energy system...... 51 Figure 26: Schematic process design of ethanol production from wood. Figures in ton per ton dry raw material52 Figure 27: The Iogen process...... 53 Figure 28: NREL operated pilot plant process...... 55 Figure 29: BC International Corporation process diagram ...... 56 Figure 30: General process scheme for power production through gasification [57]...... 58 Figure 31: The Güssing process diagram [48] ...... 59 Figure 32: Process scheme for the Värnamo pilot plant [53]...... 61 Figure 33: The process scheme of the Choren Carbo-V® process ...... 63 Figure 34: Energy expended to produce 1 MJ ethanol. Data range: -0.09/+0.10 [65]...... 66 Figure 35: Energy expended to produce 1 MJ ethanol [40],[65],[69]. Data range not available, but the data concerning the gasifier and fermentation is weak...... 67 Figure 36: Energy expended to produce 1 MJ FT diesel (-0.10/+0.11) [65]...... 68 Figure 37: Energy used in biofuel production compared to conventional fuels and GTL ...... 69 Figure 38: Energy conversion efficiency of some common energy chains...... 70 Figure 39: Energy efficiency to electricity or fuel with resulting CO2-eq emissions...... 71 Figure 40: WTW energy efficiency and WTW GHG emissions per 100 km ...... 73 Figure 41: The chopped volume in 2003 and the location of Trysil ...... 76 Figure 42: Use of gasoline and diesel in mobile combustion in Trysil [73]...... 77 Figure 43: Assumed development of gasoline and diesel use in Trysil ...... 77 Figure 44: Catchment area (green) with an average transport distance of 50 km ...... 78 Figure 45: Potential and cost of wood in Trysil within a range of 100 km [79]...... 79 Figure 46: Sensitivity of biomass feedstock price...... 79 Figure 47: Breakdown of investment costs for a IGT once through concept at 367 MW [33] ...... 80 Figure 48: Effect of scale on the production costs [33]...... 81 Figure 49: The sensitivity of conversion efficiency...... 82 Figure 50: Main areas of attention and barriers against ethanol production in Trysil...... 84 Figure 51: Main areas of attention and barriers against FT diesel production in Trysil...... 84 Figure 52: Production cost range of biofuels, middle value as red mark...... 86 Figure 53: Production cost of biofuels compared with production costs of conventional fuels including taxes... 87 Figure 54: Sensitivity of biomass feedstock price...... 89 Figure 55: Process diagram for the Viking pilot plant ...... 97 Figure 56: Viking gasifier at DTU, Copenhagen, Denmark ...... 98 Figure 57: Process diagram for the Arbre BIG-GT project...... 99

List of tables: Table 1: Chemical compositions of common Norwegian wood types...... 18 Table 2: Density of typical Norwegian wood types...... 18 Table 3: Norwegian forest composition and price ...... 20 Table 4: Product composition from pyrolysis and gasification...... 24 Table 5: Gasification reactions and their reaction enthalpy...... 30 Table 6: The most relevant gasification reactions, and their reaction entalphy ...... 30 Table 7: Reactions taking place in the FT reactor...... 38 Table 8: Products from the FT process ...... 44 Table 9: Greenhouse gas equivalence coefficients...... 65 Table 10: Norwegian taxes on conventional petrol and diesel...... 87

Nomenclature: BTL Biomass-To-Liquids: denotes processes to convert biomass to liquid fuels CCGT Combined Cycle Gas Turbine

CH2 Compressed hydrogen CO Carbon monoxide

CO2 Carbon dioxide: the principal greenhouse gas CONCAWE The oil companies’ European association for environment, health and safety in refining and distribution Atm.CFB Atmospheric pressure Circulating Fluidized Bed DICI An ICE using the Direct Injection Compression Ignition technology DISI An ICE using the Direct Injection Spark Ignition technology DME Di-Methyl-Ether DPF Diesel Particulate Filter EUCAR European Council for Automotive Research and Development ETBE Ethyl Tertiary Butyl Ether, a gasoline additive to increase octane rating EHV Effective heating value FAME Fatty Acid Methyl Ester: Scientific name for biodiesel FC Fuel Cell FT Fischer-Tropsch: the process named after its original inventors that converts syngas to hydrocarbon chains GHG Greenhouse gas GTL Gas-To-Liquids: denotes processes to convert natural gas to liquid fuels HHV Higher Heating Value (‘Higher” indicates that the heat of condensation of water is included) HTU Hydro Thermal Upgrading ICE Internal Combustion Engine IGCC Integrated Gasification and Combined Cycle IPCC Intergovernmental Panel for Climate Change LBST L-B-Systemtechnik GmbH

8 LHV Lower Heating Value (‘Lower” indicates that the heat of condensation of water is not included) M Density of wood

N2O Nitrous oxide: a very potent greenhouse gas NREL National Renewable Energy Laboratory NG Natural Gas NOx A mixture of various nitrogen oxides as emitted by combustion sources PISI An ICE using the Port Injection Spark Ignition technology Press.BFB Pressurized Bubbling Fluidized Bed RME Rapeseed Methyl Ester: biodiesel derived from rapeseed oil (colza) SRF Short Rotation Forestry SSCF Simultaneous Saccharification and Co-Fermentation: a process for converting cellulosic material to ethanol Syngas A mixture of CO and hydrogen produced by gasification or steam reforming of various feedstocks and used for the manufacture of synthetic fuels and hydrogen TTW Tank-To-Wheels: description of the burning of a fuel in a vehicle WTT Well-To-Tank: the cascade of steps required to produce and distribute a fuel (starting from the primary energy resource), including vehicle refuelling WTW Well-To-Wheels: the integration of all steps required to produce and distribute a fuel (starting from the primary energy resource) and use it in a vehicle

9 2 Introduction The study aims to point out the available technologies for biofuels (diesel and gasoline/ethanol) from woody biomass in Norwegian context 2010. Woody biomass and its potential and composition is described in chapter 4. The possible routes are described in chapter 5, and some more relevant technologies are explained in more detail in chapter 6.

Chapter 7 looks at relevant pilot plants, and chapter 8 focus at the energy and CO2 abatement efficiencies of the conversion technologies. Chapter 9 looks upon a case study, where the possibilities of a production plant in Trysil is outlined. The production costs are briefly described in chapter 10, and finally the conclusion is given in chapter 11.

2.1 Biomass With rising focus on regenerative energy sources, the potential of modern biomass (biomass harvested with the aim to produce an energy carrier) has gained importance and attention. Biomass is a term for all organic material that stems from plants, trees and crops. Also organic waste and agricultural and forest residues are considered as biomass. The world derives about 11 % of its energy from biomass, this means about 44 exajoules (mostly traditional biomass, as for cooking etc.), but the biomass potential is considerable, counting 2900 exajoules as theoretically harvestable bio-energy. But more interesting is the 270 exajoules that could be considered technically available on a sustainable basis [1]. In the context of rising demand of environmental concerns and with biomass well distributed all around the world, the option of extended use of biomass should be considered seriously. The main biomass energy conversion routes are shown in figure 1 [3].

Figure 1: Main biomass energy conversion routes [3]

This report focuses on biofuels, seen as the third product in figure 1. But in many biomass conversions there is considerable potential of energy savings and better economy through production of more than one product at one site, e.g. production of fuels and heat from a biodiesel plant.

Improving energy security, decreasing vehicle contributions to air pollution, industrial and commercial development of a new industry, and reducing or even eliminating greenhouse gas emissions are primary goals urging governments to identify and commercialise alternatives to the petroleum fuels currently dominating transportation [3].

In recent years, several candidate fuels have emerged, either as ideas, or more developed commercial available fuels like compressed natural gas (CNG), liquefied petroleum gas (LPG) and electricity for electric vehicles. These fuels feature a number of benefits over petroleum, but they are also affected by a number of drawbacks, like costly modifications to vehicles and the development of separate fuel distribution and vehicle refuelling infrastructure. Biofuels have the potential to leapfrog traditional barriers to entry because they are liquid fuels compatible with current vehicles and blendable with current fuels.

The transportation sector represents about 86 EJ/year (2000), or 21 % of the world primary energy consumption, and this share continues to grow. Transportation fuels are today mainly dominated by fossil oil [25].

It is useful with an overview of main reasons for introduction of biofuels:

! Reduced CO2 emissions. Biofuels are principally CO2 neutral, depending on the conversion route from biomass to fuel, and which additives that are being used. ! Decreasing vehicle contributions to local air pollution. Most biofuels have a cleaner burning than common fossil petrol and diesel. But expected development of engines and stricter emissions regime will probably decrease this difference [2]. ! Higher reliability of energy supply. With more sources of fuel, the prices become more stable and shortage is less probable. ! Industrial and commercial development of a new industry, with increased employment and possibilities of development of intellectual capital. With introduction of biofuels follows employment in the whole chain from harvesting, processing and distribution. ! A developed R&D programme on biofuels points out different solution to the way out of fossil oil dependence.

The idea of biofuel is as old as the idea of the vehicle with an engine. When Henry T. Ford first designed his Model T automobile in 1908, he expected ethanol, made from renewable resources to be the fuel. About the same time in Germany, Rudolf Diesel thought that his compression ignition engine would be run on vegetable oils [10].

11 2.2 Feedstock and products The resource base or feedstock of biofuels are diverse, but can be presented in four main groups (mainly adopted from [4]):

! Cereals, grains, sugar crops and other starches can easily be fermented to produce ethanol, which might be used pure or as a blending with normal petrol.

! Cellulosic materials like grasses, trees and different types of waste products and residuals from crops, wood processing, and municipal solid waste, can also be converted into alcohol or synthesis gas, but these processes are much more complex.

! Oil-seed crops (e.g. rapeseed, soybean and sunflower) can be converted into methyl- esters, which can substitute normal fossil diesel, and can be used pure or as a blending.

! Organic waste material, like fish waste (typically for Norway), marine and animal oil can be converted into biodiesel. Mature and organic household waste might be converted into biogas. The availability is often limited, but the resource cost can be negative in some areas with a strict waste regime.

The products at the end of the conversion routes are diverse, but can be divided into five main groups:

! Biodiesel (mainly RME and FAME) ! Alcohols (ethanol/methanol) ! Biogas ! Synthetic fuel (BTL - biomass to liquid) ! Hydrogen

Some of the main routes from biomass to biofuel are shown in figure 2 (mainly based upon [5]):

Figure 2: Biofuel conversion routes

Some comments, abbreviations and explanations to figure 4 ([2],[5]): ! Biodiesel is the diesel made from rapeseeds, soybeans and other sources of oils. Most common is RME (Rape Methyl Ether), and FAME (Fatty Acid Methyl Ether). The production capacity of biodiesel is shown in figure 3. ! Bioethanol is the biofuel mainly produced in Brazil and USA from sugar cane and corn respectively. The production amounts are rising in Europe. ! Biogas is today locally used in small-scale applications, but require new infrastructure and engine modifications. More adaptable in energy systems with natural gas.

! Synthesis gas is a gas mainly consisting of CO and H2. ! The BTL (Biomass To Liquid) can use cellulose as feedstock, the resource potential is considerable, and also at attractive costs. ! Biomethanol is possible to blend with gasoline, but ethanol is preferred. The use of methanol as blending with gasoline is also possible in blends up to 15 % methanol. This was done in Sweden in the early eighties. This study focuses at ethanol blends, though the differences between the two alcohols are small. Methanol drawbacks are: lower energy content, more toxic and it is more corrosive [29], but it might be produced at lower cost than ethanol. In production of biodiesel (FAME) there is a need for methanol, and this methanol should be produced from biomass to keep the use of fossil methanol low. ! DME (DiMethyl Ether) is widely used as propellant and often produced from natural gas. It is possible to use as engine fuel with modified engine technology, but this use has received minor attention, and will therefore not be considered in this study. ! MTBE (Methyl Tertiary Butyl Ether) is an octane enhancer and formerly used in every gallons of petrol in USA (substituted lead as octane enhancer in 1979). It is produced from methanol and isobutylene. A growing number of studies have detected MTBE in ground water throughout the USA. The human health risks are discussed, and an increasing number of states propose the use of ethanol as octane enhancer. MTBE is therefore not considered in this study [30].

13 ! Pyrolysis oil diesel can be a substitute to diesel, and cellulose can be the resource base. There has not been made much research in the field of pyrolysis oil diesel, much because of the upgrading demand, which is affected with high cost. ! HTU-diesel (Hydro Thermal Upgrading) is based upon soaked and rotted biomass. For HTU-diesel there are no studies on energy and greenhouse gas balances. The cost of upgrading to transportation fuel is considerable.

2.3 History of biofuels Today there is only large scale production of ethanol, and this production is mainly located in Brazil and North America. The fuels are produced from sugar cane and corn respectively [4]. All petrol in Brazil has today a blending of 22 % - 26 % of ethanol, and 2 % of petrol consumption is ethanol in USA [2]. The amount of produced ethanol has risen considerably since the start of the Brazilian PRO-ALCOOL programme in 1975. Over the last years has Europe had a rapid growth in ethanol production, but the amounts are still small compared to Brazil and North America. This is shown in figure 3 [4]:

Figure 3: World and regional fuel ethanol production, 1975-2003 (million litres per year) [4]

The production volume of ethanol is linked to the oil price. A dramatic increase in world ethanol production has been seen since 2000, corresponding with rapid increases in the price of oil and uncertainty over the supply of fossil resources [52].

14 Crude Oil Price Ethanol Production US$/barrel 1000 million litres per year $70 35 $60 30 $50 25 $40 20 $30 15 $20 10 $10 5 $0 0 1980 1986 1992 1998 2004

Crude oil ($/barrel) World Ethanol Production

Figure 4: Crude oil prices vs. ethanol production, 1980-2004 [52]

Rising demand for bio-based ethanol has increased the probability that other feedstocks, including lignocellulosic biomass, could become viable options for the biofuel industry [52].

There is also a biodiesel production of some amount, but this is limited compared to ethanol production (about 4 % of ethanol production in 2003). But the increasing production trend, especially in Europe, is clearly visible in figure 5, where the biodiesel capacity is shown:

Figure 5: World and regional biodiesel capacity, 1991 – 2003 (million litres per year) [4]

There is also other biofuels available, as ETBE (Ethyl Tertiary Butyl Ether) blended in petrol in France, or vegetable oil, used in very small extent in Germany and USA [5], and also small

15 local use of biogas. An example is Fredrikstad in Norway, where four busses are fuelled with biogas from the local sewage treatment plant [2].

2.4 Norwegian conditions and limitations Norwegian climate and vegetation as well as other agricultural conditions determine to some extent the biomass potential. The assumed technological situation in Norway in 2010 gives guidance in consideration of possible energy system scenarios. Therefore; in the choice of a biomass route to investigate for Norwegian conditions, there are some questions to consider:

! Which biomass resources are available in large amounts, and to what price? o There are two possible sources of biomass in the Norwegian context [2]: a) Wastes from industry e.g. fish oil from the fish industry, but this is strongly limited resources and do not have the potential to increase the use of biofuels to a large extent in Norway. The cost might be favourable, but the amount small. b) Cellulose based crops (forest) is available in large amounts. The use of energy crops like corn, rape seed etc. is not economic realisable because of climate conditions and expensive labour. The most common resource of biofuel, the RME, is expected to deliver 200-250 kg/da in Norway, and 400 kg/da is expected many places in Germany [2]. The conditions for energy crops are therefore limited to cellulose materials as forest. This resource will not conflict with other area use, as could be a problem for energy crops plantations, where it might be food production. NVE has reported the biomass potential in Norway, and lignocellulosic material counts for 77 % of possible increased use of biomass [81].

! What is expected fuel-infrastructure development in the next years? o The introduction of hydrogen as energy carrier seems to lag in time, and is not expected to be a common energy carrier in the time frame of this report (2010). A locally based use of natural gas might be expected in vehicles like busses or taxis.

! Which advantages lies in Norway in the context of biomass? o Norway has a considerable potential of unused forest, but parts of the potential are located in areas far away from the demand.

! Which technologies are technically available? o Technologies to convert cellulose to biofuels are in the phase of R&D, pre-pilot and pilot phase. The possible routes are through gasification, hydrothermal upgrading (HTU), hydrolysis and pyrolysis of cellulose material

16 ! What kind of implementation is wanted and available in the timeframe of 2010? o The different types of implementation in Norway may be divided into four: a) Blending of normal gasoline with up to 5 % bioethanol, without major changes to energy infrastructure. b) Gasoline blending with higher share of ethanol, requiring moderate engine modifications. c) Blending of diesel and biodiesel/BTL or pure biodiesel/BTL, keeping the quality in line with the European trade standard for biodiesel (EN14214), thus keeping guaranties from carmakers valid. No need of major changes to energy infrastructure. d) Introducing biogas, hydrogen, methanol, or DME requires more or less new infrastructure and modifications or replaced engines with different compatibility with traditional fuel and infrastructure. But it is a feasible solution where a limited vehicle fleet is operated in a certain area, as e.g. busses or taxies in a certain city.

2.5 Concluding limitations of study For this study, located to Norway in 2010, the biofuel feedstock is forest and wood residues. In order to limit the study, and to focus at the resources where the potential of extensive use of biofuels in Norway is available, the study is limited to cellulose material as resource. The aim of the study is to display possible solutions that do not imply major changes to infrastructure or engines, in the timeframe of 2010. The use of biogas, hydrogen, or DME is thereby not considered. MTBE is used as octane enhancer in USA, but likely to be substituted by ethanol, due to environmental issues (groundwater contamination). MTBE is therefore not considered. Methanol1 does have similar properties as ethanol, but the latter has some advantages, thus limiting the focus at ethanol in this study. With the limitations applied, figure 6 reduces to the following routes of biomass conversion:

Figure 6: Investigated paths in this study.

17 3 Cellulosic biomass – properties and characteristics The source of energy and serving point is cellulosic material. For Scandinavian conditions the forests consist of mainly spruce, pine and birch, and these wood types have the chemical composition shown below [24] (weight %, ash included in extractives):

Cellulose Hemicellulose Lignin Extractives Scandinavian Spruce 42 27 29 2 Scandinavian Pine 42 25 28 5 Scandinavian Birch 39 38 20 3 Table 1: Chemical compositions of common Norwegian wood types

Cellulose is the main part of the cell wall, with the elementary formula (C6H10O5)n. It is a highly linear polysaccharide and similar to hemicellulose, but the latter has a more branched structure and is more susceptible to chemical degradation than cellulose. Lignins acts like the bounds in the cells, and gives rigidity to the cell wall. They are complex three dimension polymers of phenylpropane [24].

Biomass contains the elements; carbon (45-55 weight %), hydrogen (5-7 weight %), oxygen (40-50 weight%) and small amounts of sulphur (0-0.05 weight %) and nitrogen (0-1.0 weight %). The carbon and the hydrogen are the combustible components of the wood.

A proximate analysis is often used to determine the amounts of volatile material, ash and fixed carbon in the biomass. The ash content is important for the heating value, as heating value decreases with increasing ash content.

An important distinction in the field of wood processing is made between softwood and hardwood. The different density of the woods has influence on which technology to apply in the processing, as the density may differ considerable between different types of forest. For the same type of forest the altitude, age and location also influence the density variation with as much as +/- 50 kg/m3. Some typical Norwegian densities are given below [59]:

Density* [kg/m3]:

Scandinavian Spruce 380 Scandinavian Pine 440 Scandinavian Birch 500 *kg dry wood per solid cubic

Table 2: Density of typical Norwegian wood types

Spruce is typical softwood, and the birch a typical hardwood. The pine is also considered as softwood.

