Supply and Energy Use of Lignocellulosic Biomass

Learning diary

Student: Luiz Felipe de Castro Galizia

Number: 291362

Summary of the topics

1. Overview of biomass resources

Biomass is any organic material which has stored sunlight in the form of chemical energy and can be used as a source of energy.

Most common sources of biomass used as a source of energy are showed in the table below.

Bioenergy is a renewable source of energy made from materials derived from biological sources (living things). It is important to highlight that most of the source of biomass used to generate energy are by-products from other sources. For example, in the wood chipping in a pulp mill all the chips that are out of the range of quality can be used to be burned as a source of energy, in agriculture/forest the residues of harvester operations can be used as a source of energy as well. So they are a by-product for another process. The figure below shows the different process to convert the biomass in energy for each kind of source. It is possible to conclude that solid biomass (wood and wood by- products) is the only source that is possible to produce almost all kinds of energy, because of that forest biomass plays an important role in energy market.

2. Characterization of biomass resources

Regarding to the wood biomass there are main 3 sources that can be used to bioenergy production.

- Energy forest: Normally are plantations of short rotation species, that are managed in an intensive way to optimize the production of biomass in a short period of time.

- Forest biomass: Biomass produce in conventional forest management (focus wood production). - Whole trees for energy: Small trees harvester in pre-commercial or first thinnings. - Primary residues: Logging residues and stumps - Secondary residues: Industrial residues as Bark, Sawdust, chips and Black liquor

- Recycled wood: Used wood from Constructions, Demolition, Wooden packages that can be used as a source of energy. Each species of tree has a specific assortment regarding to biomass production (% crow, branches, trunk…) and the rates changes in a small (more biomass in the branches, foliage) or old tree (more biomass in the trunk).

Mechanization of harvester operations is a key point for forest biomass production, because it is a cost-effective way to produce it.

The composition of wood is in general 50% water when it is wet (moisture content is 50% ). When it is dried to 0% (theoretical) the water is 0% and Carbon 50%. In normal conditions after drying in the field the wood have about 30% of moisture.

There is a correlation between the heating value and moisture content, less moisture content higher is the heating value, because energy is used to dry the wood when it is burning. However, there is an optimal point, between 15% - 25% That is technical and economic feasible to dry the biomass.

There are different ways to use the forest biomass as a fuel and the best way depends of a lot of factors, like cost of operations, transport distance, amount of biomass, timing…

The figure bellow shows the different way to process the wood and compare with the oil based fuels. We can see that pellets are the most efficient way to process the wood for energy supply.

Take into account that the moisture content is very important in the energy production the storage of biomass is a key point to ensure the potential energy production. The storage of biomass in the field it is a simple and effective action to reduce the moisture content and optimize the transportation (less costs) and the heating value (increasing). Beyond the storage time, cover the biomass piles can be also a good practice to decrease the moisture content.

Heating value

Heating value is the amount of energy that can be obtained when burning. The heating value of wood depends of different factors:

- Wood density - Wood composition (oil) - Moisture content

1 M³ = 2 MW = 2.7 GJ (reference)

The tonne of oil equivalent (toe) is a unit of energy defined as the amount of energy released by burning one tonne of crude oil.

3. Production and supply chains of forest energy

The harvester operations play an important role in forest energy supply chain. Harvesting factors have to take into account:

- Accessibility to the stand - Amount and density (distribution) of biomass available in the stand - Forwarding distance - Transportation distance

There are a lot of options in biomass supply chain (transport of hole trees, chipping in the field, chipping in the factory, chipping in terminals, compact the residues), and the best option, that means the most cost-effective is going to depend of each situation and on the spatial and temporal dimensions of wood supply. However, there are some general conclusions between the option.

Roadside chipping is a “pull system”, which means that the chipping productivity affects the transportation and vice-versa. Chipping in the factory is suitable only for big scale, that the transport can be optimized, however low solid content could be a problem than can be reduced by baling.

