R OYAL ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION C MISO ON OMMISSION

E NVIRONMENTAL as a

P Renewable OLLUTION Energy Source Biomass as a Source About the Royal Commission on Environmental Pollution

The Royal Commission on Environmental Pollution is an independent standing body established in 1970 to provide authoritative advice on environmental issues. Its terms of reference are:

To advise on matters, both national and international, concerning the pollution of the environment; on the adequacy of research in this field; and the future possibilities of danger to the environment.

Within this remit the Commission is free to consider and advise on any matter it chooses; the UK government or the devolved administrations may also ask it to consider particular topics.

The primary function of the Commission is to contribute to policy development in the longer term by providing a factual basis for policy-making and debate, and setting new agendas and priorities. It considers the economic, ethical and social aspect of issues alongside the scientific and technological aspects. It sees its role as reviewing and anticipating trends and developments, identifying fields where insufficient attention is being given to environmental problems, and recommending actions that should be taken. The Commission has published 24 reports, and many of their recommendations have been accepted and implemented by successive governments.

The members of the Commission have a wide range of expertise and experience in natural and social sciences, medicine, engineering, law, economics, and business. They serve part- time and as individuals, not as representatives of organisations or professions.

A full-time Secretariat supports The Chairman and Members by arranging and recording meetings and visits; gathering and analysing information; handling finances and administration; and drafting and publishing the Commission’s reports.

In the course of its studies, the Commission canvasses a wide range of views. Information on its work (including minutes of meetings, background papers by consultants and summaries of evidence submitted) is available via www.rcep.org.uk. BIOMASS AS A RENEWABLE ENERGY SOURCE A Limited Report by The Royal Commission on Environmental Pollution

Contents Page

CHAPTER 1 – Introduction 3 CHAPTER 2 – Biomass fuels 9 Energy crops 9 Forestry products 21 Sawmill co-products 24 Municipal arisings 26 Conclusions 28 CHAPTER 3 – Generation using biomass fuels 30 General principles 30 Heat generation 31 Combined heat and power 33 40 Environmental implications 43 CHAPTER 4 – Meeting the target 47 Economics of biomass 47 Transport 52 Energy conversion facilities 58 Land-take 60 Planning for biomass 63 Phased delivery 67 A strategic approach 68 CHAPTER 5 – Conclusions and recommendations 69 APPENDIX A – Policies to support biomass – description of current 72 schemes APPENDIX B – Case studies 75 APPENDIX C – Scope and limitations of the special report 83 APPENDIX D – Conduct of the report 85 APPENDIX E – Members of the Commission 88 APPENDIX F – Reports by the Royal Commission on Environmental 89 Pollution REFERENCES 90

ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 1 2 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE CHAPTER 1 – INTRODUCTION

Context 1.1 Energy consumption throughout the world, but particularly in industrialised societies, has been steadily increasing. Much of the energy consumed, 97% in the case of the UK1, comes from non-renewable sources. The present use of carbon-based non-renewable energy is unsustainable, inter alia because of the effect of the resultant carbon dioxide (CO2) emissions on the global climate. Reduction in demand must be part of the solution2 but alternative energy sources must also be developed. All energy sources come with environmental penalties, whether from the construction of dams and barriers or from the impact of renewable sources such as wind on rural landscapes, but these impacts must be balanced against the necessity of developing low-carbon sources that are both economically viable and also secure.

1.2 The Royal Commission’s Twenty-second Report, Energy - The Changing Climate published in 2000, advocated a number of steps that the government should take, both in terms of domestic policy and through international negotiation. A key recommendation was that a long-term target should be set to reduce CO2 emissions by 60% by 2050. This was based on the contention that the maximum concentration of CO2 in the atmosphere should not exceed twice the pre-industrial level. The government subsequently accepted that the UK 3 should put itself on a path towards this aim . In order to reach a 60% reduction of CO2 emissions, it is vital for the government to concentrate on encouraging low- or non-carbon electrical and heat generation. As a component of a renewable energy generation mixture, biomass should play an important role.

1.3 There are three types of indigenous biomass fuel: forestry materials, where the fuel is a by- product of other forestry activities; energy crops, such as short rotation coppice (SRC) willow or miscanthus, where the crop is grown specifically for energy generation purposes; and agricultural residues, such as straw or chicken litter. Biomass can also be imported, mainly in the form of pelleted sawdust (which is already an internationally traded commodity).

Why Biomass? 1.4 Wood is a renewable fuel; its production and use is almost carbon neutral. Trees absorb CO2 to photosynthesise organic compounds using solar energy. The energy is stored chemically and released when the wood is subsequently destroyed - whether by natural decay or combustion. Hence, although CO2 is released into the atmosphere when wood is burnt, an equivalent amount of CO2 has been taken from the atmosphere during growth. Some net release of CO2 would take place if the growing, processing or transporting of the wood involved the use of fossil fuel.