18 Another important parameter is the moisture content in the wood. As trees are dependent on water to grow, there is always a high content of water in recently chopped wood. As water evaporate considerable amounts of energy is required (2444 kJ/kg water at 25 C), and less energy is available. The moisture content is therefore a major element in deciding the effective heating value (EHV). The effective heating value is defined as the lower heating value (LHV) subtracting the energy of evaporating the moisture content of the wood. The LHV assumes that the produced water is 100 % evaporated. The water might leave the process as liquid water and not as vapour. The resulting energy content is defined as higher heating value (HHV). The LHV has been used traditionally, and serve as the definition of energy content also in this study.

Many biomass pre-treatments start with drying, increasing the energy density. The importance of moisture content is shown in figure 7 [59]:

3000 2900 2800 2700 2600 2500 2400 2300 2200 2100 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 Bark (M=400 kg/m^3) 700 600 Spruce (M=400 kg/m^3) 500 400 Pine (M=420 kg/m^3) 300 Birch (M=500 kg/m^3) 200 100 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 Moisture [%]

Figure 7: The relation between moisture content and EHV [kWh/m3] [59]

At moisture content of 87 % the energy content of the wood is the same as the required energy to evaporate the moisture. The critical limit is 50 -55 % moisture, further increased moisture content above this level lowers the energy content dramatically, as seen in figure 7 [59]. But the moisture content should not always decrease to below a certain limit, as very dry biomass produces a syngas with less H2. Cost increases also quickly with very dry biomass [60].

EHV can be calculated as an approximation with the following formula [kWh/kg]:

EHV" 5.32 # 6.01 $mr [kWh/kg] (3.1)

Where mr is the moisture content, calculated as the relation between mass of water and total mass of wood and water. This is only a linearization of the graph in figure 7. As a moisture content of 88.5 % leads to zero EHV, and biomass with 0 % moisture leads to an energy content of 2128 kWh/m3 for spruce (density = 400 kg/m3).

The higher heating value might be calculated from the molecular composition [59]:

HHV = 0.3491·XC+1.1783·XH+0.1005·XS-0.0151·XN–0.1034·XO–0.0211·Xash [MJ/kg] (3.2)

It is evident how hydrogen and carbon atoms are contributing to the heating value, and how the oxygen content is contributing negatively. It is therefore an important step in some biomass conversion routes to de-oxidize the biomass in order to increase the heating value.

3.1 Norwegian biomass potential for lignocellulosic materials Norway is covered with 38 % forest, and 24 % is productive forest. Yearly is 7.4 mill. m3 chopped and sold for industrial use, and 0.7 m3 is chopped and used as firewood. The yearly growth is 25.4 mill. m3 (increase in forest volume without bark), which is more than 3 times the yearly chopped volume. The price of wood has decreased over the last decades with almost 50 % (calculated with real value NOK) [71]. The unused forest counts 17.3 mill. m3 per year, representing about 120 000 TJ with 50 % moisture. A conversion efficiency of 40 % gives 2730 million kg diesel or 3500 million litre of diesel. The total sale of diesel was 139 million litres [77]. NVE has estimated a potential of totally 160 000 TJ of biomass in Norway [76]. The theoretical potential of substituting fossil fuel is therefore considerable. NVE states a potential of 22 TWh as increased lignocellulosic based biomass use in Norway [81]. The potential is for energy use and with technical and ecological limits applied. A conversion

efficiency of 40 % gives 880 million litre of diesel, a third of yearly consumption of diesel.

The Norwegian forest has the composition shown in the table below. The price of pulpwood is per m3 of solid wood without bark (2003) [70]:

Standing productive forest: [1000 m3]: Pulpwood price [NOK/m3]

Spruce (softwood) 661 532 221 Pine 210 651 160 Broad-leaved 144 790 221 Table 3: Norwegian forest composition and price

But the spruce is the dominating sale product as figure 8 shows

22 %

Pine 1 % Broad-leaved

Spruce

77 %

Figure 8: Commercial roundwood removals (2003) by species of tree, excluding wood fuel for direct burning in stove

One of the main questions left is what quantities can be delivered at low cost to a biofuels plant. A commercial plant requires large amounts of biomass, more than 1 TWh annually, to exploit the advantages of economy of scale. The available biomass potential and cost is therefore a prerequisite for a economic evaluation of a biofuel plant location.

21 4 Conversion routes and technologies This chapter explains the different technologies, estimates future perspectives and indicate the development phase of the technology (R&D, pre-pilot, and pilot). The analysis indicates which technologies that are most advantageous for implementation in Norway, and these are explained in more detail in chapter 6.

4.1 Gasification of biomass into synthesis gas Gasification is the process of gaseous fuel production by partial oxidation of a solid fuel. This means in common terms to burn with oxygen deficit. The gasification of coal is well known, and has a history back to year 1800. The oil-shortage of World War II imposed an introduction of almost a million gasifiers to fuel cars, trucks and busses. One major advantage with gasification is the wide range of biomass resources available, ranging from agricultural crops, and dedicated energy crops to residues and organic wastes. The feedstock might have a highly various quality, but still the produced gas is quite standardized and produces a homogeneous product. This makes it possible to choose the feedstock that is the most available and economic at all times [6].

Gasification occurs in a number of sequential steps [7]: ! Drying to evaporate moisture ! Pyrolysis to give gas, vaporised tars or oils and a solid char residue ! Gasification or partial oxidation of the solid char, pyrolysis tars and pyrolysis gases

Not all the liquids from the pyrolysis are converted to syngas, due to physical limitations of the reactor and chemical limitations of the reactions. These residues form contaminant tars in the product gas, and has to be removed prior to a e.g. a Fischer-Tropsch reactor. Other impurities in the producer gas are the organic BTX (benzene, toluene and xylene (benzene components with one or two methyl groups attached)), and inorganic impurities as NH3,

HCN, H2S, COS and HCl. There are also volatile metals, dust and soot [23]. The tars have to be cracked or removed first, to enable the use of conventional dry gas cleaning or advanced wet gas cleaning of the remaining impurities. There is mainly three ways of tar removing/cracking: thermal cracking, catalytic cracking or scrubbing.

Despite the long experience with gasification of biomass, there are some problems with large scale reliable operation [6]. No manufacturer of gasifiers is willing to give full guarantee for technical performance of their gasification technology. Though they are sold commercially, they are not delivered with the same kind of operational guarantee as e.g. a gas turbine. This shows the limited operational experience and lack of confidence in the technology [7], but in comparison with alternative routes to utilize cellulosic biomass gasification is well proven and one of the possible technologies to be introduced commercially as a major part of the energy route to biofuel. The technology will therefore be presented in more detail in next chapter.

22 4.2 Conversion of synthesis gas with the Fischer Tropsch process The synthesis gas produced from the gasification process can be delivered to a Fischer- Tropsch (FT) reactor, where long hydrocarbon chains are produced and it is possible to obtain large amounts of e.g. diesel.

The FT synthesis is in principle a carbon chain building process, where CH2 groups are attached to the carbon chain. Which reactions exactly taking place and how, is a matter of controversy, as it has been the last centuries since 1930’s [18]. The reaction can be presented as follows [19]:

%&m nCO''(')* n H22 Cnm H n H O +,2

CO'(##'2 H2 CH 2 H 2 O

This reaction is highly exothermic, and to avoid an increase in temperature, which results in light hydrocarbons, it is important to have sufficient cooling, to secure stable reaction conditions [19].

4.3 Conversion of syngas with a Bacterium conversion Another usage of the syngas is the bacterium conversion done by the firm Bioengineering

Resources Inc. (BRI). The anaerobic bacterium clostridium ljungdahlii converts H2 and CO into ethanol. The reactor fermentation vessels are constructed with the aim of short retention time, even at atmospheric pressure, thereby keeping equipment costs low [10]. A distinct advantage of the syngas fermentation route is its ability to process nearly any biomass resource, and the high selectivity of the modified bacteria culture. Expected yields from a grassroots biomass syngas-to-ethanol facility with no external fuel source provided to the gasifier, are 264-397 litres of ethanol per ton of dry biomass fed [56]. This gives an energy efficiency of 39 % with a mean value of ethanol production and fuel properties adopted from [65]

The syngas fermentation approach has received very modest levels of support in the past.

23 Currently, there are only a handful of academic groups working in this area. More people, time, and money are needed if the pace of progress is to increase [56]. The process has interesting aspects and is therefore presented further in chapter 4.

4.4 Hydrothermal upgrading The purpose of the hydrothermal upgrading (HTU), is to convert biomass into “bio-crude”, a liquid fuel with almost the same energy density as fossil fuels. Large amounts of oxygen are removed as CO2 in the process [12]. The HTU process is especially designed for wet feedstock, since drying of the biomass is not necessary. A broad range of feedstocks can be converted. The biomass is treated in water at high pressures in the range of 120 – 180 bar, and temperature range of 300 – 350C. The biomass is under these conditions depolymerised to a hydrophobic liquid fuel called “bio-crude”, which separates from the water. Some gases such as CO, H2, CO2 (90 weight %) and methane is produced, along with water and organic compounds [13]. Half of the biomass is converted to “bio-crude” (weight %), and another 30 weight% is CO2. The thermal efficiency is high, ranging from 70-90 % [12]. An exergy analyse carried out by Zhong (2002) concludes with an exergy efficiency at optimal conditions of 86 % in the produced bio-crude. The bio-crude is different from fossil fuel, mainly through containing more oxygen, having a broad molecular weight distribution and being solid at room temperature [13]. The literature on the use of HTU points out the advantages of the liquefaction of the biomass, and leaves an impression that the use as automotive fuel is a more exotic use of the crude oil. The lighter fractions of the bio-crude might be upgraded to a diesel fuel [31], but as this fraction is limited and introduces another step in the production of automotive fuel, the HTU diesel is not considered as a probable route to biofuel in 2010. This view is supported by the limited focus at HTU as automotive fuel in literature. The aim of the HTU process is to efficient convert the biomass into a product that is more consistent and standardized, with a high energy density and in a condition which is easy to transport.

4.5 Pyrolysis Pyrolysis is the process of thermal degradation in absence of an externally supplied oxidising agent. The products are mainly tar and carbonaceous charcoal, but also lightweight gases, CO and CO2 may be produced in considerably quantities [8]. The products from the pyrolysis are dependent on the residence time and the temperature. Table 4 displays the products (weight %) of different modes of pyrolysis of wood [7]:

Liquid (%) Char (%) Gas (%) Fast pyrolysis Moderate T, short residence time 75 12 13 Carbonisation Low T, very long residence time 30 35 35 Gasification High T, long residence time 5 10 85 Table 4: Product composition from pyrolysis and gasification

The interest in pyrolysis is mostly due to the higher energy efficiency and the logistical advantages of the product. Especially fast pyrolysis has gained importance over the last years [14]. The conceptual fast pyrolysis with a fluidized bed is shown below (adopted from Bridgwater, 1999):

Figure 9: Principles of a fast pyrolysis with fluidized bed [23]

The possibilities to produce automotive fuels from pyrolysis is highly limited, and normally not the aim of the R&D in the field of pyrolysis. The use of bio-oil as diesel engine fuel is limited to the upgrading of the bio-oil and emulsion with diesel. Since the bio-oil is not miscible with hydrocarbons, the use of surfactants is necessary to aid the emulsification with diesel. This is costly and requires considerable amounts of energy. There are also problems with high levels of corrosion and erosion [14]. The use of emulsions is mostly aimed at diesel engines in stationary applications [15], [16] and [7]. The possible routes to automotive fuels are considered complicated, and the pyrolysis products are aimed at logistic advantages, which are far better than that of untreated biomass [23]. The liquid pyrolytic oil is not suited for direct substitution of petroleum fuels due to high viscosity, high oxygen content and the thermal instability of the bio-oil [32]. There are two main routes to an automotive fuel, either through catalytic cracking or catalytic hydro-treatment. The latter is offering a high stability to the bio-oil by removing the oxygen, but the information on hydro-treatment of bio-oils is limited [32]. The process is also affected by high process and equipment costs required to obtain an adequate degree of de-oxygenation. Lots of problems are reported; reactor plugging and almost complete catalyst deactivation [34]. The catalytic cracking is cheaper, but has disadvantages as low fuel quality and high coking (8-25 weight %) [32] Samolada (1998) reported satisfactory gasoline products from pyrolysis oil (fast pyrolysis). The quality meets the EU specifications, but the costs of the upgrading equipment are at present far above any

25 commercial budget. The use of pyrolysis-oil as energy carrier for biomass is therefore not considered.

4.6 Ethanol through hydrolysis and fermentation Sugars and starch amount to 90 % of the produced ethanol today, but they have a high value for food application, and their sugar yield per hectare is very low compared with the most prevalent forms of sugar in nature: cellulose and hemi-cellulose. Lignocellulosic biomass can be converted to ethanol by hydrolysis and downstream fermentation. This process is much more complicated than just fermentation of C6 sugar [11]. The process is still far from being cost competitive with the production of bioethanol from starch or sugar crops [10].

In hydrolysis the cellulosic part of the biomass is converted into sugars, and fermentation converts these sugars to ethanol. To increase the efficiency of the hydrolysis, a pre-treatment step is needed to break down cell structures. Both the pre-treatment and hydrolysis can be configured in many different ways. The pre-treatment is normally chemically catalysed, but both economics and environment drives it towards physical pre-treatment. The hydrolysis is traditionally an acid reliant process, but far better environment conditions favours enzymatic hydrolysis at same cost as acid hydrolysis [11].

Biomass consists of 10 – 25 % lignin, which is no sugar, and therefore impossible to convert into sugars. Lignin is therefore a residue in ethanol production, and often used for power generation. Though it is possible to upgrade lignin to valuable fuel additives, and thereby improve competitiveness of ethanol technology [11].

Hamelinck (2005) selects three different configurations which are short-term, middle term and long term. The short term is based on commercially available or pilot-stage technologies, and the middle term technologies are in pilot stage or promising laboratory stage. The short term has a scope of 5 years and consists of dilute acid pre-treatment, which has environmental and economic disadvantages. Good alternatives are however not available. The hydrolysis of cellulose is done with enzymes. The scale is 500 MW input, and has an overall efficiency of 35 % (HHV) from biomass to ethanol [11]. This configuration is available today.

A review of available technologies and detailed description of the conversions paths from lignocellulosic biomass to ethanol is written by Hamelinck (2005). The energy route through hydrolysis and fermentation to ethanol is seen as a possible future option, and will therefore be explained in more detail in the following chapter.

26 5 Detailed description of technologies Based on chapter 4, there are some routes that are closer to commercial breakthrough than others. These technologies are explained in more detail in this chapter. The diagram of possible routes is now limited to the following:

Figure 10: Biomass routes that are close to commercialisation and explained in detail

5.1 Hydrolysis and fermentation of sugar The use of sugar and starch crops to produce ethanol through fermentation is well known, but has certain limits: The crops has high value for food application and their sugar yield per hectare is very low compared to the most prevalent forms of sugar in nature: cellulose and hemicellulose [7]. The potential of lignocellulosic biomass is therefore considerable larger than crops and starch, and is especially well suited in Northern parts of the world with less sun radiation.

5.1.1 Pre-treatment The purpose of the pre-treatment is to remove lignin and hemicellulose, reduce cellulose crystallinity and increase the porosity of the materials. Pre-treatment technologies are diverse and numerous, but might be categorized in four main groups [35]: ! Physical pre-treatment: o Mechanical pre-treatment o Pyrolysis ! Physical-chemical pre-treatment: o Steam explosion o Ammonia fiber explosion o CO2 explosion ! Chemical pre-treatment: o Ozonolysis

27 o Acid hydrolysis (dilute acid) o Alkaline hydrolysis o Oxidative delignification o Organosolv process ! Biological pre-treatment.

The different pre-treatments have their specific advantages and disadvantages, and are at different stages of development [35]. The choice of pre-treatment technology heavily influences cost and performance in subsequent hydrolysis and fermentation [11]. A review is done by Sun (2002), and also Hamelinck (2005), where the first consider steam explosion as the most commonly used method for pre-treatment. The latter study states that steam explosion is available in 2-5 years, and thus preferred in midterm perspective. The different pre-treatment technologies are well explained in the mentioned papers. Here only steam explosion will be explained in detail.

5.1.2 Promising pre-treatment technology: Steam explosion The wood chips are heated with high pressure saturated steam (7 - 48 bar, 160 – 260 C) for several seconds up to a few minutes. Then the material is suddenly exposed for atmospheric pressure resulting in an explosive decompression. The process causes hemicellulose degradation and lignin transformation due to high temperature, thus increasing the potential of cellulose hydrolysis. 90 % efficiency of enzymatic hydrolysis has been achieved in 24 h for poplar chips, compared to 15 % efficiency without pre-treatment. The factors involved are residence time, temperature, chip size and moisture content. Optimal solution is obtained by either high temperature and short residence time (270 C, 1 min.) or low temperature and long residence time (190 C, 10 min.). Addition of H2SO4 or SO4 in steam explosion can effectively improve enzymatic hydrolysis and lead to more complete removal of hemicellulose [35].

The advantages of steam explosion are low energy requirement compared to mechanical comminution (70 % more energy required) and no recycling or environmental cost. It is considered the most cost effective option for hard wood and agriculture residues, but is less effective for soft wood [35].

5.1.3 Hydrolysis catalysed by cellulase As the pre-treatment is finished, the cellulose is prepared for hydrolysis, meaning the cleaving of a molecule by adding a water molecule [11]:

()C6 H 10 O 5n '( nH 2 O nC 6 H 12 O 6

This reaction is catalysed by dilute acid, concentrated acid or enzymes (cellulase), where the latter has many advantages as: the very mild conditions (pH = 4.8 and temperature 45-50 C)

28 give high yields and the maintenance costs are low compared to alkaline and acid hydrolysis due to no corrosion problems. Enzymatic hydrolysis is viewed by many experts as the most cost effective ethanol production in the long run [11],[35]. The enzymatic hydrolysis is conducted at 70 C, for 1.5 days and gives yields in the range of 75 – 95 % glucose [11]. There are some different ways of process integration of the hydrolysis [68]: ! Enzymatic hydrolysis with glucose fermentation but without the fermentation of pentose ! Separate hydrolysis and fermentation (SHF): The processes occur in different steps, and are suitable for the fermentation of pentose which also takes place in a separate step. ! Simultaneous saccharification and fermentation (SSF): 1-stage enzymatic hydrolysis, but the fermentation of pentose and glucose takes place in different process steps. ! Simultaneous saccharification and co-fermentation (SSCF): 1-stage enzymatic hydrolysis of cellulose and fermentation of pentose and hexoses all in one process step. The upstream hydrolysis of hydrolysis of the hemicellulose takes place in a separate step. The different configurations make it difficult to divide the fermentation and the hydrolysis, but as they may take place in the same reactor the process descriptions are here divided.

5.1.4 Fermentation and distillation A biological process, although generally slower than a chemical reaction have several advantages over chemical catalytic processes, such as higher specificity, higher yields, lower energy costs and greater resistance to catalyst poisoning. The irreversible character of biological processes allows complete conversion and thereby avoids thermodynamic equilibrium relations [36].