There is a trade-of between scale of production and quality requirements of biomass. Greater scale (industry) requires less quality of biomass. 4. Plantations for energy

The fast growing plantations are an important source of biomass and they have been increasing during the last decade due to the changes in matrix energy and the looking for renewable sources of energy. Plantations could be planned where the demand for energy is, so it is make the plantation an alternative of biomass source. Normally, there is no land use change between forest and plantation, so the plantations are increasing in agriculture areas (arable areas). The table below describe the advantages and disadvantages of plantations comparing to agriculture.

Advantages Disadvantages More productivity Competition with food production Fast income More risk (lack of knowlodge) Better use/optimization of the machines Economic uncertain/market More works (local economy) Increase the carbon in the soil Less use of chemicals Diversification of products Absortion of heavy metals Less soil erosion Positive energy balance Willow (Salix) has been cultivated as an agricultural crop for bioenergy purposes in Sweden for the last twenty years and is regarded as an important crop for the production of wood fuel for the Swedish energy sector. Sweden is the leader in commercial plantations of short rotation willow in Europe. Areas planted included most of the traditional agriculture lands of the country. They still researching and breeding improvement that produces more vigorous than the older clones, which resulted in shorter rotations and more resistance to frost and diseases. Average yield is 10 t dm/ha/a.

It is possible to plant willow with other tree species, for example Spruce, so the willow can be harvester 3 or 4 times before the Spruce takes over the land area. This is an option to reduce the negative impacts in the decrease of timber production.

Harvest during winter to supply the seasonal heating demand, it is also good in the point of view the machines and compaction of soil. In the harvester process the trees are cut and chipped simultaneously. Short transport distance is important. Bundles are also used to compact the biomass and can be an option.

5. Management of SRF plantations for ecosystem services

The Short Rotation Coppice (SRC) plantations are also important for the ecosystem. Plantations can be simultaneous cultivation of SRC / trees and other (annual) crops on the same piece of land, and be planted in the worst agriculture areas (less productive, format and slope of plots unfavorable for agriculture practice). Those plantations can also be used of nutrient-rich residues of society (as municipal wastewater and sludge) to fertilize fast- growing tree species (willows and poplars) to produce biomass for energy. Spreading of sewage sludge and wood-ash in SRC is very common in Sweden

6. Methods for resource and environmental assessment

Life Cycle Assessment as a tool to analyze products, processes or services from an environmental perspective. It is included the system description, system boundaries and scenarios, the parametrization of all process of production and inventory. LCA can be used to compare different productions process and gives a wider perspective of all process chain and impacts in the environment.

7. Estimating potential of bioenergy production

Theoretical potential it is the estimation of upper limit production of particular source, so does not take into account the land use restrictions, efficiency of conversion technologies and others factors. It is more general and give us an idea of the importance of particular source. Normally we can use national inventories or GIS and remote sensing tools to collected data.

Technical potential is more detailed, take into account the specifically the conversion factor of each technology in the process of production and can be also consider also the land use restrictions and environmental restrictions.

Economic potential is more close to the reality, because included the production costs, efficiency and could be used to compare with other products.

Sustainable potential takes into account all dimensions of sustainability (social, economic and environmental). It is not well defined.

- Local potential, high detail, spatial component (soil fertility, weather conditions,) - Regional potential, medium detail, semi-spatial component - Global potential, low detail, no spatial component (more assumptions)

In all potential estimations the researcher must transform data available in information.

8. Estimating heat demand

There is a correlation with the size of population and the amount of heat demand that is needed. Temperature along the year also impact in heating demand. The equation above simplifies the factors that can be used to estimate the heat demand.

Total energy = Population x m²/capita x HDD x Efficiency (technology efficiency)

Population = gives the amount of people

M²/capita = size of the areas (there is a correlation between size of the houses and GPD per capita)

HDD = Heating degree day

Efficiency = Takes into account the efficiency of technologies, isolations factors…

Central heating plants are growing in Finland. The table below describes some characteristics.