A variety of microorganisms, mostly bacteria, yeast or fungi ferment carbohydrates to ethanol under oxygen free conditions. This is a naturally reaction necessary to obtain energy and thereby grow. According to the reactions, the theoretical maximum yield is 0,51 kg ethanol and 0,49 kg CO2 per kg of xylose and glucose [11]:

3C5 H 10 O 5(' 5 C 2 H 5 OH 5 CO2

C6 H 12 O 6('22 C 2 H 5 OH CO2

The conversion of glucose (C6) has been known for at least 6000 years when Sumerians, Babylonians and Egyptians began to perfect and describe the process of making beer from grain (starch). The conversion of xylose (pentose) is more complicated and research has only lately (1980s) obtained success [11]. This issue is still an important R&D field, to increase ethanol yield and thereby enhance chances of commercialisation.

29 The products from the fermentation (often called “beer”) are a mixture of ethanol, cell mass and water. The micro organisms do not allow too high concentrations of ethanol, by 30 C the limit is by about 10 weight%, and decreasing with increasing temperature. First step is to recover the ethanol in a distillation column, where the water remains with the solids. Then a further increase of ethanol concentration is needed. This last step in the conversion route is named distillation and means to concentrate the ethanol and part it from the other products.

5.2 Gasification In a gasifier, the carbonaceous material undergoes three processes. The pyrolysis process occurs as the carbonaceous particle heats up. Volatiles are released and char is produced. The process is dependent on the properties of the carbonaceous material and determines the structure and composition of the char, which will then undergo gasification reactions. Partial combustion occurs as the volatile products and some of the char reacts with oxygen to form

CO2 and CO, which provides heat for the subsequent gasification reactions.

5.2.1 Gasification reactions The complexity of the gasification process is illustrated by the number of reactions taking place, and the considerably number of components in the biomass. The main reactions in the gasification process are listed below [9]:

-1 Reaction: !H298, kJ mol

Volatile matter ! CH4 + C Mildly exothermic

C + 0.5O2 ! CO -111

CO + 0.5O2 ! CO2 -254

H2 + 0.5O2 ! H2O -242

C + H2O ! CO + H2 +131

C + CO2 ! 2CO +172

C + 2H2 ! CH4 -75

CO + 3H2 ! CH4 + H2O -206

CO + H2O ! CO2 + H2 -41

CO2 + 4H2 ! CH4 + 2H2O -165 Table 5: Gasification reactions and their reaction enthalpy

Prins 2005 [6] claims that the following three reactions are most relevant for carbon conversion into gaseous components:

-1 Reaction: !H298, kJ mol

C + H2O ! CO + H2 +131

C + CO2 ! 2CO +172

C + 2H2 ! CH4 -75 Table 6: The most relevant gasification reactions, and their reaction entalphy

30 There is three oxidants to apply; air, steam and pure oxygen. The latter is affected with high economic and energy costs and is not considered useable in commercial applications. Since the use of pure oxygen is expensive, but offering considerable advantages as smaller downstream equipments, lowered compression energy and a higher partial pressure for relevant components for FT, the use of oxygen enriched air combines the advantages in a less expensive medium [23]. The use of steam or air as oxidant agent is a question of exergy use and desired production gas. As shown by Prins (2005), the overall exergy efficiency is almost equal for air and steam, but as steam contains vast amount of hydrogen atoms, this results in higher production rate of methane. Methane is not wanted in the producer gas, as the required synthesis gas to the Fischer-Tropsch reactor is hydrogen and CO. For production of BTL it is theoretically preferred to use air as oxidations agent, but the high content of nitrogen as an inert gas, increases the downstream equipment size and costs [23], and thereby enabling steam or enriched air to be used as oxidant. The use of air is ruled out by some studies, because of the strongly increase in downstream equipment size [60].

The amount of air added the biomass is very important for the composition of the producer gas. More added air as oxidant reduces the efficiency, and increases the yield of gaseous products. This is shown in figure 11, where the energy content of the products is shown as function of the equivalence ratio (ER). A ratio of one corresponds to stoechiometric combustion. ER = 0 corresponds to pyrolysis, ER = 0.25 – 0.50 correspond to gasification and ER > 1 corresponds to combustion [6].

Figure 11: The importance of the quantity of added air to the gasifier process [6]

As seen in figure 11 raises the amounts of gaseous products until a limit of about ER = 0,25. At higher ER more of the gaseous products are burned into sensible heat, and thereby lowers

31 the chemical conversion efficiency, as the energy is wanted as chemical energy in CO and H2 bonds, and not as heat.

5.2.2 Types of gasifiers The types of gasifiers are various, but may be divided into three main groups: entrained flow gasifiers, fluidized bed gasifiers (bubbling/circulating) and fixed bed gasifiers, where the last is subdivided into: counter-current (updraft), co-current (downdraft) and cross-current moving bed. The main differences concern how reactants and products are moved around in the reactor, and the resulting reaction conditions. The reactors may be operated at atmospheric pressure or at higher pressures, but the latter is only available to bubbling or circulating fluidized bed reactors, but at considerable higher cost. The higher cost may be earned downstream due to smaller equipment size and higher reactivity. The main types of gasifiers are shown below [6]:

Figure 12: Types of gasifiers available from manufactures

Bridgwater (2003)[7] has done a review of available gasifiers, and estimated the technology strength and market attractiveness. His findings are summed up and shown in figure 13 below:

Atm = Atmospheric pressure, Press. = Pressurized CFB = Circulating Fluidized Bed, BFB = Bubbling Fluidized Bed

Figure 13: Technology status for biomass gasification for heat and power [7] (own representation)

The conclusion drawn by Bridgwater states that for large scale applications the preferred and most reliable system is the circulating fluidized bed gasifier, while for the small scale applications the co-current fixed bed is the most studied and well suited. Co-current or downdraft gasifiers amount to 75 % of manufactured gasifiers, 20 % is fluidized beds, 2,5 % were counter-current (downdraft) and 2.5 other types [7]. These gasifiers are mostly suited for electricity generation. Downstream equipment as FT reactors or syngas fermentation vessels has different requirements to the syngas than a gas turbine and thus altering the “technology strength” and “market attractiveness” of the Bridgewater review.

Atmospheric circulating fluidized bed gasifiers have been demonstrated as very reliable in the range from some MW to 100 MW, and are also expected to be stable and reliable at higher power ratings. Atmospheric bubbling fluidized bed gasifiers are proven reliable up to 25 MW, but larger reactor size makes up-scaling difficult. On the other hand, they are more economic for small to medium range capacities [7].

5.2.3 Gas shift and syngas conditioning

The produced gas consists mainly of H2, CO, CO2 and CH4. The desired products are in the case of a downstream FT reactor a high yield of H2 and CO. This can be achieved by reformation of CH4 and gas shift reactions, where CO is converted to H2 and CO2. Both processes occur with the help of steam. A reduction of CO2 which decrease the amount of

33 inert gas might also be wanted. A higher reactivity is obtained with lower amounts of inert gas, but the cost may be considerable.

5.2.4 Gas cleaning and catalysts Not all the liquids from the pyrolysis are converted to syngas, due to physical limitations of the reactor and chemical limitations of the reactions. These residues form contaminant tars in the product gas, and have to be removed prior to e.g. a Fischer-Tropsch reactor. The pyrolysis of the solid fuel occur in the temperature range of 300 – 500 C, but as the gasification takes place at higher temperature, the tars in the product gas tend to be refractory and hard to remove by catalytic, thermal or physical processes. This aspect of the tar cracking or removal in gas cleaning is one of the most important technical barriers to implement the gasification of biomass technology [7]. Other impurities in the producer gas is the organic BTX (benzene, toluene and xylene (benzene components with one or two methyl groups attached)), and inorganic impurities as NH3, HCN, H2S, COS and HCl. There are also volatile metals, dust and soot [23]. The tars have to be cracked or removed first, to enable the use of conventional low temperature wet gas cleaning or advanced high temperature dry gas cleaning of the remaining impurities. Cracking or recycle of the tar back to the gasifier is preferred as the tar has a high content of chemical energy [23].

The bottleneck in the gasification process is the gas cleaning. The continual build up of condensable organic compounds (known as tars) in the producer gas may cause blockages, corrosion and reduce efficiency.

There are three basic ways to destroy tars: thermal cracking, catalytic cracking and scrubbing. The thermal cracking operates at temperatures between 1000 – 1200 C where tars are cracked without catalyst, usually by adding steam or oxygen. Drawbacks are low thermal efficiency, soot production and the need of expensive materials [60].

Catalytic cracking consists of a catalyst that decomposes the unwanted hydrocarbons into CO and hydrogen [9]:

%&m Cnm H'-'' nH2 O nCO)* n H 2 +,2 %&m Cnm H'-' nCO222 CO)* H +,2

There are three groups of catalyst: dolomite, alkali and nickel, and these are inserted either as primary catalyst directly in the gasifier, or downstream in an own reactor with the possibility of operation under different conditions than the gasifier [9].

Dolomites are cheap and easily to replace as it deactivates, but it does not reform the methane content of the producer gas, and alone it is not suitable for syngas production for biofuel use.

34 Alkali reduces tar and methane content, but the recovery of the catalyst is costly and difficult. Alkali is not suitable as secondary catalyst. Nickel is an effective and relative cheap catalyst. It is most suitable as secondary catalyst, and functions well in combination with dolomites as primary catalyst [9]. More detailed review of catalysts is available by Sutton (2001). The drawbacks of the thermal cracking are avoided, but the technology is not yet fully proven, and catalyst cost and expenditure are issues of concern [60].

The third possibility is the use of advanced low temperature scrubbing, with an oil-based medium. The tars are subsequently separated from the oil and returned into the gasifier.

Now tars are almost absent and the remaining inorganic impurities are NH3, HCN, H2S, COS, HCl and also volatile metals, dust and soot, which may be removed by conventional low temperature dry gas cleaning or advanced high temperature wet gas cleaning.

The low temperature wet gas cleaning is often applied to the BIG/CC technologies, and consists of a train with cyclone, bag filter and different scrubbers to absorb the contaminations [33]. This cleaning step takes place at low temperature. The advanced high temperature dry gas cleaning is a train with several filters in which the high temperature of the syngas can be maintained, thus offering potential of higher efficiency and lowered operational costs. But as the use of syngas in this study is limited to either fermentation at 37 C, or in a FT reactor at 200 C, the potential energy savings are less apparent [33]. The advanced hot gas cleaning is not yet a commercial process but it is performed in the Värnamo IGCC power plant, as explained later. The hot gas cleaning is mainly aimed at power generation, where the energy savings are easier to utilize.

5.3 Fermentation of synthesis gas Anarobic bacteria are able to grow on syngas components, thus forming acetate and ethanol. The bacteria conversion has the advantages of high selectivity, no thermal equilibrium (because of irreversible ingestion of syngas) and fewer problems with catalyst poisoning [36].

The bacteria culture has to be able to convert CO2, CO and H2 into ethanol. Many of the organisms are either mesophiles or thermophiles with temperature optimums ranging from room temperature to 90°C. A fairly rich media is typically required, but high operating temperatures, low carbohydrate levels, low pH and high CO levels (which are inhibitory to methanogens) reduce the risk of contamination. In contrast to many other syngas based processes, syngas fermentation performance is not tied to a specific ratio of H2 to CO. While the organisms generally prefer CO to H2, both CO and H2/CO2 mixtures can be simultaneously converted. Very little work has been published on the effects of syngas impurities. One would expect some tolerance to sulphur compounds, tars and other impurities, but not enough work has been published to make general statements [56].

35 The bacteria “Clostridium ljungdahlii” is used by BRI Energy, where the reactants are CO2,

CO and H2 reacting in an aqueous phase where pressure is ranging from 0.8-2 bar, and the temperature is 35-37 C [36]. The fermentation has the following reactions [41],[56]:

!G [kcal/mol]

63CO'(' H2 O C 2 H 5 OH4 CO2 -48.7 (5.1)

62H2'(' CO 2 C 2 H 5 OH3 H2O 28.7 (5.2)

Other possible reactions are the production of acetic acid:

!G [kcal/mol]

42CO'(' HO23 CHCOOH2 CO2 -39.2 (5.3)

42H2'(' CO 2 CHCOOH 3 2 HO2 -25.8 (5.4)

The free energy ("G) indicates weather a reaction goes spontaneous at constant temperature and pressure, and is defined as follows [82]:

"G = "H - T"S

Where "H is enthalpy difference, T temperature and "S is entropy difference. A negative "G indicates a spontaneous reaction. From reaction (5.1) it is indicated that CO are preferable in favour of H2, as CO and water reacts easier than H2 and CO2. Typical CO conversion reported in literature is 90 % and 70 % for H2 [56]. The conversion of CO into ethanol has low mass yields, as there is produced about 4 times the mass of ethanol as CO2 as seen in reaction (5.1). The energy balance of equation (5.1) is outlined below:

The LHV of CO is 566 kJ mol-1 [78] resulting in 20.2 MJ/kg. The energy in the water is not considered as water is a common reaction product. One kg CO reacted with water into ethanol results in 0.274 kg ethanol with a LHV of 26.8 MJ/kg for ethanol [65]. This results in a theoretical maximal efficiency of 36,3 %, but this is only valid for equation (5.1), the reaction (5.2) has the opposite characteristics, as indicated below:

The LHV of H2 is 120.1 MJ/kg. One kg H2 reacted as in reaction (5.2) results in 5.75 kg ethanol with LHV of 26.8 MJ/kg. This leads to an theoretical maximum efficiency of 128.4 %. The whole set of reactions has probably a theoretical efficiency between the two.

The ratio between ethanol to acetate produced is dependent upon fermentation reaction conditions. The production of acetic acid leads to a decreased pH, together with a higher concentration of acetate ions. This inhibits the organisms, and in order to avoid further

36 inhibition the organisms switches to ethanol production. The pH is normally kept at 4,5 in ethanol production [56].

With a syngas H2/CO ratio of 2, the reaction indicates that water and ethanol are the only theoretical products, but the ratio is not of major importance as the bacteria prefer CO.

Additionally CO/H2 shift reactions to improve the ratio are thus not necessary.

The ethanol is toxic to the bacteria, resulting in a need to hold the ethanol concentrations below 3 % in the reactor. A detailed description of the bacteria is given by Younesi 2005. The biocatalytic reaction has the advantages of high yields and a very high selectivity. The only products are ethanol, CO2 and water, thus avoiding upgrading, cracking or separating processes of lower grade products.

The technology is proven in a pilot plant in Arkansas, where ethanol is produced from a diverse feedstock for four years. The reaction time from biomass to distilled ethanol has been proven to be short (7-8 minutes) compared to fermentation of sugars, which often last for 1-2 days [40]. The pilot plant is presented in the next chapter. The technology combines two distinct fields of research, namely the gasification of organic material and the knowledge of biochemical conversion through the use of bacteria.

5.4 Fischer- Tropsch reactor fed by syngas Two main characteristics of Fischer-Tropsch synthesis (FTS) are the unavoidable production of a wide range of hydrocarbon products (olefins, paraffins, and oxygenated products) and the liberation of a large amount of heat from the highly exothermic synthesis reactions [56].

5.4.1 Historic development The synthesis of hydrocarbons from CO hydrogenation over transition metal catalysts was discovered in 1902 when Sabatier and Sanderens produced CH4 from H2 and CO mixtures passed over Ni, Fe, and Co catalysts. In 1923, Fischer and Tropsch reported the use of alkalized Fe catalysts to produce liquid hydrocarbons rich in oxygenated compounds — termed the Synthol process [69].

The development of pressurized FT synthesis goes 80 years back, and starts about 1925 in Germany. Here the experiments took place in Franz Fischer’s laboratory at the Kaiser Wilhelm Institute for Coal Research, and developed to an industry with 600 000 tons per year in 1945. At those times strategic reasons for liquid fuel production from coal exceeded economic aspects. In the last decades the interest in FT synthesis has changed as a result of environmental demands, technological developments and change in fossil energy reserves. A good example is the “oil-age” from 1955 – 1970 with plenty of cheap oil supply and as a result only a marginal interest in FT synthesis [17]. High oil prices increase the focus at alternative fuels, likewise as carbon dioxide concentration concern arises, being related to

37 global warming, the focus at new technologies rises. Today the driving forces are environmental concern, but also higher oil price, limited oil reserves and increased focus at stranded gas.

5.4.2 Process routes

The FT synthesis is in principle a carbon chain building process, where CH2 groups are attached to the carbon chain. Which reactions exactly taking place and how, is a matter of controversy, as it has been the last century since 1930’s [18]. The resulting overall reaction can be presented as follows [19]:

%&m nCO''(')* n H22 Cnm H n H O +,2

o CO'(##'2 H2 CH 2 H 2 O ."#HFT 165 kJ / mol

There is also other reactions taking place in the reactor, but the detailed behaviour of the reactions is not known and is a theme of controversy. The reactions reported are (adopted from [37]):

Reaction: Reaction enthalpy: !H300 K [kJ/mol]

CO + 2H2 " -CH2- + H2O - 165.0

2 CO + H2 " -CH2- + CO2 -204.7

CO + H2O " H2 + CO2 -39.8

3CO + H2 " -CH2- + 2CO2 -244.5

CO2 + 3 H2 " -CH2- + 2H2O -125.2 Table 7: Reactions taking place in the FT reactor [37]

These reactions are highly exothermic, and to avoid an increase in temperature, which results in lighter hydrocarbons, it is important to have sufficient cooling, to secure stable reaction conditions [19]. The total heat of reaction amounts to ca. 25 % of the heat of combustion of the synthesis gas [37], and lays thereby a theoretical limit on the maximal efficiency of the FT process.

The reaction is dependent of a catalyst, mostly an iron or cobalt catalyst where the reaction takes place. There is either a low or high temperature process (LTFT, HTFT), with temperatures ranging between 200-240 °C for LTFT and 300-350 °C for HTFT [20]. The HTFT uses an iron catalyst, and the LTFT either an iron or a cobalt catalyst. The different catalysts include also nickel and Ru based catalysts, which also have enough activity for commercial use of FT. But the availability of Ru is limited, thus forcing a high price. The nickel based catalyst has high activity but produces too much methane, and additionally the performance at high pressure is poor, due to production of volatile carbonyls. This leaves only

38 cobalt and iron as practical catalysts, and this study will only consider these two. Iron is cheap, but cobalt has the advantage of higher activity and longer life, though it is on a metal basis 1000 times more expensive than iron catalyst [18].

For large-scale commercial FT reactors heat removal and temperature control are the most important design features to obtain optimum product selectivity and long catalyst lifetimes. Over the years, basically four FT reactor designs have been used commercially. These are the “multitubular fixed bed”, the “slurry” or the “fluidized bed” (with either fixed or circulating bed) reactor. The fixed bed reactor consists of thousands of small tubes with the catalyst as surface-active agent in the tubes. Water surrounds the tubes and regulates the temperature by settling the pressure of evaporation. The slurry reactor is widely used and consists of fluid and solid elements, where the catalyst has no particularly position, but flows around as small pieces of catalyst together with the reaction components. The slurry and fixed bed reactor are used in LTFT. The fluidized bed reactors are diverse, but characterized by the fluid behaviour of the catalyst. The literature of FT contains details of the reactors, and Dry (2001) is one source of more detailed information [18]. The fluidized bed reactor is used in HTFT.

Figure 14: Types of FT reactors [69]

5.4.3 Products

Figure 15 shows how the chain building process starts, where CO reacts with H2 to CH2, with

H2O as a by-product.

Figure 15: Chain initiation

For a theoretical optimal and stoichiometric chain growth, there is a need for 2 hydrogen molecules for each CO molecule. This relation is the H2/CO ratio and differs in the range between 1.7 : 1 and 3 : 1 [37]. The influence of the ratio is explained later in this chapter.

The FT process produces different olefins and paraffins of different length. The process is basically a chain-building process, where the chain either gains length by adsorbing another CO group, or terminates and leaves the catalyst as either paraffin or olefin. This is graphically shown in figure 16 [20]:

Figure 16: Chain growth and termination

Figure 16 shows that there are two possibilities; either terminate to a paraffin (right side) or a olefin (arrow to the left), or to grow further with the absorption of CO and H2 as CH2.

Two examples of product distributions are given below, the first with iron catalyst, and the second with cobalt catalyst. The experiments have been carried out at the Technical University of Vienna. The reactions take place in a bench scale FT reactor (~250 ml reactor

40 volume) [19]. The x-axis indicates the chain length, while the y-axis shows the percentage on weight basis.

Figure 17: Product distribution with iron catalyst [19]

The reactions with iron catalyst are conducted with 30 bars and 280 C. The iron catalyst provides high selectivity in the important interval between C10 –C18, which means a high yield of diesel.

Figure 18: Product distribution with cobalt catalyst [19]

The cobalt catalyst provides a higher growth probability, as heavier products are produced. The reaction conditions were 30 bar and 240 C. The heavier and longer hydrocarbons can be easily cracked into desired products.

The probability of chain growth, !, is assumed to be constant, and this assumption fits well with many experiments done with FT synthesis. With a constant probability of chain growth, the mathematical expression of the product distribution is easy to obtain, which will be explained in the following sub-chapter.

5.4.4 Modelling FT-product distributions There have been many attempts to model the product distributions of the FT process. As the knowledge of the process is limited, also the modelling of the product distributions is not

41 accurate. There are deviations between inspected product distributions and the different models when the conditions are changed. But there is an agreement in literature that the distributions follow some sort of exponential function, with the probability of chain growth as an important factor. The methodology is mainly divided into a kinetic approach and a thermodynamic approach. The best known model of the latter kind was developed in the early years of FT-synthesis, where a constant probability of chain growth was assumed. This model is called the “Anderson-Schultz-Flory” (ASF) [21],[22] distribution model.

5.4.5 The basic model: the ASF-distribution with Flory interpretation The ASF distribution is only valid when there is a constant probability of chain growth. The reaction is then a one-by-one addition of monomer to a growing chain.

A chain with i carbon atoms has the probability as defined in equation (5.5). Each step has the probability of !, and i-1 growing steps results in the probability !i-1:

i-1 Pi-1 = !1 * !2 * !3 * …..* !i-1 = ! (5.5)

This leads to the following equation for the probability of a hydrocarbon of length i to exist (the interpretation is adopted from Flory [22] (1936)):

i-1 2 Pi = ! (1 – !) (5.6)

The second power appears because each hydrocarbon has two un-reacted potential linkages in each end of the chain. In between the two ends there are i-1 carbon linkages, each one occur with a probability of !. Therefore the probability of termination of the carbon chain has a probability of 1 - !, and the chain has to be terminated in both ends of the chain, therefore (1 – !) to the power of 2.

Since there are i different configurations, the probability of any of the i’th configurations are given by:

i-1 2 wi = ! (1 – !) * i (5.7)

n 0//i#12(1 - )$" i 1 n "1,2,3...n (5.8) i"1

The wi is equal the weight fraction, when no molecule is eliminated in the condensation process (typically water).

In order to locate the i value with the highest wi:

42 1 w i )²(1( i#1 i i#1 //// "$'#" 0)ln (5.9) 1 i

Solutions of equation (5.9):

wmin = # (! < 0 ) wmax = -1 / ln !

For typical ! values; 0.7 < ! < 0.9, the hydrocarbons with the highest mass fraction is in the range from propane to petroleum products. A typical example is given in figure 19.

16%

14% Mol% Weight% 12%

10%

molar and weight distributon 2%

0% 11121314151 Carbon Number

Figure 19: A typically theoretic FT synthesis distribution, " = 0.85

The weight distribution in figure 19 shows similar characteristics as the weight distribution adopted from experiments with cobalt catalyst in Vienna in figure 18.

Often a higher concentration of some sorts of hydrocarbons is wanted, which might be achieved by changed reaction conditions. Nevertheless; the product range is wide and infected with uncertainties, due to lack of knowledge of the details of the process and of the kinetics of the reaction. Since the different products have quite different characteristics such as boiling point, physical state at ambient temperature and thereby different use and ways of distribution, often only a few of the carbon chains is wanted. As an example the LTFT is used when longer carbon chains are wanted, because lower temperature increases the portion of longer chains. But too low temperature is not wanted, because of reduced activity. The names used in literature for the different groups of chains are shown in table 8.

Carbon number: Name:

C1-C2 SNG C3-C4 LPG C5-C10 Petroleum C5-C7 Light C8-C10 Heavy C11-C20 Middledestillate C11-C12 Kerosine C13-C20 Diesel C21-C30 Softwax C31-C60 Hardwax

Table 8: Products from the FT process

When the wanted products are shorter carbon chains, e.g. petroleum, the longer ones might be cracked into shorter chains.

Product distribution with the ASF model for different growth probabilities gives the following distribution as percentage of total product weight:

100 % C31-C60 Hardwax 80 % C21-C30 Softwax C13-C20 Diesel 60 % C11-C12 Kerosene C8-C10 heavy pet. 40 % C5-C7 Light pet.

Weight distributionWeight 20 % C3-C4 LPG C1-C2 SNG 0 % 0.7 0.75 0.8 0.85 0.9 0.95

Alfa value (chain grow th probability)

Figure 20: Product distribution with ASF-distribution and varying growth probability

Another illustration of the same phenomenon is adopted from [56], which is also based on the

ASF distribution. Be aware that C9 – C11 is counted twice, in both gasoline and diesel:

Figure 21: Anderson-Schultz-Flory distribution.

The yield of diesel is therefore highly dependent on the chain growth probability, which again is dependent on pressure, temperature, feed gas composition, catalyst type, catalyst composition and reactor design [56]. The desire to increase the selectivity of some favourable products leads to a need of understanding the relation between reaction conditions and chain growth probability, which in turn request a mathematical expression for the growth probability in order to make a suitable model of the process. The different attempts to model the growth probability, !, have resulted in some models that are regarded in literature as appropriate to describe the product distribution. Two will be presented here to show the influence of temperature and partial pressure

Lox (1993) presents a model for an iron catalyst, that are often sited or used as reference in literature. The results are well documented. The variables are partial pressure of CO and hydrogen [26]. Out of 11 models for !, a model named ALII in the paper is the best-fitting, and this model is also one of the simplest out of the 11 models [26]:

$ Pk / " HC1 CO ' ' kPkPk 1 COHC 5 HHC 2 HC 6

-5 -6 -6 With kHC1 = 1.22 * 10 , kHC5 = 1.05 * 10 and kHC6 = 2.36 * 10 , with corresponding t- statistic at 29, 36 and 27, which means that the values are all important parameters for a well fitting regression. The values are valid at 573 K (300 °C), as an average of the temperature range investigated. The partial pressure is in bar. To see the importance of the partial

45 pressures, the product distributions are plotted for different pressures. The partial pressure of hydrogen is held constant, while the partial pressure of CO is increased. The ratio (r) is the number of hydrogen atoms per atom of CO. Normal feeding in a FT reactor is a ratio of 2.

18% p(CO) = 1, p(H2) = 5, r = 5 16% p(CO) = 2, p(H2) = 5, r = 2,5 14% p(CO) = 2,5, p(H2) = 5, r = 2 12% p(CO) = 4, p(H2) = 5, r = 1,25 10% p(CO) = 5, p(H2) = 5, r = 1 8% Weight % Weight p(CO) = 10, p(H2) = 5, r = 0,5 6%

4% C-number 2%

0% 1 6 11 16 21 26 31 36

Figure 22: Variation of H2/CO ratio (r), holding partial pressure of H2 constant. T = 573 K

It is clear from figure 22 that a higher yield of CO in the feeding of the reactor leads to an increase in the chain growth probability !, thus resulting in a increased portion of heavier hydrocarbons. This is expected from the fact that heavier hydrocarbons need more CO per H2, to build longer chains. Ethane for example need 2 C, and 6 H, but propane needs only 12 H at 5 C, giving a ratio of 2,4 in comparison with 3 for ethane. A too low portion of hydrogen lowers the activity and is therefore not wanted. A ratio much lower than 2 is not practically realistic, as a lower concentration limit of H2 is required to have a acceptable reaction rate.

The dependence of temperature is shown by e.g. a model presented by Song (2004). The paper investigates the relation between process parameters and reactor characteristics. The model consists of a linear temperature dependence, which is obtained by fitting the equation with experimental data from the literature [27]:

% y & / ") A co ' B*45# 0039,01 23T # 533 ) ' yy * + H 2 co ,

Where A = 0.2332 +/- 0.0740 and B = 0.6330 +/- 0.0420. T is temperature in Kelvin, and the yco and yH2 are concentrations of the feed gas.

46 The -0,0039 is obtained by fitting the equations with experimental data summarized by Van der Vaan and Beenackers 1999 [28]. This gives the following distributions for different temperatures, where the concentrations of CO and hydrogen are kept at a ratio of 2:

16% T=180 °C 14% T=200 °C 12% T=220 °C 10% T=240 °C 8% T=260 °C

Weight % Weight 6% T=280 °C 4% C-number 2% 0% 1 6 11 16 21 26 31 36

Figure 23: Variation of temperature in the Song et.al. model, with H2/CO ratio at 2

It is clear from figure 23, that lowering the temperature increases the production of heavier hydrocarbons, and for production of heavier products the reaction temperature is of crucial importance. As the FT reaction is strongly exothermic it is a challenge to cool the reactor enough to enable production of long hydrocarbons. The reaction needs a certain amount of energy (measured as temperature) to start and maintain the reaction. It is therefore a lower limit of temperature around 180°C. The low temperature operation (LTFT), operates at temperatures ranging from 180 °C to 240 °C.

47 6 Pilot plants and projects There are some pilot plants producing ethanol, petrol or diesel from lignocellulosic material. Some are presented here with operational data, experiences and future plans of commercialisation. The different technologies used are outlined, and a short description of the process is given.

6.1 Ethanol producing pilot plants First the ethanol producing facilities are presented. They are: ! Bioengineering Resources Inc. (BRI), using fermentation of syngas ! EthanolTeknik (ETEK) in Ornskoldsvik, Sweden, using hydrolysis and fermentation. ! Iogen, Canada, using hydrolysis and fermentation of straw. ! National Renewable Energy Laboratory (NREL) in Colorado, using hydrolysis and fermentation of different feed stocks. ! BC International, Louisiana, specialised in hydrolyse of pentose (C5 sugars).

6.1.1 BRI - bacterium fermentation of syngas The pilot plant in Arkansas has been operational with the complete ethanol production cycle since November 2003, when a prototype Consutech gasifier was added to the fermentation reactor. The pilot in Arkansas has produced ethanol in four years. The technology is currently at the point of commercialization and BRI will begin the construction of their first commercial plants within the next four-six months. The references used are the webpage of BRI Energy [39], the report of Forest Sector Table [41] and correspondence with BRI Energy [40].

Technology BRI uses a two-stage gasifier that raises the syngas temperature as high as 1370 C (2500 oF) in the second stage to enable cracking of any heavy hydrocarbons to CO and H2, maximizing the ethanol yield, thus using a thermal cracking. The information given about the gasifier is limited, but it is provided by Parson Ltd, and BRI Energy states that: “There are hundreds of these units in operation with a demonstrated reliability of 95 percent.”

The hot producer gases are then cooled to 37 C (98o F), and introduced into the biocatalytic reactor where ethanol is produced. Here the modified bacteria culture: “Clostridium ljungdahlii” is introduced. A detailed description of the bacteria is given by Younesi 2005. Nutrients are added to provide for cell growth and automatic regeneration of the biocatalyst. The reactions are as follows [41]:

63CO'(' H2 O C 2 H 5 OH4 CO2

48 62H2'(' CO 2 C 2 H 5 OH3 H2O

With a syngas H2/CO ratio of 2, the reactions indicate that water and ethanol are the only products. The official webpage of BRI energy states that the “Clostridium ljungdahlii” only produces ethanol, water and hydrogen, weather this hydrogen is merely excess synthesis gas or a product of the “Clostridium ljungdahlii” bacteria is unclear. As the ethanol is toxic to the bacteria there is a need to hold the ethanol concentrations below 3 % in the reactor.

A dilute, aqueous stream of ethanol is continuously removed through a membrane that retains cells for recycle to maximize reaction rates. Anhydrous (without water) ethanol is produced by conventional distillation followed by a molecular sieve, using the waste heat from the process. Water, with nutrients, is recycled from the distillation bottoms back to the biocatalytic reactor. With ambient temperature and pressures a fermentation time of a few minutes have been achieved. The process is shown in figure 24:

Figure 24: Process flow diagram of the BRI Energy technology.

The bacterial culture is anaerobic and dies when exposed to air. The BRI Energy states at their webpage that: “The process creates no environmental or health hazards, ground or water contamination, and minimal air emissions. Its residue is a non-hazardous ash.”

49 When biomass is used to co-produce ethanol and electricity, significant reductions in greenhouse gas emissions can be achieved.

Feedstock Each module of the BRI technology is able to handle 250 – 300 ton material each day. The BRI process will gasify any carbon-based material whose moisture content is less than 40% (by weight). BRI claims that: “Validation tests have shown that feed-stocks need not be chipped shredded or sorted to remove metal and glass, and that they can be blended. Any mixture of plastics, tires, manure, paper or yard wastes, construction debris, furniture, hazardous wastes, crop residues, timber slash, etc., can be converted into synthesis gas, and then to ethanol. Only the inorganic fraction is not converted. For example, sewage sludge and used tires could be blended to reduce the average moisture content to 40 % or less.” [40]

Efficiency The efficiency of the process is not well documented, as it is highly feedstock dependent and literature on the bacteria conversion of syngas is highly limited. BRI Energy states a general output of 322 litre of ethanol per ton of biomass. Assuming average lignocellulosic biomass with an EHV of 4.2 kWh/kg, calculated from equation (2.1) with moisture content of 20 %, the efficiency is 45 % (LHV of ethanol is 26.8 MJ [68], and the density is 789 kg/m3). A reference used by the NREL in [69], states an efficiency of 35 % (Putsche).

Conclusion The fermentation of syngas into ethanol is an interesting technology that may avoid the syngas purity demand, required for FT diesel production. The experience is highly limited, as reflected in the limited literature on the field. The costs are not available, but a commercial ethanol plant is planned. The BRI technology is suited in Arkansas, and research is done at some universities in the USA (Arkansas, Mississippi, Oklahoma, Michigan and Iowa [69]). The research started in the eighties, but was limited to a few institutions. More people and resources have to be put into this technology to enable an increased pace of progress.

6.1.2 Ornskoldsvik – Ethanol from wood, through hydrolysis and fermentation In the northern parts of Sweden, four different regional energy companies started a company called ETEK (EthanolTeknik) The pilot plant started operation in autumn 2004, and had by spring 2005 produced the first litre of ethanol. The purpose of the pilot plant is to achieve knowledge. The pilot plant is a fully furnished factory, but will not produce ethanol for commercial purposes. It will have a production capacity of only 200 m3 of ethanol per year if it was run continuously. This implies a feedstock of 2 ton each day, producing 400 – 500 litre ethanol per day. The pilot plant will be a research and development centre in co-operation with Lund's University, Chalmers, Umeå University, Mid Sweden University and others. The

50 references are: ECN [42], the webpage of ETEK [44], Lindstedt [38] and Lindstedt [43]. Ethanol production is seen as a possible integrated part of the municipal energy system as shown in figure 25, which shows a solution for a municipally with about 60 000 inhabitants.

Figure 25: Ethanol production integrated in a municipally energy system

The integrated solution may increase the overall energy efficiency as the different energy qualities are used were it is the most adequate and gives the highest yield.

Investment and O&M cost The investment costs is about 12 million € and the annual running cost about 1.3-2.0 million € depending on the research program [43].

Technology for Ethanol production Several process alternatives for hydrolysis of cellulose materials have been evaluated by ETEK. Diluted acid in two steps and a third enzyme step is seen as the most suitable for softwood. The pre-treatment of softwood is more difficult than for hardwood and straw as probably just one step of diluted acid is necessary. The pre-treatment technology chosen by ETEK is the counter current shrinking bed technology developed by NREL.

The process can be shown as follows:

Figure 26: Schematic process design of ethanol production from wood. Figures in ton per ton dry raw material

Feedstock Softwood is the feedstock with biggest potential in Sweden for ethanol production. Softwood residues from harvesting or from sawmills and other wood-based production units can be used. Hard wood residues and cultivated energy crops could also be interesting feedstocks in Sweden. Cultivated energy crops mean mainly salix (willow) and reed canary grass.

Conclusion The use of lignocellulosic material to ethanol production gains much attention in Sweden, reflected in the comprehensive research and the establishment of a pilot plant. The emphasis in biomass utilisation and fuel production in Sweden should not be ignored in Norway, as there are many similarities in feedstock potentials and socio-economic conditions. The liberalised energy sector attaches the energy flows of the neighbouring countries, thus introducing somewhat similar conditions of energy production.

6.1.3 Iogen – Ethanol from hydrolysis of straw Iogen is a Canadian company whose predecessor companies were founded in the 1970's. The company's initial research was on the steam explosion process for straw and wood to increase the digestibility of the feedstock as a source of animal feed. The impetus for the work was the skyrocketing grain costs of the early 1970's. Since that time the company has grown and expanded its research into the production of ethanol from lignocellulosics and the production and marketing of enzymes for a variety of applications. Iogen is Canada's only industrial

52 enzyme manufacturer. The references are: Mc Cloy (1999) [41], ECN (2003) [42] and the webpage of Iogen [45].

There are 65 people on staff at Iogen, including 20 to 30 in research and development. The key staff members have been with the company for over ten years. Iogen has owned and operated a fully integrated pilot plant in Ottawa since 1985. The facility includes pre- treatment, hydrolysis, fermentation, distillation, and co-product recovery stages. The pre- treatment can handle 40 ton a day, and the maximum yield of ethanol is 3 million litres a year.

Technology The Iogen process is an enzymatic hydrolysis process for converting lignocellulosics to ethanol. The unique aspects of the technology include the steam explosion pre-treatment that was pioneered by Iogen, and the proprietary enzymes developed, manufactured, and marketed by Iogen. The cellulose hydrolysis is an expensive but effective option and not economically feasible for all ethanol producers. Iogen’s advantage is that they are producing this enzyme themselves. Iogen has patents in Canada and other countries for aspects of both the steam explosion and enzyme production. The process is shown schematically in figure 27:

Figure 27: The Iogen process

Feedstock The Iogen process is currently suitable for agricultural residues such as wheat straw and corn straw. Hardwood residues are also a suitable feedstock. A single step pre-treatment process for agricultural and hardwood residues can produce a material that can be efficiently hydrolyzed by the enzymes. The pre-treatment process is not as effective for separating the lignin of softwoods from the cellulosic material. Higher levels of enzymes are required and the production and capital costs are also higher. The hydrolysis of softwood done at ETEK’s pilot plant in Sweden uses a three step hydrolysis, but the softwood is dominant in Sweden. Iogen has no plans to do further work on optimizing the pre-treatment of softwoods at this

53 time. They believe that there are sufficient agricultural feedstocks available in Canada that is suitable for their process and that it is not necessary to look at softwoods now.