Advantages Disadvantages More energy efficient (conversion of Less atractive in low dense population biomass in heating is high) areas

Termal heat recover Higher investiments in tube connections

Renewable energy source Long term compromisse

Good for local economy Risk of changes in the eletricity price Cheaper than eletricity Needs a central planning Planning a new bio oil mill requires an analysis of a lot of factors, so the modelling of operational costs provides an important tool to understand the factors and optimize the production of bio-diesel fuel. Simulations of the production costs shows that the conversion efficiency and investment costs are the most important factors and should be improve to reduce the production costs. The energy wood cost and plant size are the next most important factors in this analysis.

The comparison between bioenergy production in India, Poland and Finland is resumed in the table below. India Poland Finland Product Eletricity Eletricity + Heat Eletricity + Heat

Plants Biomass Cofiring CHP

Feedstock agro biomass agro biomass forest biomass Supply chain Low Medium High technological level Convertion factor 20% 90% (35% eletricity + 55% heat) 90% (35% eletricity + 55% heat)

Rival source of energy - Coal Peat, oil

Obligation to purchase green Energy price controlled by government, Market certificates (or pay compensatory Subsidy but biomass price fluctuate (risk) payment) Napier grass, leucena, jatropha New biomass source - Willow and SRC plantations Strong forest market (biorefinary Optimization of agricultural residues Future development CHP industrial clusters capturing the synergies in a mill (pellets,..) complex) 9. Technology behind conversion processes

Harvested biomass can be converted into gas, liquid and solid fossil fuel resources. Combustion is simply the process of burning for heat. Co-firing is another form of combustion and is used to describe a facility where biomass is combusted in varying proportions along with coal or other feedstocks such as tire-derived fuel. Combined heat and power production (CHP) utilize the simultaneous production of heat and electrical energy, thus increasing fuel efficiency.

Different for others renewable source of energy biomass is able to supply a wide range of carbon based products with material qualities, such as liquid fuels, lubricants and a wide range of petrochemical substitutes.

First generation biofuels are mainly bio-ethanol and biodiesel. They have a low conversion efficiency (only a small portion of the biomass is converted to fuel) and high production costs. Also there is competition with others wood products like pulp, paper, timber.

Second generation biofuels are one “hot topic” that aims to use massive low cost resource and be sustainable, without competition with food production because the feedstock are residues.

There are six generic biomass processing technologies based on:

1. direct combustion (for power),

2. anaerobic digestion (for methane rich gas),

3. fermentation (of sugars for alcohols), 4. oil exaction (for biodiesel),

5. pyrolysis (for biochar, gas and oils) and

6. gasification (for carbon monoxide (CO) and hydrogen (H2) rich syngas).

Technologies for biomass processing (thermal)

- Combustion: thermal conversion of organic matter with an oxidant (normally oxygen) to produce carbon dioxide and water. The oxidant is in stoichiometric excess, over 900 °C. This method is most used for using wood for heat and energy.

- Gasification: thermal conversion of organic materials at elevated temperature and reducing conditions to produce primarily permanent gases, with char, water, and condensablesas minor products. It is carried out at 800 –1000 °C.

- Pyrolisis: thermal conversion (destruction) of organics in the absence of oxygen, causing the biomass to decompose. This is the lower thermal process producing liquids as the primary product. There are two kinds of pyrolysis: fast pyrolysis, which takes place in less than two seconds with temperatures between 300 and 550 °C ; slow pyrolysis, which can be optimized to produce substantially more char than fast process, but takes on the order of hours to complete.

Personal conclusion about the course

This course was very important for understand better the biomass supply chain and identify the main elements of the production aspects of various forms of biomass.

I would like to share some reflect about the main source of forest biomass in my country, Brazil. Brazil is the country with the higher productivity of Eucalyptus plantation in the world and considering that it Is possible to improve even more the productivity if we adapt the management for bioenergy production, Eucalyptus plantations could be more profitable and become an important source of bioenergy. I believe also that bio-oil are going to be a good alternative for substitution of oil based products.

However, for biomass production be implement in large scale we need policy and market for this new products and after the discovery of pre-salt oil reserve in Brazil, unfortunately there are not many policy regarding to new renewable energy production. In other hand there is a commitment with UNFCCC to look for a renewable energy and I hope my country fulfills this commitment to help the world walk towards the sustainability.