The process will produce lignin as a co-product. The relatively mild pre-treatment process employed should provide a lignin that can be utilized as a starting material in other processes. In the 1980's Iogen did a substantial amount of work looking for high value markets for the lignin produced by their process. The fall back position is to utilize lignin as a fuel to produce steam or electricity. This use yields a very low price for the lignin.

Conclusion Iogen is one of the more credible organizations operating in the lignocellulosics to ethanol field, as they has long operational experience with their pilot plant. Unfortunately for most of the forest sector, Iogen's technology is not currently suited to the softwood residues that are the primary feedstock of interest as most softwood is chopped in Norway. The development of a pre-treatment process that produce both cellulose and hemi-cellulose that could be enzymatically hydrolyzed economically, would allow the Iogen process to be commercialized also for softwoods. A high value market for lignin produced from softwoods could also make the process more economic. The technology is less interesting for Norwegian conditions as long as hardwood is the only feedstock, since most forest and forest residues in Norway are softwood.

6.1.4 DOE Bioethanol Pilot Plant The pilot plant is operated by the National Renewable Energy Laboratory (NREL) in Golden, Colorado, and is aimed at testing bioprocessing technologies for production of ethanol or other fuels or chemicals from cellulosic biomass. The references are: ECN (2003) [42] and the webpage of NREL [47].

Technology The facility is prepared for a variety of technologies, thereby offering a broad range of possibilities to researchers and scientist with new ideas. The main route form cellulosic material to ethanol goes through pre-treatment, hydrolysis and fermentation. But the critical pre-treatment may be adjusted as the project partner wants. The pilot plant offers three different pre-treatment technologies; commercial dilute acid, counter current shrinking bed like the technology used by ETEK, and finally the steam explosion. The process combines the saccherification and the fermentation in one vessel, which is considered as state of the art [11], this technology is often referred to as SSCF. The advantages are among others the avoidance of product inhibitors associated with enzymes, since the presence of glucose inhibits the hydrolysis. This is avoided as the glucose is immediately fermented to ethanol. This technology was not chosen by ETEK, and they state at their webpage [44] that the technology is not ready yet.

Figure 28: NREL operated pilot plant process

Conclusion The NREL pilot plant is maid for research purposes, to catalyse R&D in the field of ethanol production from lignocellulosic material. Many companies are collaborating with NREL, and doing research at the pilot plant in California. The establishment of the pilot plant gives another example of the increased focus at biofuels derived from cellulosic material.

6.1.5 BC International Corporation BC International Corporation (“BCI”), incorporated in 1994 in Delaware, is a privately held company with its corporate headquarters in Dedham, Massachusetts. The references are: Mc Cloy et.al. (1999) [41], ECN (2003) [42] and the webpage of BC International Corporation [46].

General data BCI has demonstrated the efficiency of its technology in two pilot plants, and it is now putting together a team of engineers and contractors and completing the development of a commercial scale facility in Jennings, Louisiana, that will produce ethanol from sugarcane bagasse. BCI will then expand its business through the construction, ownership and operation of additional ethanol production facilities, participation in joint ventures, and domestic and international licensing of its technology. BCI is engaged in the development of projects in California that will use rice straw and wood wastes as feedstocks, and it has a technology transfer arrangement in place for the application of its technology in Asia.

Its second state-of-the-art pilot plant, which is sized to process about 500 tons of cellulosic biomass feedstock per year, has been operating at its corporate research facility in Jennings, Louisiana, for the last four years. BCI’s techniques have resulted in consistent and reliable organism fermentations, achieving average ethanol yields of over 90%.

Technology In 1995 BCI secured from the University of Florida an exclusive, worldwide license to commercialize a new technology. Through continued research and development at the University of Florida and in-house at BCI, as well as through technology acquisition, BCI has developed a technology to release the sugar potential of cellulose and hemicellulose and ferment into ethanol both the glucose and the non-glucose sugars in cellulosic biomass. BCI’s technology is based on the metabolic engineering of microorganisms. The key element of BCI’s technology is genetically engineered strains of E. coli bacteria, known as KO11, that are capable of fermenting into ethanol essentially all of the sugars released from all types of cellulosic biomass, thus enabling BCI to achieve the required efficiency to make the process commercially feasible.

The process includes two steps hydrolysis and a separate fermentation of xylose (C5 sugars), as shown in figure 29:

Figure 29: BC International Corporation process diagram

Feedstock BCI’s technology can convert almost any type of cellulosic biomass material to ethanol.

Conclusion The major advantage of the BC process is the genetically modified E.coli bacterium that is able to convert also pentose/xylose into ethanol. That is particularly important for agriculture and hardwood residues, but also has some impact on softwoods. The drawback with this process, and specially the use of dilute acid hydrolysis, is the vast amount of residue material.

The production of alcohol through acid hydrolysis implies at least 0.1 kg H2SO4 per kg ethanol produced [42]. A more efficient pre-treatment with less use of acid or enzymes would greatly decrease the waste production. The two stage hydrolysis demands more acid than the simpler one stage hydrolysis performed by Iogen. But the latter does not enable fermentation of the xylose, thus not enabling the utilisation of the advantages of the modified E.coli bacteria.

6.2 Gasification pilot plants and FT reactors At this time (2005) only one company is offering a commercial Fischer Tropsch diesel producing facility, but many installations have experience with gasification, which is the crucial pre-treatment before a FT reactor. Essential is the gas cleaning, because a small contamination in the synthesis gas may ruin the FT reactor. This is not that crucial for a gas- turbine, but contaminations like tars have to be removed also prior to a gas turbine. Some gasification facilities will therefore be presented here, giving useful insight to the gasification process. There are three companies delivering gasification technology in Norway [55]:

! Organic Power AS Manufacturer of downdraft gasifiers with maximal power at 2 MW, aimed at waste treatment

! Enviroarc Technologies AS Manufacturer of updraft slagging gasifiers integrated with a plasma reactor with capacities down to 1 t/h. Aimed at waste treatment.

! Prototech AS Manufacturing fuel cell systems, but also interested in integrated systems of biomass gasification.

Biomass-fuelled combustion plants normally have net electric efficiencies (based on lower heating value) between 25 and 30%. The main reason for this low efficiency is the relatively small size of plants (in particular, the steam turbine) built as a result of limitations on fuel availability and/or the logistics of fuel supply. Employing a gasifier in a power cycle opens the way to increase the process-energy efficiency substantially by utilising the energy-rich gas in a gas turbine or gas engine [57].

57 Wood has a higher hydrogen/carbon ratio, and oxygen/carbon ratio than fossil fuels. This results in a higher gasification yield of both gases and hydrocarbons such as tars. The amount and composition of the tars is dependent on the fuel, pyrolysis conditions and secondary gas phase reactions. These tars are not a problem if they do not polymerise or condense. However, if the tar is allowed to condense when the gas is cooled down, considerable problems with equipment contamination (such as filter clogging) and waste water cleaning can result [57].

However, to realise this potential, removal of tars, particulates, acids and nitrogen compounds from the gas is a prerequisite to meet process and emission standards. In addition to the need to clean the gas, both gas turbines and engines require a minimum heating value of the gas. Since alkali compounds are also detrimental to modern gas turbines, causing corrosion and deposits at the high working temperatures of modern gas turbines, they also have to be removed from the fuel gas [57].

Figure 30: General process scheme for power production through gasification [57].

Some pilot plants are presented here; two more are in appendix II.

6.2.1 Güssing – gasification, FT In the south-eastern parts of Austria is there a small community that are based upon 100 % renewable energy resources, mainly biomass. An important part of this energy system is the pilot plant in Güssing, where biomass is gasified and then burned in a gas engine. The excess heat is distributed through the district heating system. The references are: the webpage of RENET [48], OPET Network (EC) [49] and Fürnsinn (2005) [19].

Technology

The pilot plant is an 8 MWth CHP plant. Biomass is gasified in a duel fluidised-bed (steam blown) reactor and the resulting gas is used to produce heat and power. Some basic information on this plant is as follows:

Start up of gasifier November 2001 Start up of gas engine April 2002 Fuel wood chips Fuel Power 8000 kW Electrical output 2000 kW Thermal output 4500 kW Electrical efficiency 25 % Thermal efficincy 56,3 % Total efficincy 81,3 %

The fluidised bed gasifier consists of two zones, a gasification zone and a combustion zone. The gasification zone is a bubbling bed fluidised with steam, to make a nitrogen-free producer gas. The combustion zone is a circulating bed fluidised with air which delivers the heat for the gasification process via the circulating bed material.

The producer gas is cooled and cleaned by a two stage cleaning system. A heat exchanger reduces the temperature from 850°C to about 150°. The first stage of the cleaning system is a fabric filter to remove particulates. In the second stage the gas is scrubbed to remove tar compounds. The dust from the filter, the spent scrubber liquid saturated with tar, and the condensate are thermally decomposed by recycling them to the combustion zone of the gasifier. The clean gas is finally fed into a gas engine to produce electricity and heat.

Figure 31: The Güssing process diagram [48]

From November 2001 to the end of July 2004, the gasifier has been operated for about 12,000 hours and the gasifier in combination with the gas engine for nearly 9000 hours.

The main characteristics of the producer gas include a low nitrogen content and high hydrogen content (H2 to CO ratio of 1.6 – 1.8). This high H2 to CO ratio implies a well suited synthesis gas for Fischer-Tropsch (FT) conversion to diesel fuels. A slip-stream of about 10 Nm³/h of product gas is sent into gas cleaning and downstream FT reactor. The production of FT diesel is done in cooperation with the “University of Technology, Vienna”, where extensive research is performed.

6.2.2 Värnamo An integrated gasification combined cycle (IGCC) was built in 1991, at Värnamo, Sweden. The plant was the first of its kind, utilising wood and with a complete IGCC cycle. The plant is now part of the CHRISGAS Project, which is funded by the EC 6th Framework Programme and the Swedish Energy Agency. The aim of the CHRISGAS Project is to demonstrate, within a five-year period, the production of a clean hydrogen-rich synthesis gas from biomass. The references are: Chrisgas’ webpage [53] and Ståhl (1998) [54].

Technology The dried and crushed wood fuel is pressurised in a lock hopper system and is fed by screw feeders into the circulating fluidised bed (CFB) gasifier. The fluidisation medium of the gasifier is air, the operating temperature is 950 - 1 000°C and the pressure is approximately 18 bar. Most of the tars are thermally cracked at this temperature. About 10% of the air is extracted from the gas turbine compressor, compressed further in a booster compressor, and then injected into the bottom of the gasifier.

After the gasifier, the gas produced flows to a gas cooler and a hot gas filter. The gas cooler cools the gas to a temperature of 350 - 400°C. After cooling, the gas enters the candle filter vessel where particulate cleanup occurs. The gas generated is burned in the combustion chambers and expands through the gas turbine, generating 4.2 MW of electricity.

The hot flue gas from the gas turbine is ducted to the heat recovery steam generator, where the steam generated, along with steam from the gas cooler, is superheated and then supplied to a steam turbine (40 bar, 455°C), generating 1.8 MWe. The process scheme is shown below:

Figure 32: Process scheme for the Värnamo pilot plant [53]

The pilot plant was temporally shut down in 2000, after 8500 hours of gasification and 3650 hours of integrated IGCC operation. The requirements of the Chrisgas project implied changes to the moth-balled pilot plant. It is far cheaper to adjust the existing pilot plant than building a new one.

The gasification plant after rebuild will have these up-grades: ! Pressurised oxygen/steam blown gasification ! Hot gas cleaning ! Reforming and upgrading of product gas

The quantitative targets are: ! To achieve a gas generation capacity of 3500 Nm3/h of wet gas ! To accumulate 2 000 hours experience of pilot plant operation

The Värnamo pilot plant will be one of the first with hot gas cleaning, enabling more effective utilisation of the producer gas, as heat may be retained in the gas on the way to the combustion chamber.

6.2.3 Choren, Fischer-Tropsch production at a pilot plant in Freiberg Choren has developed a process for production of diesel through a synthesis gas production process with subsequent Fischer-Tropsch reactor. After conducting extensive tests between

1998 and 2001 in a 1 MWth pilot plant, Choren reported that the process produces a tar-free gas without the use of any catalysts. Other Choren milestone accomplishments include 12,000

61 hours of operation and successful integration of the gasifier with gas engines. By using oxygen as the oxidant the process should be able to produce synthesis gas suitable for conversion to liquid fuels [51]. The references are the Choren website [61], email from Choren [74], and Rudloff 2005 [62].

Technology Choren uses an entrained-flow gasifier, which they claims has the advantages of elimination of hydrocarbons and methane to a convincing degree and in addition providing the simplest and most elegant scale-up option for units with an output of up to 1,000 MW. This is in contrast to the review done by Bridgwater (2003) [7], where the entrained flow gasifier is classified with weak technology and low market attractiveness. This might be explained by the special needs of pure syngas for FT production, and the focus on power generation in the review of Bridgewater. The low market attractiveness shown in figure 13, is due to the need of small particle size feeding. This is solved by Choren by the pre-gasification, which may be seen as a pre-treatment. This pre-treatment is more expensive than conventional pre-treatment for power production, but as the FT products has a higher value and require a produces gas almost without impurities, this solution might be optimal.

Entrained-flow gasifiers are only suitable for the use of gaseous, liquid or dusty materials. If solid biomass is to be used, combined processes are required, where the solid biomass is turned into a gaseous, dusty or liquid substance in the initial stage. This is shown as the low temperature gasifier in figure 33.

In the Carbo-V® process, process heat is first used to dry the biomass to ensure that it only contains 15 – 20 % water. The biomass is then broken down into biocoke (a type of charcoal) and a low-temperature carbonization gas containing tar during the NTV (a low temperature gasification) stage. This involves partial combustion (carbonization) using gasification agent at temperature between 400 °C and 500 °C. This process produces two intermediate products: The low temperature gas, containing tars and the dusty biocoke (charcoal). These are separated and inserted into the gasifier at two different locations. The low-temperature carbonization gas is then fed into the combustion chamber and is partially oxidized using oxygen as the gasification agent. The heat, which is released as a result of the oxidation process, warms up the carbonization gas to temperatures that exceed the ash melting point of the fuels that have been used, i.e. 1300 °C – 1500 °C. At these temperatures any unwanted longer-chain hydrocarbons, e.g. tar and even methane, are broken down. The gas that is produced primarily consists of carbon monoxide, hydrogen, carbon dioxide and steam.

Figure 33: The process scheme of the Choren Carbo-V® process

The biocoke is discharged from the NTV process, cooled, ground down to pulverized fuel and is then blown into the stream of hot gas coming from the combustion chamber. A huge amount of heat is absorbed when gasifying the biocoke and this allows lowering the temperature of the gas to 800 °C – 900 °C in a matter of seconds. This “chemical quenching” process produces a tar-free gas with a low methane content and with high proportions of combustible carbon monoxide and hydrogen. This hot raw gas is then cooled, and dust particles and any unwanted substances (e.g. chlorides, sulfides, etc.) are removed using a multi-stage gas scrubbing process. The gas is then transmitted to the synthesis unit, where the FT process takes place at 200 C and 20 bar, with help of a cobalt catalyst. The solids in the raw gas, i.e. residual coke and fuel ash, which have been separated during the dry dust removal stage, are fed back into the hot combustion chamber pneumatically. The ash elements melt and flow down the inside wall of the combustion chamber into a water bath at the foot of the reactor. The vitrified, solid ash can then be used as a slag granulate, e.g. for road building purposes.

Feedstock Choren states that: “In principle; all feedstock that contains carbon and has average moisture content below 40 % can be gasified. For a specific project, the proposed mixture based on a feedstock analysis has to be evaluated” [74].

Efficiency At the $-plant, which is currently being built at Freiberg to manufacture SunDiesel, an overall degree of efficiency of 45 – 55 % is achieved with regard to the manufacture of the liquid

63 product (diesel), depending on which operating method is used. If biomass is used as the exclusive source of energy and if the electrical energy requirements for the auxiliary units and the air separation from the residual gas and waste heat are covered by the process itself (basic self-sufficient scenario), the degree of efficiency is lower than if the yield of diesel fuel is maximized, in which case 6.6% of the total input energy must be obtained as electrical energy from outside sources (partially self-sufficient scenario).

The first industrial BTL production plant in the world (($-plant) is currently being constructed and has the following parameters: ! Biomass flow rate: 10.5 t/h, equal to about 50 MW feed ! Biomass supplies: 5 days, “just in time” deliveries o dried wood chips o air-dried wood chips o waste wood o straw-like biomass (0 – 30 % share) ! Preparation using in-house drying facilities ! Oxygen gasification with system pressure at 4 bar with Carbo-V® FT synthesis at 30 bar ! Production of 1.8 t/h ( 13,000 t/a) of synthetic automotive fuel (diesel fuel)

Choren is seeking to construct several production units, each with a production capacity of 200,000 t of diesel every year. The first plant is expected to produce diesel in Lubmin near Greifswald from 2009 onwards. The requirements for a suitable location are:

! Adequate local supply of biomass ! Good transport infrastructure (railway, roads, shipping) ! Integrated network with existing chemical plant/refineries ! Area to disposal > 10 ha a

A commercial plant has to have a minimum size of 300 MW feed, referring to a fuel output of 100 000 ton/a [74]

Conclusion Choren is one of few who have managed to produce FT diesel based on biomass outside the laboratory. They offer commercial plants, but keep a low profile with regard to detailed technology description and results. The FT research done world wide communicated through journals and reports go on without the results from Choren. If (when) a commercial plant is build by Choren, they have to stand the severe market test. Because of limited access to experiment results etc. it is hard to evaluate the technology, but the claimed conversion efficiency is among the highest reported in the whole literature.

64 7 Energy Chain efficiencies Many of the conversions routes of biomass into biofuels require different energy inputs in order to obtain the wanted products. This involves all types of inputs as biomass transport, pre-treatment, compressors, heating, gas cleaning etc. A Well-to-wheel (WTW) analyse is the essential basis to asses the impact of future fuel and powertrain options [63]. A WTW analyse includes energy expended and the associated GHG emitted in the steps required to deliver the finished fuel and convert it into physical transport, which is the energy service that is sought. A renewable fuel affected with a considerable energy consumption in processing, might be less energy efficient than a fossil fuel. The WTW analysis is therefore of key interest.

A WTW analysis of biomass energy routes is very sensitive for the chosen assumption. The use and valuation of the co-products are of greatest importance.

The calculation of the greenhouse gas (GHG) emissions follows the factors given by IPCC. The factors are reflecting the intensity of the GHG effect for each gas. They are as follows [64]:

Greenhouse gas t CO2eq./ t

CO2 1

Methane CH4 23

Nitrous oxide N2O 296 Table 9: Greenhouse gas equivalence coefficients

The CO2-eq. emissions for each technology is adopted from [64],[65] and are subject to change because of different land use, types of fertilizer used and other parameters influencing the emissions of CO2, N2O and CH4. Especially the emission of N2O is subject to change because of different assumptions regarding alternative land use, fertilizer etc. Detailed specifications of assumptions are given by LBST [68] and EUCAR [64].

7.1 Hydrolysis – Fermentation – Distillation - Ethanol The EUCAR WTW report has an energy chain with ethanol production based on farmed wood. The process is based on a dilute acid (sulphuric) hydrolysis, followed by SSCF (Simultaneous Saccharification and Co-Fermentation). After some days of fermentation, the “beer” is sent for distillation. Lignin and flare gas from the waste treatment are used to produce electricity. This process is based upon the NREL process, and has an electricity surplus that is credited with wood (as for wood fired in a conventional steam turbine), as for the FT-plant. This leads to a WTT efficiency of 34 %. Conventional fossil gasoline fuel has a WTT efficiency of 87,7 % [66]. The details are found in the EUCAR report [65],[66]. The energy used to produce ethanol is shown below:

65 2 1.8 1.6 Ethanol road transport (150 km) and refuelling 1.4 1.2 Ethanol plant, 1 hydrolysis and SSCF 0.8 Road transport (50 km) 0.6 MJ-exMJ-fuel / 0.4 Wood farming 0.2 0 Ethanol from hydrolysis

Figure 34: Energy expended to produce 1 MJ ethanol. Data range: -0.09/+0.10 [65]

The ethanol producing process requires considerable amounts of energy as seen in figure 34. 1,94 times the energy in the fuel is used in farming, processing and transport.

The LBST report [67],[68] has also an energy chain with ethanol produced from lignocellulosic material. The sources are a) crop residue (e.g. straw), b) sugar beet pulp, and c) dedicated crop plantation (e.g. poplar). The latter fits best to the EUCAR report, and the assumptions are similar: 50 km biomass transport to the ethanol plant, where enzymatic hydrolysis take place. LBST bases their assumptions on the NREL process, as the EUCAR report. The WTT results are therefore similar, since also the transport distances are the same. All details are given elsewhere [67].

7.2 Gasification – Fermentation – Distillation - Ethanol There are not much available data on the fermentation of syngas. The report on syngas use and processes made by NREL in 2003 includes only one reference for efficiency of the fermentation process. The reported efficiency is 35 % [69]. The BRI Energy claims an efficiency of 45 %, and even higher when components like tyres, or other high carbon content materials are gasified. As a best estimate the middle value efficiency is used, giving a process efficiency of 40 %. Wood farming and transportation are assumed similar as for the FT diesel production. This gives the following energy use in production of ethanol:

66 2 1.8 1.6 Ethanol road transport 1.4 (150 km) and refuelling 1.2 Gasifier + Fermentation 1 0.8 Road transport (50 km) 0.6 MJ-ex / MJ-fuelMJ-ex / 0.4 0.2 Wood farming 0 Ethanol (BRI Energy)

Figure 35: Energy expended to produce 1 MJ ethanol [40],[65],[69]. Data range not available, but the data concerning the gasifier and fermentation is weak.

The efficiency values of the BRI process are highly insecure, and can not be compared directly with the efficiencies of hydrolysis or FT diesel production which are documented in several reports and journals.

7.3 Gasification – FT synthesis – Diesel/gasoline The EUCAR (2003) WTW report makes a triangular probability distribution between Choren [61], and Tjimensen (2002) [33], where the latter represents a growth probability of 0.8 as lower limit and 0.85 as best case. The process produces a surplus of electricity which is credited as wood [65]. The Choren process claims an efficiency of 51 % (pure diesel, meaning a recycling back to gasifier of low value products). The best estimation value is then chosen to be 48 % by EUCAR. The details are found elsewhere [65]. With further assumptions applied: Farmed wood collection, then road transport for 50 km to the FT 200 MW plant and another 150 km fuel transport by truck. The report states a Well To Tank (WTT) efficiency of 45.5 %. Conventional fossil diesel fuel has a WTT efficiency of 86.2 % [66]

67 2 1.8 1.6 Diesel dist. (150 km) 1.4 and dispensing 1.2 Gasifier + FT reactor 1 0.8 Transport (road 50 0.6 km) MJ-ex / MJ-fuel 0.4 Wood farming and 0.2 chipping 0 FT diesel

Figure 36: Energy expended to produce 1 MJ FT diesel (-0.10/+0.11) [65]

It is clear from figure 36, that the major losses lie in the gasifier and the FT reactor, but the conversion efficiency is considerably more efficient than the ethanol production shown in figure 35 and figure 34.

The total efficiency in the WTW analysis made by LBST [67], from biomass to diesel tank is 44.8 %. The assumptions applied are: Wood residues are collected and transported 50 km on road to the Fischer Tropsch plant 10 MW, where diesel is produced and then transported another 150 km by truck. The small difference between LBST and EUCAR is probably the smaller gasifier in the LBST report (10 MW).

7.4 Comparison of energy conversion efficiency from well to tank and resulting GHG emissions The different fuel chains are compared with conventional diesel and gasoline. A gas-to-liquid (GTL) chain is also represented to show the relative efficiency of the biomass chains compared to another “energy state shifting process”. The conventional diesel and gasoline chains consist of only transport and refining, there is no energy conversion. The chain efficiency is adopted from EUCAR [66].

68 0) Diesel, GTL plant, Pipe 4000 km NG

6) Ethanol, syngas fermentation, Farm.w ood

7) Ethanol, hydrolyse, Farmed Wood

8) FT Diesel, Farmed Wood

9) FT Diesel, Waste w ood

Primary energy (PE) provision

10) Conventional Diesel PE transport

Conversion/refining

11) Conventional Gasoline Final energy distribution

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 MJ-ex / MJ-endenergy

Figure 37: Energy used in biofuel production compared to conventional fuels and GTL

There are several interesting findings in figure 37. ! The difference in energy use of farmed wood or waste wood is marginal, as shown in chain 8 and 9. The longer transport of waste wood (sea 800 km and road 50 km) is compensated by less energy used in waste collecting and chipping. ! All alternative fuels have significant higher energy intensity in production than conventional fuels. FT diesel is the most energy effective of the biomass based fuels but requires 8 times more energy input than conventional fuels from well to tank (WTT). ! The production of FT diesel from biomass is slightly less effective than the GTL chain, emphasizing the high efficiency of the conventional fuels compared to any chain with conversion of energy condition (gas to liquid, biomass to liquid etc.). ! Hydrolyse of lignocellulosic material has the lowest efficiency. The same amount of wood feed into a gasifier with downstream FT reactor can deliver 34 % more energy as fuel.

The conversion of biomass into biofuel seems inefficient compared to the refining of crude oil into conventional fuels, but the chains are not directly comparable as conventional fuel is

69 fossil and a result of refining and the biofuel is converted from another energy form. The conversion of energy form requires normally considerably energy amounts. The production of electricity by coal, gas or biomass is not without losses. The energy conversion efficiency of biofuels is not poor compared to other conversion technologies. This is shown in figure 38, where common energy conversion routes are shown. Also electricity produced from biomass is shown in chain 3, 4 and 5. The chain efficiency is adopted from EUCAR [66].

1) El.prod Coal, state of the art

2) El.prod, CCGT, Pipe 4000 km, NG

3) El.prod, Farmed Wood, boiler

4) El.prod, Farmed Wood 200 MW gasifier

5) El.prod, Farmed Wood 10 MW gasifier

8) FT Diesel, Farmed Wood MJ-ex / MJ-endenergy

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 Primary energy (PE) provision PE transport Conversion/Power plant Final energy distribution

Figure 38: Energy conversion efficiency of some common energy chains

The comparison is done on an energy level as the electricity is considered as wanted product, as automotive fuel is the requested energy service from biomass. The comparison has major weaknesses because the use of electricity differs from the use of fuel. The purpose is to indicate the biomass conversion efficiencies related to other common energy conversion routes.

There are several interesting findings in figure 38. ! The efficiency of production of biomass derived fuels is comparable with conventional electricity production from coal or natural gas. The conversion of

70 biomass to fuels is not ineffective compared to other common conversion technologies as e.g. a coal power plant or compared to a CCGT. ! The energy required to collect and transport biomass or to conduct wood farming is not a major part of the total WTT energy use, and contributes from 6.2 % to 8.4 % of the total energy losses. ! Electricity production: A 200 MW gasifier (4) is more effective than state of the art coal power plant (1), and nearly as effective as the CCGT (2). ! The utilisation of biomass to electricity is more effective than coal to electricity, and almost as effective as natural gas (NG) to electricity. ! Electricity production: The gasification of biomass technology is fare more effective than conventional boiler, and “efficiency of scale” is crucial as shown by chain 4 and 5.

The resulting GHG emissions are of great interest as reducing these are one of the main reasons behind introducing more biomass derived fuels and power. The energy efficiency from figure 37 and 38 is shown on the x-axis, and the resulting CO2-eq. is shown along the y- axis in figure 39. The CO2-eq. emissions are adopted from EUCAR [65].

300 11) Conventional Gasoline

10) Conventional Diesel 250

9) FT Diesel, Waste wood

200 8) FT Diesel, Farmed Wood

7) Ethanol, hydrolyse, Farmed Wood 150 5) El.prod, Farmed Wood 10 MW gasifier g g CO2-eq / MJ-endenergy 4) El.prod, Farmed Wood 200 100 MW gasifier

3) El.prod, Farmed Wood, boiler

50 2) El.prod, CCGT, Pipe 4000 km, NG

1) El.prod Coal, state of the art

0 0.0 0.5 1.0 1.5 2.0 2.5 0) Diesel, GTL plant, Pipe 4000 MJ-ex / MJ-endenergy km NG

Figure 39: Energy efficiency to electricity or fuel with resulting CO2-eq emissions.

The most interesting findings in figure 40 are summarised below: ! FT diesel and electricity produced via gasification (chain 4,8,9) are energy efficient

ways of reducing CO2 emissions.

71 ! A shift to biomass energy sources offers a significant GHG reduction potential but generally at the cost of reduced energy efficiency. An exception is the electricity production with large scale gasification, which is more effective than coal and almost as effective as natural gas burned in a CCGT. ! It is obvious that the widespread use of coal arise from high availability and low prices

rather than energy efficiency. The resulting CO2-eq. emissions are considerable. The

figure shows how important substitution of coal is for CO2-eq. avoidance. Isolated seen

as a CO2-eq. avoidance problem should each ton of biomass replace coal in electricity production rather than replacing conventional gasoline or diesel, since each MJ

avoided coal provided electricity corresponds to 267 g CO2-eq. avoidance compared to

85.4 g CO2-eq. avoidance for 1 MJ avoided conventional diesel. The conversion is equally effective (chain 8 and 4) with a 200 MW gasifier.

! The production of GTL (FT diesel from NG) does not have nor energy or CO2-eq. avoidance advantages compared to conventional diesel. ! For the Norwegian case the coal substitution is relevant as the Nordpool electricity market and the HVDC cables connecting the Danish grid to the Norwegian grid, enables coal power to supply Norwegian electricity demand. ! The substituting of natural gas with biomass to electricity generation is highly relevant as CCGT is build at Kårstø (Norway) in 2005.

Energy chain details ! 10,11) The crude oil is shipped after production and conditioning, then refined and transported 150 km mostly on road. The crude oil pathways represent a basket of crude oils available to Europe. ! 0) The GTL plant is located 150 km from market and is state of the art, with an efficiency of 63 % including LPG and naphta. 75 % of product yield is diesel. The natural gas is transported through pipelines for 4000 km. ! 1) The coal power plant is conventional state of the art with an efficiency of 43,5 %. The coal is extracted in the area of the power plant, and the electricity is fed into the high voltage grid. ! 8,9) The FT plant has a gasifier at 200 MW, and excess electricity production is returned into the process through wood credits. Farmed biomass is harvested and transported for 50 km on road. The waste wood is collected, transported 50 km on road and then 800 km by ship. The final fuel is transported 150 km on road. ! 2) The natural gas to electricity transports gas in pipeline for 4000 km into a CCGT with an efficiency of 55 %. The power is delivered to the high voltage grid with minimal losses. ! 3,4,6,7) The biomass is considered with 0 % moisture for wood, but drying is taken into account when calculating transport and process. The wood farmed is poplar or willow, and grows at a rate of about 8 ton/ha. ! 7) The hydrolysis uses SSCF, and represents the best equipment demonstrated by 1999. The process is made electricity neutral, by giving wood credits for excess electricity. ! The efficiency of gasification and downstream fermentation of syngas is set to 40 %, but is highly insecure, since there is very little data available.

7.4.1 WTT Conclusion

The results show that considerable CO2-eq. emission avoidance is possible in shifting from conventional fuels to biofuels, though at the cost of increased energy use in production. The

72 ineffective production of biofuel is moderate compared to other common energy conversion routes. The FT diesel production is the most effective biomass based biofuel, and is almost as effective as natural gas to diesel (GTL), but with 7 % of the CO2-eq. emissions. Looking at alternatives to conventional fuels, one should consider biomass to decrease CO2-eq. emissions but also due to competing energy efficiency, in fuel production as well as in electricity production.

7.5 WTW energy efficiencies and CO2-eq. emissions When the whole WTW energy chain is studied the differences between conventional fuels and biomass derived fuels are less apparent, since the low efficiency of the automotive engine efficiency (Tank To Wheel efficiency; TTW) is low and thereby decreasing the appearance of the efficiency differences in WTT. The 2010 vehicles have an efficiency of 19.4 % for gasoline (PISI) and 25.5 % for diesel engine (DICI with exhaust filter).

The WTW chain indicates all required energy and CO2-eq. emissions from harvesting/extraction/processing, transport and conditioning/upgrading. Also the energy and

CO2-eq. emissions from combustion and transmission in the vehicle are considered.

The WTW energy and CO2-eq. emissions from some fuel chains in figure 39 points out the considerable difference between different energy routes. When there are comparisons between a chain and reference, the reference is the middle value of conventional diesel and gasoline.

180 1) DICI Conventional Diesel

160 2) PISI Conventional Gasoline 2b) PISI hybrid Conventional Gasoline 140 3) PISI, 5%Ethanol, hydrolyse, FW 120 4) PISI, 100% Ethanol, hydrolyse, FW 100 5) PISI, 100%Ethanol, fermentation, 80 Sugar beet 6) DICI FT Dieselmix, FW 60 7) DICI 100% FT Diesel, FW

WTW GFG WTW (gCO2-eq./km) 40 8) DICI FAME Dieselmix, oil-seed rape 20 10) FC hybrid, on-site reform, Pipe WTW energy (MJ/ 100 km) 4000 km, NG 0 11) FC hybrid, pipe, central 0 100 200 300 400 500 600 gasification, FW

Figure 40: WTW energy efficiency and WTW GHG emissions per 100 km

73 Figure 41 shows some chains available today, and some chains that are future options, as hydrogen fuelled vehicles. These chains are analysed in the next subsection. First some major findings concerning biofuels in 2010 from figure 41:

! The introduction of a hybrid engine offers energy use and CO2-eq. emission advantages as seen in chain 2 compared to chain 2b.

! Diesel engines are slightly more effective and thus offers reduced CO2-eq. emissions per driven km, comparing chain 1 with 2.

! The use of FT-diesel blends or ethanol blends reduces CO2-eq. emissions linear to blend ratio. For diesel: 0 % corresponds to chain 1. A 5 % blend corresponds to chain 5, and 100 % FT diesel is seen as chain 7. A straight line could be drawn between the chains. For ethanol: 0 % corresponds to chain 2, a 5 % blend to chain 3, and 100 % ethanol corresponds to chain 4. Also here a straight line could be drawn between the

different blends. Reduced CO2-eq. emissions are achieved with increased energy intensity as cost. ! The hydrolysis of wood is less effective than FT diesel, as shown in figure 37, and this

contributes to more CO2-eq. emissions from ethanol production, but also the processing

of ethanol bring significant more CO2-eq. emissions per MJ fuel than FT diesel processing. The need of propylene (from crude oil) steam (from natural gas) and the

use of NH3 (produced from natural gas) increase the CO2-eq. emissions from ethanol production.

! The use of FAME (Fatty Acid Methyl Ether) based on oil seed rape shows poor CO2-

eq. emission avoidance, due to high energy use in cultivation and high use of N-

fertilizer. The agriculture land used for rape oil seeds also contributes to CO2-eq. emissions. Rape seed is mainly a low-input break crop, to rest the soil between other more profitable cereal crops. The use of oil-seed rape as feedstock to FAME biodiesel is the most common production route [76]. The results shows that FAME biosdiesel

derived from rape seed dos not have the low CO2-eq. emissions as FT diesel, and

should be not be confused with each other as CO2-eq. emission characteristics differ considerably. ! The main production of ethanol today is done in Brazil and USA, based on sugar cane and corn respectively. The shown chain 5 represents the production possible in Europe from sugar beet. The colder climate in Europe, hinder the production of ethanol from

sugar cane, which is much more effective, and thus has great CO2-eq. emission

avoidance potential. The chain 5 shows poor energy efficiency and also low CO2-eq. emission avoidance. This is mainly due to cultivation (N-fertililzer) and the ethanol process plant, which need energy for drying, distillation and ethanol purification, which is supplied by natural gas in these chains.

Some major findings concerning future transportations fuels (2020+) and WTW chains shown in figure 41: ! Use of de-centralised reforming of natural gas to hydrogen, and fuelled in a 2010 fuel

cell with hybrid engine (chain 10) gives advantages in CO2-eq. emissions (- 42 % from

74 reference) and has also minor energy efficiency advantages compared to reference. Reforming of hydrogen is likely to be the most common production route of hydrogen in the first period with hydrogen as transportation fuel, since this is known technology and rather cheap compared to electrolysis. ! A production of hydrogen from biomass in a central gasifier (200 MW), and subsequent pipe transport of hydrogen to a filling station gives high WTW energy

efficiency (same as hydrogen from natural gas) and at the same time low CO2-eq.

emissions (chain 11). The WTW CO2-eq. emissions are at same level as 100 % FT diesel, but the WTW energy efficiency is 2.4 times better. ! The biomass to hydrogen (chain 11) is as WTW energy efficient as natural gas to

hydrogen (chain 10), but the CO2-eq. emissions are reduced with almost 90 %. Both chains are more energy efficient than hybrid engine fuelled with conventional gasoline from crude oil.

General assumptions etc.: ! The PISI (Port Injection Spark Ignition) engine is adopted from EUCAR and uses 6.26 litre/100 km, a ethanol blend (E5) uses 6,36 litre/100 km, and represents a typically compact 5-seater European sedan [66]. The same car with diesel engine, the DICI (Direct Injection Compression Ignition) uses 5.0 litre/100 km. The specifications represent 2010 vehicles [66]. ! The driving pattern follows a mix of urban and longer distance driving, details in EUCAR [63]. Chain assumptions: ! The fuels are produced as described in the WTT analysis, chapter 6.4 and further combined with engines and automotives as described as general assumption. Exception for chain 5,8,10 and 11 which is not a part of chapter 6.4. They are included to give more perspective on future options and their qualities. ! Chain 8; the residues from FAME production are used as animal feed; this is quite common as the price obtained is high compared to alternative use, though the energy efficiency is poor. ! Chain 10; natural gas is transported 4000 km in pipe and reformed at decentralised plants. The engine used is a hybrid fuel cell ! Chain 11; woody biomass is farmed and gasified in a central gasifier (200 MW), the hydrogen is transported in pipe to filling station. The engine used is a hybrid fuel cell.

7.5.1 WTW conclusion FT diesel is highly competitive with other alternative fuels to conventional fuels, and offers the highest efficiency and CO2-eq. emission avoidance potential (- 88 %) of biomass based conversion technologies available today. The use of hydrogen produced from natural gas offers high efficiency, but only a CO2-eq. emission reduction of 42 %. The gasification of biomass to hydrogen and fuelled in the same hybrid fuel cell offers the same efficiency, but a

CO2-eq. emission reduction of 93 %. The production of FT diesel today is a moderate energy efficient, but highly CO2-eq. emission reducing technology. The shift towards hydrogen production from biomass offers one of the highest WTW energy efficiency and almost zero

CO2-eq. emissions.

75 8 Case study: Trysil Trysil is located in southeast Norway, in the region of Hedmark. The area is known for forestry, and is the main area for the Norwegian forest industry

Trysil

Chopped for sale, m3 2003

Figure 41: The chopped volume in 2003 and the location of Trysil

The Norwegian transport demand has increased significantly the last 60 years. In 1946 was average transport 4 km per day, with 1.8 km by railroad. Today this has risen to 38.5 km per day with still railroad at about 1.95 km per day, meaning a considerably increase in use of passenger cars (29 km per day, up 13 times since 1946) and airplane [72]. The use of automotive fuels in Trysil the last decade is shown in figure 41, where the fuels used in mobile combustion are shown.

76 400

350

300

250

200

TJ/year 150

100 Gasoline Diesel 50

0 1991 1995 2001

Figure 42: Use of gasoline and diesel in mobile combustion in Trysil [73]

The figure shows a steady consumption of gasoline and an increase in diesel consumption. For the case study of Trysil in 2010, the gasoline consumption is assumed to be constant at 170 TJ/year, equal to 3935 ton of gasoline, or 5 282 000 litre. The diesel consumption is assumed to follow the same development from 2001 to 2010 as for 1991 to 2001, thus landing at 227 TJ/year in 2010 equal to 5267 ton, or 6 330 000 litre of diesel annually.

450 400 Gasoline Diesel 350 300

250 200 TJ/year 150 100 Assumed consumption 50 0 1991 2001 2010

Figure 43: Assumed development of gasoline and diesel use in Trysil

The diesel consumption might be replaced by 100 % FT-diesel. A substitution of the 6 330 000 annually litre of diesel in 2010, requires an amount of approximately 11 600 ton of annually biomass feed to the gasifier, or a power input of 1.45 ton/h equal to 4.8 MW (with 8000 hour of operation annually). This size would probably not be economically as e.g. Choren claims that a commercial plant should be at minimum 300 MW. The energy chains done by EUCAR and LBST assume in theirs “best estimates” a gasifier of 200 MW. It is therefore necessary with a production plant of this size to obtain the economy of scale advantages offered by a larger gasifier. 210 km from Trysil is the fuel market of Oslo and Akershus, which had a turnover of 304 million litre of diesel, and a 470 million litre of gasoline sold in 2004 [77]. A pilot plant could be interesting to cover local diesel or petrol

77 demand. A commercial plant is dependent on access to a larger market. The question is then how to gather the biomass to an economic price and weather enough is available in the region. This is discussed in the next part.

8.1 Biomass resources The plant location in Trysil has the advantage of considerable amounts of biomass as local forest, but lack the opportunity of a seaport with possible receipt of large amounts of biomass. The gasifier used in the energy chain modelling done by EUCAR has a size of 200 MW, and a feed of 336 kT of dry biomass each year. This is collected from an area of 0.6 Mha, where 50 % is assumed as arable land (green area in figure 44) and 10 % out of this arable land is farmed wood. The yield is assumed to be 10 dry t/ha annually. The Norwegian yield is stated to 0.1 m3/dekar [70] with favourable conditions. This yield corresponds to about 5 dry t/ha. The average transport length is therefore longer in Norway compared to the data used by EUCAR. The catchment area in the EUCAR study is shaped like the map illustrates in figure 45.

Figure 44: Catchment area (green) with an average transport distance of 50 km

The biomass potential in Trysil is investigated by IFE, and the study implies wood chips, pulp wood, sawdust, stub chips as well as wood shavings. The study is not suited to cover the demands of a commercial biofuel plant as the need of a 200 MW plant is considerable, and needs rethinking, as the infrastructure and ways of wood farming will alter from the available pulp demand of today with a higher focus at cost effective farming. The potential exceeding 200 GWh in figure 46 is based upon more general assumptions of 1 [NOK/(m3*km)] The wood is collected within an area of 100 km. To feed a 200 MW plant, 8000 hours a year, demands 1600 GWh, which is far more than the amount chopped in Trysil today. The total chopped volume in the whole Hedmark county is 4700 GWh [70], it is therefore clear that a commercial plant has to develop a new market for cheap biomass. The biomass market in Sweden is more developed and delivers large amounts of biomass to CHP plants and as feedstock to pellets production etc. Studies on the Swedish pellets market indicates a raw material cost of 7.7 €/MWh when the pellets plant produces 80 000 ton of pellets annually [80]. There are therefore reasons to assume a possible lower price as new techniques and practices occur pushing the price downwards to Swedish level. As biomass is expensive to transport there is no guarantee against regional price differences and strategic marked

78 behaviour pushing the price upwards. Long term biomass deliverance at an economic price is therefore a presumption. Trysil lies near the Swedish border, but the price of Swedish biomass delivered in Trysil is not investigated but should be found prior to further planning on biomass potential in Trysil.

15 € /MWh 10

0 0 400 800 1200 1600 2000 Potential [GWh]

Figure 45: Potential and cost of wood in Trysil within a range of 100 km [79]

The importance of biomass cost is evident from figure 47, where the sensitivity of the biomass is shown. The general plant assumptions are based on Tijmensen [33], where load factor is 8000 hours/year, investment of 1000 €/kW thermal, 10 % interest rate and 15 years lifetime. The FT diesel conversion efficiency is set to 40 %. The production cost of FT diesel consists of biomass cost, operational and maintenance costs (O&M) and investment costs.

35 Biomass 30 O&M 25 Capital cost

10 FT costdiesel [/GJ]€ 5

0 7 10 13 16 19 22 25 Biomass cost [€/MWh]

Figure 46: Sensitivity of biomass feedstock price

It is evident from figure 47 that feedstock price is of major importance. The decision to realise a commercial plant in Trysil is dependent on stable low-price biomass, to be competitive with conventional diesel.

79 The production of ethanol is also possible, but has the disadvantage of competing biomass derived ethanol delivered from Brazil. This biomass produced from sugar cane in Brazil might be delivered to a price lower than the production cost in Trysil. At the moment none of these are possible as ethanol has the same taxes as liquor. With respect of regional development and employment it is favourable with FT diesel production as FT diesel has no other competitor than conventional diesel. The production of ethanol might be feasible with import duty on foreign ethanol. Sweden imports most of their ethanol from Brazil, but is raising the import duty to enable better conditions for Swedish made ethanol. The case study for Trysil is considering the production of FT diesel, as it has several advantages compared to ethanol in Norwegian contest: ! Less insecurity of biodiesel import compared to ethanol import, which can be delivered from Brazil to a price much lower than the ethanol production costs in Norway. ! Higher energy yield and conversion efficiency for FT diesel compared to ethanol. ! A more proven technology with lignocellulosic feedstock with already one commercial market participant. ! Fewer technology choices to be made considering pre-treatment and process pathways. ! Easier to implement in the energy system as all blends and also pure FT diesel is suitable to diesel engines. The ethanol may only be used as low concentration blends with gasoline if no modification of engine is to be made.

8.2 Capital cost of a FT diesel plant The capital cost of an FT diesel plant can consists of the following components [33], but varies dependent on the different concepts. The aim of the figure is to give an impression of the breakdown of investment cost of a possible FT diesel plant.

Others; 4 %

Hydrocracking; Pre-treatment; 11 % 21 %

Gas turbine; 7 %

FT reactor; 6 %

Gasifier; 18 % CO/H2 shift; 10 %

Gas cleaning; Oxygen plant; 18 % 15 %

Figure 47: Breakdown of investment costs for a IGT once through concept at 367 MW [33]

80 The investment costs of a FT plant consist of several units, shown in figure 48. The concept uses a gas turbine to utilize the remaining synthesis gas after the FT reactor. The plant uses enriched air as oxidant and pressurized gasification to keep downstream equipment size low.

8.3 Scale importance The size of the plant is of major importance, as this example for FT diesel shows. The biomass feedstock is relative cheap at 2 €/GJ, corresponding to 60 NOK/MWh. Figure 49 shows the cost reduction as function of plant size. The biomass cost is held constant, where in practice biomass cost should increase due to higher logistic costs as the demand raises [33].

30 25

/ GJ FT liquid FT GJ €/ 10 5

0 100 200 300 400 500 600 700 800 Scale (MWth)

Figure 48: Effect of scale on the production costs [33]

Economy of scale has a major influence on the production costs as seen in figure 49. The costs decreases rapid to 300 MW installed thermal effect and then has a more gradual decrease. It is evident that small scale commercial FT plants are not economic feasible.

8.4 Efficiency importance The energy conversion efficiency from biomass to FT diesel is of importance, as less biomass is needed and capital cost decreases due to higher amounts of produced fuel. All parameters are held constant as given in [33] as the conversion efficiency is altered as shown in figure 50:

81 24

16 FT diesel [ € diesel /GJ] FT 14

12 30 % 34 % 38 % 42 % 46 % 50 % 54 % Efficiency

Figure 49: The sensitivity of conversion efficiency

The conversion efficiency is important for overall economic performance, but not as major as scale and biomass cost. It is a technological barrier, unlike the more logistical and economic barrier of biomass farming and economy of scale.

82 8.5 Barriers to introduction of biofuel plant in Trysil The barriers are of economical, technical, social and technical character. Not all are mentioned here, but the assumed major ones are commented and analysed.

Biomass deliverance A presumption is a long term supply of biomass to a price lower than 13 €/MWh, and in a quantity of 1600 GWh annually. This barrier could be overthrown by new techniques and practices. A problem may be the local forest owners and accompanying transaction costs. The quantum, expected price and demanded cost effectiveness is new to the forest industry. The Swedish market has deliverances to large scale pellets plants of 100 000 ton at 8 €/MWh, which indicates possible lower prices also in Trysil, although biomass markets are local in nature as the transport costs are high. It would therefore be an advantage with a sea port with access to more biomass markets. It is also of great importance with social accept in Trysil, as much more forest is to bee utilized compared to before. Local ownership and goodwill is therefore of great importance. This barrier is assumed possible to overthrown.

Market access

Public information about the CO2 avoidance and advantages of biofuels on national level is important to raise the acceptance. The FT diesel contains little or no contaminants (like sulphur and aromates) [33] and offers therefore significant better air quality in urban areas, where air quality often is a problem. The market introduction might be easier with focus on these supplementary benefits. Mentioned could also be the benefits of regional employment. If different types of waste are gasified and turned into fuels, additional communication advantages are achieved as slogans as “fuel your car with waste” gain attention in the public. If the production costs are low enough it might as well be blended with conventional fuels without notice, up to 100 % for FT diesel and up to 5 % for ethanol [2]. The blend issue and introduction of E85 or other blends introduce another barrier to ethanol as new engines and guarantees have to be introduced. The FT diesel on the other hand is adaptable in every diesel engine as blend or pure.

Technical barriers The stable operation of the plant is a presumption of a commercial biofuel plant. The production experiences of biofuels based on cellulosic materials are highly limited and are therefore a major challenge. This insecurity is seen as the major obstacle to commercial operation of biofuel plants. The expected gained experience in this field the coming years will probably considerably reduce the insecurity, and increase market attractiveness.

The investment cost of a biofuel plant has to be lowered through efficiency improvement and learning curves. This is crucial for further expansion. Operational experience will improve knowledge and know-how in the technique of producing biofuels at low cost, and how to

83 decrease investment cost through modifications and new concepts. As installed capacity by now is limited, the expected cost reduction through learning is considerable.

Economic barriers

The CO2 tax and mineral oil tax is a presumption of competitive fuels based upon biomass, and this taxes has to be kept or increased to secure long term perspective and predictability. The tax on ethanol as a liquor has to be removed, and it has be introduced import duties on foreign ethanol to enable a production of ethanol in Trysil or elsewhere in Norway.

The barriers of ethanol production and importance are indicated in figure 50:

Recommendation of attention: Barrier Low Middle High Biomass deliverance Economic framework Market access Operational experience Investment cost

Figure 50: Main areas of attention and barriers against ethanol production in Trysil

The pathways from wood to ethanol are varied and consist of many possible solutions. The pre-treatment technology and hydrolysis are examples. It is hard to predict the most cost effective solution, and different scientist group has different opinions, with accompanying altering priority. The FT diesel technology on the other hand is more uniform. Still altering gasification technologies compete, but the knowledge of gasification is old and well established. The FT reactor process is partly understood and predictable. The major challenge is stable operation and the gas cleaning step, which has to be able to sort out particles other than CO and H2.

The barriers of FT diesel production in Trysil are indicated in figure 51:

Recommendation of attention: Barrier Low Middle High Biomass deliverance Economic framework Market access Operational experience Investment cost

Figure 51: Main areas of attention and barriers against FT diesel production in Trysil

The economic framework is in place, as no taxes apply to FT diesel. Also market access is secured due to the 100 % compatibility with conventional diesel. To obtain tax exemption the

84 blend has to contain more than 50 % biofuel, which is crucial for the overall economy, as shown in chapter 9.

8.6 Conclusion to the case study of Trysil Introduction of commercial production of biofuel in Trysil raises some questions that have to be properly evaluated and answered. ! FT diesel is preferred in favour of ethanol as the FT diesel is produced more effectively, has fewer barriers and is easier to implement in today’s energy system. ! The location of Trysil is preferable of a pilot plant to cover local automotive fuel demand, but to enable a commercial operation, the access to a larger market is crucial. With a smaller pilot plant decreases the biomass feedstock barrier considerably, but clearly exclude a commercial operation without subsidies and economic support. ! The biomass deliverance to a commercial plant has to be secured to a price below 12- 14 €, and in the volume big enough to feed a 200 – 300 MW plant (1600 – 2400 GWh annually). The biomass cost is of major importance for the total production cost of FT diesel. ! A seaport is preferable as it enables access to different biomass markets and thereby increases the competition and avoids exertion of market power. A seaport is not available in Trysil and other ways to avoid exertion of market power has to be found. ! The economy of scale is crucial for the overall economy, and a plant size of minimum 200 MW thermal is recommended.

85 9 Production cost The production cost of FT diesel and ethanol based on biomass is dependent on many factors, as biomass resource cost, available feedstock, chosen technology, lifetime of production plant, reliability of technology, operation costs and economy of scale to mention some. Further is the economy dependent on the crude oil price, taxes on conventional fuels, available markets, and market instruments introduced by the government (tax exemption, blending requirements introduced by law, subsidies, etc.) to mention some external factors determining the economy of biofuel production.

The production cost has been analysed by several institutions, some are shown here. Details about assumptions are not given, as these are diverse and several, and not the aim of this study. The sources of the FT diesel are: NREL [69], Hamelinck [60], Tijmensen [33], KanEnergi [76] and IEA [4]. The ethanol costs are adopted from Lindstedt [38] and IEA [4]. The fermentation of syngas has very limited data, the only two reports are NREL [69] and BRI Energy [40], but the two are very close in conclusion. The costs ranges are shown in green and average cost as a red mark.

/GJ€ 10

0 FT diesel Ethanol (hydrolysis) Ethanol (BRI)

Figure 52: Production cost range of biofuels, middle value as red mark.

The Norwegian diesel price is in the range of 30 – 38 €/GJ (10 – 11 NOK/litre), and therefore well above cost range of FT diesel though this price includes mineral oil tax and CO2 tax. The petrol is sold for 38 – 46 €/GJ (10-12 NOK/litre) including the same taxes. The specific taxes for 01.01.2005 are shown in table 10 [78]:

Diesel taxes: NOK/litre €/GJ

CO2 tax: 0,78 2,72 Mineral oil tax: No sulphur 2,92 10,18 Mineral oil tax: Low sulphur 2,97 10,35

86 Petrol taxes: NOK/litre €/GJ

CO2 tax: 0,78 2,72 Mineral oil tax: No sulphur 4,03 15,51 Mineral oil tax: Low sulphur 4,07 15,70 Table 10: Norwegian taxes on conventional petrol and diesel

The costs of conventional fuels are therefore much higher than the production costs of biofuels thanks to the mineral oil tax and CO2 tax. This is shown in figure 53, where the production costs of conventional fuels [2] inclusive taxes are compared with biofuel production costs. The cost of ethanol from Brazil is also shown to emphasize the competition of ethanol production and the need of securing home markets by subsidies or import duty.

15 € /GJ

0 FT diesel Ethanol Ethanol (BRI) Production Production Ethanol (hydrolysis) cost of diesel cost of petrol delivered incl. taxes incl taxes from Brazil

Figure 53: Production cost of biofuels compared with production costs of conventional fuels including taxes

Figure 53 indicates the potential economy of a production of biofuels in Norway. The estimates are general positive as some studies operate with higher costs. The studies referred here are suited large scale commercial biofuel production.

The blends with less than 50 % biofuels will not be considered as tax exemption fuels. There is far better economy to produce E85 and pure FT diesel rather than lower concentration blends with the existing laws, assuming abolition of liquor tax on ethanol when used as automotive fuel. The tax exemption is crucial for the economy, as indicated in table 10.

87 10 Conclusion The production of biofuels from lignocellulosic material in Norway has many advantages.

Reduced CO2 emissions, increased employment in rural areas, increased energy security, higher national income from increased crude oil sales abroad, possible technology transfer to abroad, cleaner burning resulting in better air quality in urban areas and a new industry enabling a less oil dependent economy and energy system, are some of the reasons to introduce biofuels produced from wood. The fuels may be used in existing infrastructure and engines, thereby leap-frogging one of the major barriers to hydrogen and other future fuel alternatives. Looking at alternatives to conventional fuels, one should consider biomass to decrease CO2-eq. emissions but also due to competing energy efficiency, in fuel production as well as in electricity production.

The most promising technology available today is the production of FT diesel through gasification and downstream FT reactor. It offers high energy efficiency (about 50 %) and low CO2 emissions (reduction of about 85 %). The production of ethanol is less effective but ethanol has a very high octane number and is therefore used as a fuel additive to improve engine performance, typically added as E5 or E10. The use of higher concentrations blends of ethanol such as E85 is possible, but requires small changes to petrol engines.

The biofuels conversion technologies based on lignocellulosic material are insecure, and little experience from commercial operation is by know gathered, but the focus is increasing throughout Europe and north/south America. EU has a goal of 2 % by 2005 and 5.75 % by 2010. The Norwegian goals are 2 % in 2007 and 4 % in 2010, which indicates a raising focus the coming years.

Norway has a large unused forest, which risk decomposing, due to lowered timber prices the last decades followed by low utilisation of the forest. This potential may be used in biofuel production which is economic thanks to exempt from crude oil taxes as mineral oil and CO2 taxes. The taxes amount to 4.8 NOK/litre gasoline and 3.7 NOK/litre diesel, and can be enough to cover the production cost-difference between conventional fuel and biofuels.

Trysil is known for its forest industry, and has the raw materials needed to produce biofuel. FT diesel is of most interest due to more factors; its 100 % compatibility with today’s energy system, high conversion efficiency, no competitive ethanol import from e.g. Brazil and a more proven technology with at least one “commercial” manufacturer.

A commercial FT plant in Trysil has to overcome some barriers. One of the main areas of attention is external, as commercial operation experience is needed to reduce costs and enable economic predictability and risk management. Another main barrier is internal, and located to Trysil; the deliverance of cheap biomass in large amounts is a presumption of any commercial operation of a FT diesel plant. Thus a seaport is advantageous as it enables access to more

88 markets and avoids local exertion of market power. The effect of economy of scale on production cost is considerably and obstructs the building of a commercial FT plant with a size smaller than 200 MW thermal. The dependence of biomass cost is showed in figure 54, where the cost of conventional diesel production inclusive taxes is shown as a red dotted line.

35 Biomass 30 O&M 25 Capital cost

10 FTcost diesel [/GJ]€ 5

0 7 10 13 16 19 22 25 Biomass cost [€/MWh]

Figure 54: Sensitivity of biomass feedstock price

It is clear from figure 54 that the biomass costs are of great importance, and the question of biomass deliverance has to be answered prior to further planning on a commercial FT plant in Trysil. The biomass market in Trysil of today offers large amounts of biomass (200 MW) to 18 – 25 €/MWh, which is clearly not economic without subsidies or other economical support. The same amount of biomass in Sweden can be delivered for 8 €/MWh, which indicates possible lower costs. A location with seaport access would be preferable, but not necessary if large amounts of biomass can be delivered to low prices (< 13 €/MWh) by truck at long-term contracts.

89 11 References

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92 www.gastechnology.org/webroot/downloads/en/IEA/BiomassGasificationCountryRep ortsOct2004.pdf accessed 2005-10-27 [56] Spath P.L., et.al. Preliminary Screening —Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis on the Potential for Biomass- Derived Syngas, National Renewable Energy Laboratory (NREL) 2003 [57] Morris M., et.al., Update on Project Arbre, UK – A wood fuelled combined-cycle demonstration plant, TPS Termiska Processer AB [58] Pitcher K., The Arbre Project: Progress Achieved, Biomass and Bioenergy Vol: 15, 3/1998, 213-218 [59] Grønli Morten, Biobrensler, SINTEF Energiforskning AS, Bionett Temablad, Only available in Norwegian. [60] Hamelinck Carlo N., et.al., Production of FT transportation fuels from biomass; technical options, process analysis and optimisation, and development potential, Energy research Centre of the Netherlands (ECN), Utrecht University, ISBN: 90-393- 3342-4, 2003 [61] Choren website at www.choren.com/de/ accessed at 2005-11-02 [62] Rudloff Matthias, Biomass-to-Liquid Fuels (BtL) - Made by CHOREN Process, Environmental Impact and Latest Developments, Automobile & Environment at Belgrade EAEC Congress, May 2005 [63] EUCAR, Edwards R. et.al, Well to wheels analysis of future automotives fuels and powertrains in the European context, EUCAR, CONCAWE and Joint Research Centre of the EU Commission, Version 1b, 2004 [64] EUCAR, Edwards R. et.al, Well to wheels analysis of future automotives fuels and powertrains in the European context, well to tank report, EUCAR, CONCAWE and Joint Research Centre of the EU Commission, Version 1, 2003 [65] EUCAR, Edwards R. et.al, Well to wheels analysis of future automotives fuels and powertrains in the European context, well to tank report, EUCAR, CONCAWE and Joint Research Centre of the EU Commission, Appendix 1, 2003 [66] EUCAR, Edwards R. et.al, Well to wheels analysis of future automotives fuels and powertrains in the European context, well to tank report, EUCAR, CONCAWE and Joint Research Centre of the EU Commission, Appendix 2, 2003 [67] LBST, GM well-to-wheels analysis of energy use and greenhouse gas emissions of advanced fuel/vehicle systems- a European study; report for General Motors, BP, ExxonMobil, Shell and TotalFinaElf, Sept. 2002 www.lbst.de/gm-wtw [68] LBST, Annex “Full Background Report” –Methodology, Assumptions, Descriptions, Calculations, Results- to the GM well-to-wheels analysis of energy use and greenhouse gas emissions of advanced fuel/vehicle systems- a European study; report for General Motors, BP, ExxonMobil, Shell and TotalFinaElf, Sept. 2002 www.lbst.de/gm-wtw [69] NREL, Spath P.L., et.al., Preliminary Screening —Technical and Economic Assessment of Synthesis Gasto Fuels and Chemicals with Emphasis on the Potential for Biomass-Derived Syngas, National Renewable Energy Laboratory (NREL), December 2003 [70] Statistics Norway, Forestry statistics 2003, www.ssb.no/emner/10/04/20/nos_skogstat/nos_d320/nos_d320.pdf accessed 2005-11- 08 [71] Statistics Norway, Official webpage, theme page: forest, Only available in Norwegian: www.ssb.no/skog accessed 2005-11-08

93 [72] Statistics Norway, Official webpage, www.ssb.no/emner/00/norge/transport/14- transport.htm accessed at 2005-11-08 [73] Statistics Norway, Official webpage, Energitall for din kommune, www.ssb.no/vis/magasinet/miljo/art-2004-05-18-01.html accessed 2005-11-08 [74] Personal email from Choren, Matthias Rudloff 10.11.2005 [75] EUCAR, Edwards R. et.al, Well to wheels analysis of future automotives fuels and powertrains in the European context, well to wheels report,Version 1b, EUCAR, CONCAWE and Joint Research Centre of the EU Commission,WTW Appendix 1, 2004 [76] Bernhard, Peter et.al., 2005, Biodrivstoff – Potensial for ny næringsvirksomhet En kort presentasjon av markedsmuligheter og teknologier for produksjon av biodiesel og bioetanol basert på trevirke, Eksempel: Norske Skog Union, Skien, KanEnergi AS, Only available in Norwegian [78] SFT (Statens Forurensnings Tilsyn), Reduksjon av klimagassutslipp i Norge; Oppdatert tiltaksanalyse for 2010 og 2020, Versjon 2, september 2005, ISBN 82- 7655-269-2, only available in Norwegian. [77] Statistics Norway, Official webpage: Accessed 2005-11-23 http://statbank.ssb.no/statistikkbanken/Default_FR.asp?Maintable=PetroleumSalg4&P Language=0&nvl=true&PXSid=0&tilside=selectvarval/define.asp&direkte=1 [78] Aylward Gordon et.al. SI Chemical Data, 4th edition, Wiley ISBN: 0-471-34021-9 [79] J.C. Johansen et.al. IFE 2005 Grønn utvikling i Trysil - med fokus på bioenergi [80] Näslund Magnus et.al. Teknik och råvaror för ökad produktion av bränslepellets Juni 2003 [81] NVE, Nordland Berg, Lena et.al. Bioenergiressurser i Norge October 2003 [82] Zumdahl Steven S, Chemical Principles, Fourth edition, Houghton Mifflin Company, ISBN: 0-618-12078-5

94 Appendix I: Gasifier reactor types and characteristics

Adopted from: A.V. Bridgwater / Chemical Engineering Journal 91 (2003) 87–102 All biomass fuelled gasifiers: Feeding can give problems. Ash slagging and clinkering potential

Downdraft (Co-current)-fixed bed reactor Solid moves slowly down a vertical shaft and air is introduced and reacts at a throat that supports the gasifying biomass. Solid and product gas move downward in co- current mode. The technology is simple, reliable and proven for fuels that are relatively uniform in size and have a low content of fines (below 5 mm). A relatively clean gas is produced with low tar and usually with high carbon conversion. There is limited scale-up potential to about 500 kg/h feed rate. There is a maximum feed moisture content of around 35% wet basis Examples: Biomass Engineering [1], Rural Energy [2], BTG&KARA [3], Fluidyne [4], Johanssen [5] Updraft (counter-current)-fixed bed reactor Solid moves down a vertical shaft and contacts a counter-current upward moving product gas stream, The technology is simple, reliable and proven for fuels that are relatively uniform in size and have a low content of fines (below 5 mm). The product gas is very dirty with high levels of tars, although tar crackers have been developed. Scale up limited to around 4 dry t/h feed rate. There is high thermal efficiency and high carbon conversion. Intolerant of high proportion of fines in feed. The gas exit temperature is low. Good turn-down capability Examples: Wellman [6], Volund [7], Bioneer [8] Bubbling fluidized bed Good temperature control & high reaction rates. Higher particulates in the product gas and moderate tar levels in product gas. Good scale-up potential to 10–15 dry t/h with high specific capacity and easily started and stopped. Greater tolerance to particle size range. Good temperature control. Tar cracking catalyst can be added to bed. Limited turn-down capability There is some carbon loss with ash. Examples: EPI [9], Carbona [10], Dinamec [11] Circulating Fluidized Bed All the features of bubbling beds PLUS Large minimum size for viability, above around 15 t/h dry feed rate. High cost at low capacity. In-bed catalytic processing not easy Examples: Technical University of Vienna (development) [12], TPS [13], Lurgi [14], Foster Wheeler [15] Entrained flow Inherently simple reactor design, but only potentially viable above around 20 dry t/h feed rate and with good scale-up potential. Costly feed preparation needed for woody biomass. Carbon loss with ash. Little experience with biomass available Examples: Choren and Texaco R&D Use of oxygen Gives better quality gas. High cost of providing oxygen and high cost of meeting extra process requirements. No evidence that benefits exceed costs. Examples: There are no known current or recent examples of oxygen fuelled gasifiers High pressure gasification

95 Significant efficiency and cost advantage in IGCC applications, but large sizes are needed. Significant additional cost for pressure with smaller savings from reduced vessel and piping sizes. Examples: The most recent example is at Varnamo (Foster Wheeler and Sydkraft) which finished operation in 2000 [16], Carbona [10]

[1] M. Walker, G. Jackson, G.V.C. Peacocke, Small scale biomass gasification: development of a gas cleaning system for power generation, in: A.V. Bridgwater (Ed.), Progress in Thermochemical Biomass Conversion, Blackwell Scientific Publications, Oxford, UK, 2001, pp. 441–451. [2] UK DTI New Review No. 35, see website: http://www.dti.gov.uk/ NewReview/nr35/html/gasifier.html. [3] H.A.M. Knoef, A.V. Hunnik, A. van Pourkamal, G.J. Buffinga, Value engineering study of a 150 kWe downdraft gasification system, Final Report For: Shell Renewables and Novem, May 2000. [4] Fluidyne, see “Fluidyne Special Project.pdf” downloadable from web-site: http://www.fluidynenz.250x.com/anniversary.htm. [5] The System Johansson Gasifier, see web-site: http://www. eskomenterprises.co.za/Casestudies/TSIcases/systemjohansson.htm. [6] R. McLellan, Design of a 2.5 MWe biomass gasification power generation module, ETSU Report B/T1/00569/REP, AEA, Harwell, UK, 2000. [7] See website http://www.volund.dk/rd2.html. [8] E. Kurkela, PROGAS—gasification and pyrolysis R&D programme 1997–1999, in: K. Sipila, M. Korhonen (Eds.), Power Production from Biomass III, Gasification & Pyrolysis R&D&D for Industry, VTT Symposium, Vol. 192, VTT Espoo, 1999. [9] See website: http://www.energyproducts.com/EPISearchPage.htm. [10] K. Salo, A. Horwath, Minnesota agri-power project (MAP), in: K. Sipila, M. Korhonen (Eds.), Power Production from Biomass III, Gasification & Pyrolysis R&D&D for Industry, VTT Symposium, Vol. 192, VTT Espoo, 1999. [11] J. De Ruyck, G. Allard, K. Maniatis, An externally fired evaporative gas turbine cycle for small scale biomass CHP production, in: P. Chartier, et al. (Ed.), Proceedings of the Ninth European Bioenergy conference, Pergamon Press, Oxford, 1996. [12] H. Hofbauer, R. Rauch, Stoichiometric water consumption of steam gasification by the FICFB-gasification process, in: A.V. Bridgwater (Ed.), Progress in Thermochemical Biomass Conversion, Blackwell Scientific Publications, Oxford, UK, 2001, pp. 199–208. [13] L. Waldheim, M. Morris, M.R.L.V. Leal, Biomass power generation: sugar cane bagasse and trash, in: A.V. Bridgwater (Ed.), Progress in Thermochemical Biomass Conversion, Blackwell Scientific Publications, Oxford, UK, 2001, pp. 509–523. [14] H. Vierrath, C. Greil, Energy and electricity from biomass, forestry and agricultural waste, in: S. Kyritsis, A.A.C.M. Beenackers, P. Helm, A. Grassi, D. Chiaramonti (Eds.), Proceedings of the First World Biomass Conference, Proceedings the First World Conference and Exhibition on Biomass for Energy and Industry, James & James, 2001. [15] J. Nieminen, Biomass CFB gasifier connected to a 350 MWth steam boiler fired with coal and natural gas— THERMIE demonstration project in Lahti, Finland, in: K. Sipila, M. Korhonen (Eds.), Power Production from Biomass III, Gasification & Pyrolysis R&D&D for Industry, VTT Symposium, Vol. 192, VTT Espoo, 1999. [16] K. Ståhl, M. Neergaard, J. Nieminen, Final Report: Värnamo demonstration programme in: A.V. Bridgwater (Ed.), Progress in Thermochemical Biomass Conversion, Blackwell Scientific Publications, Oxford, UK, 2001, pp. 549–563.

96 Appendix II, Pilot plants with gasifier

Viking Gasifier, at Lyngby, Denmark The Viking plant was commissioned in mid-2002 and in October 2003 more than 2000 hours of operation with wood chips as fuel had been conducted. The plant is a small-scale gasifier with a nominal thermal input of 75 kW. The gasifier and engine have been operated continuously and unmanned for five test periods of approximately 450 hours each. All information regarding the Viking Gasifier is adopted from IEA Biomass Media Centre [50]. Fuel Cooled exhaust

6 Drying and pyrolysis 50 C 600 6 C 3 50,000 mg/Nm tar

Partial oxidation > 1100 6 C Electricity Exhaust

3 Engine 500 mg/Nm tar Mixing tank Gasification Roots blower Gas 750 6 C 3 < 5 mg/Nm tar 50 6 C 90 6 C D.H. D.H. Ash Condensed Exhaust Particles water Air preheat superheat

3 < 1 mg/Nm tar

Figure 55: Process diagram for the Viking pilot plant

Technology The Viking plant (see process diagram above) is based on the two-stage gasification process developed by the Technical University of Denmark. In this process the pyrolysis and gasification reactions which take place in two separate reactors are thermally integrated to decompose the tars and to improve the overall process efficiency.

The 600°C hot pyrolysis products are partially oxidised by preheated air. This partial oxidation results in a temperature increase to around 1100°C at which most of the tar is decomposed. The Viking plant uses thus thermal cracking. The raw gases are cooled in heat exchangers, delivering heat for the process and for district heating. The produced gas is cooled to 90°C and at this temperature the soot particles are removed dry in a simple bag house filter.

Upon further cooling, the steam contained in the gas is condensed. The toxicity of the condensate has been tested and the material is acceptable for processing in Danish biological sewage plants. The cooled gas is fed to a gas engine coupled to a generator, producing power and district heating.

The gas engine is an integrated part of the whole gasification plant. The excess heat from the exhaust gas is utilised for drying and pyrolysis of the biomass in the gasification system, and the engine directly controls the load of the gasifier.

Plant Performance Data Thermal input 68 kW Fuel Wood chips Moisture content 35-45 % Gasifier efficiency 93% Engine efficiency 32% Electric efficiency 27% Overall elect. eff. 25% Tar level <1 mg/Nm3 Dust level <5 mg/Nm3

In April 2003 three independent institutes measured the tar content in the raw and cleaned gas. Only one of them was able to measure a minor content of tar in the raw gas (0.1 mg/Nm3 of naphthalene). The dust content in the gas was also negligible (< 5 mg/Nm3).

Based on the experience obtained during operation of the Viking gasifier it is concluded that the plant is easy to operate and control. So far, no problems with metal corrosion have been observed.

The scale-up of the two-stage process to large capacity plant activities is planned to start in 2004 in co-operation with private companies.

Figure 56: Viking gasifier at DTU, Copenhagen, Denmark

Arbre Project ARBRE is an 8 MWe state-of-the-art wood-fuelled combined-cycle plant in Eggborough, North Yorkshire, UK. The operation of the plant started in 2001. The references are Morris et.al. [57] and Pitcher et.al. [58].

Technology The wood is delivered to the plant in chipped form and tipped into a fuel reception building, which provides three days bulk storage. The fuel is dried to around 10% moisture content with flue gases leaving the waste heat boiler. The dried fuel is then fed to the gasifier. The wood is converted into a low calorific value gas (heating value = c. 5 MJ/Nm³) by gasification in a Termiska Processer (TPS) air-blown circulating fluidised bed (CFB) gasifier operating at around 850°C and close to atmospheric pressure.

Figure 57: Process diagram for the Arbre BIG-GT project

The gas produced in the gasifier is cleaned of tars in a tar cracker; a second CFB operating at a slightly higher temperature with dolomite as bed material. TPS's gasification technology had already been proven at commercial scale in two 15 MWth waste-fuelled gasifiers in Grève-in- Chianti, Italy, but although the tar cracker has been demonstrated at pilot plant scale over a number of years, its use in the ARBRE plant is the first time it has been demonstrated at commercial scale. In the cracker, the tars are cracked catalytically to simpler compounds. By converting the tar in the gas in this way, the gas can be cleansed of particulates and alkalis in conventional gas cleaning equipment. In addition, this catalytic process means that there is no

99 significant reduction in the chemical heating value of the gas, as would be the case if the tar was thermally cracked at higher temperature. After leaving the tar cracker, the gas is cooled before being passed through bag filters at typically 200°C to remove fine particulates (fly ash, alkalis condensed on fly ash and chloride as CaCl2). The gas is then cooled further before the final cleaning stage. The heat removed during the gas cooling stages is recycled for boiler feed water pre-heating and steam production. The final cleaning stage is a wet low temperature scrubbing procedure to condense out any remaining tars and water vapour and remove traces of alkali metals, as well as removing ammonia using a dilute sulphuric acid solution.

The resulting clean gas is now split into two streams and fed to the combined-cycle generating plant. The main gas stream is compressed and fed to the Typhoon gas turbine, which has a rated output of 4.75 MW. The hot gas turbine exhaust gases are then passed to a boiler for heat recovery and steam generation. The Typhoon single-shaft industrial gas turbine is designed specifically for electrical power generation and cogeneration applications. It application to biomass-produced fuel gas was proven in the Värnamo wood-fuelled pressurised gasification plant in Sweden. The second gas stream is combusted in the boiler to supplement the gas turbine exhaust heat and generate additional steam. The steam raised in the boiler is now combined with that produced in the gas cooler and used to drive a 5.25 MW steam turbine. The steam leaving the steam turbine is then condensed in a hybrid cooling plant and returned to the boiler.

Feedstock The plant requires 41 500 dry ton of biomass each year. This is mainly delivered from the local (within 50 miles radius) short rotation coppices (SRC) which are harvested every third year (1700 ha). Also forest residues are used when they are available.

First Renewalbe Ltd., Termiska Processer and Alstom Power have developed preliminary plans to build a series of plants in the UK similar to the Eggborough plant but at 30 MWe capacity. For these plants, Alstom Power plans to develop their 14 MWe Cyclone gas turbine. With plant capacities of 30 MWe and higher, net electrical efficiencies of more than 40%, and close to 50%, can be achieved. It is also predicted that as biomass-fuelled IGCC technology becomes more mature, the capacity of the plants built will increase and, together with future developments to the gas turbine and the results of continuous systems optimisation, the capital cost of the plants can be reduced to 1 500 Euro/kWe.

100 Appendix III, Research in the field of biofuels in Norway 2005 There are two projects given economical support from “Forskningsrådet” in Norway:

! “Cost efficient production of renewable liquid biofuels and biochemicals from Scandinavian wood materials”. The project started july 2005 and is finished December 2008

! “Pre-study: Production and use of synthetic fuels (BTL) in Norway” The project started august 2005 and is finished autumn 2006

101