1.5 The carbon in biomass used as fuel does not therefore contribute to greenhouse gas emissions. Technically emissions from biomass use are reported in the UK greenhouse gas

ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 3 inventory as a memo item, but are not included in the national total. This is in accordance with international guidelines from the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Framework Convention on Climate Change (UNFCCC). On the other hand emissions of nitrous oxide and methane from the combustion process are included in the national total (because the carbon is balanced by photosynthetic uptake but the methane and nitrous oxide are not). Emissions of nitrous oxide from any fertiliser used to grow the biomass are also included, as are emissions of CO2 from fossil fuel used in forest or field operations and transportation.

1.6 Unlike most other renewable energy sources biomass can be stored and used on demand to give controllable energy. It is therefore free from the problem of intermittency, which is a problem for in particular. Also, unlike most other renewable sources, biomass offers potential as a source of heat as well as electricity, offering high conversion efficiencies. This potential appears to have been overlooked in government policies to promote biomass, which have concentrated on electricity generation. In this report we therefore concentrate on biomass as a fuel for heat or combined heat and power (CHP) . We will show that biomass energy offers an opportunity to rethink energy generation and to drive a step-change in the efficiency of power and heat production. The implications for the UK’s CO2 reduction targets are highly significant.

1.7 Biomass energy technology is inherently flexible. The variety of technological options available means that it can be applied at a small, localised scale primarily for heat, or it can be used in much larger base-load power generation capacity whilst also producing heat. Biomass generation can thus be tailored to rural or urban environments, and utilised in domestic, commercial or industrial applications.

Box 1A Units of energy production

Rates of production of energy are measured in watts (or kilowatts (kW), megawatts (MW) or gigawatts (GW)). If a production rate of one watt is maintained for one hour, the amount of energy produced is one watt-hour.

This report uses watts and the units derived from watts to indicate energy generally. Where it is important to distinguish heat (thermal energy) from power (electrical energy) a suffix (th or e, respectively) is used. For example a CHP facility with a total output of 40 MW might typically produce 30 MWth and 10 MWe.

1.8 The technology is most efficient where a source of fuel and a demand for heat are within an economically viable distance of each other. In this report we examine the costs of transporting biomass fuels, both financially and in terms of CO2 emissions. We show that we might expect a significant proportion of the UK to be able to meet the maximum distance criterion for efficient use of biomass. In some areas of the UK fuels could be grown as energy crops and in others it would arise as a by-product of agriculture, forestry and other activities.

1.9 Biomass offers important opportunities for UK agriculture and the countryside. As the North Sea resources become exhausted, the shift from to oil and gas-fuelled generation

4 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE means that most of our fuels will come from outside the UK. This dependence on international sources for our fuel reduces security of supply and marginalises the domestic agricultural sector. Biomass energy provides an opportunity to develop a fuel source from the UK’s own resources, increasing the security of its energy supply; it also offers new opportunities for UK agriculture.

Why not biomass? 1.10 Biomass has been successfully used as a source of energy across Europe but it has not become established in the UK; there are several reasons for this. The main problem is that the government’s capital grants schemes for biomass initiatives have focussed on high- technology approaches to electricity-only generation with a view to potential export development. Demonstration schemes have not been based on established biomass technology and they have consequently failed, with resulting loss of confidence. The failure to recognise heat utilisation as an important way of delivering high-efficiency energy means that opportunities have been lost. Climate change policy, not speculative export possibilities, should be the primary driver for developing the biomass sector in the UK.

1.11 Additionally, the complexity of grant schemes has made it difficult to make headway into developing this sector. In this study we identified 14 different grant schemes, but found no national co-ordination. Similarly there is no national facility for the sharing of information and experiences on biomass. At present it is too difficult for the biomass sector to grow and government policies that are meant to make this process easier fail to do so.

1.12 These problems however are institutional rather than technical. There is no fundamental reason why the UK biomass industry should not follow the route that has proved to be successful in countries such as Sweden, Denmark, Austria and New Zealand. However, growth of energy crops requires water and land and can have implications for biodiversity and landscapes.

1.13 In this report we address these issues and discuss how they are likely to affect the take-up of energy crop production in the UK. Any extensive use of biomass could also have significant transport implications, and planning must allow for and minimise the associated costs and impacts.

1.14 Combustion of biomass generates gaseous emissions and considerable quantities of ash, some components of which (such as dioxins and heavy metals) are potentially harmful. This report discusses these emissions and makes recommendations for the reduction of emissions and the handling of solid wastes.

Strategy

Targets 1.15 This study was carried out following the publication of the Energy White Paper, which accepted a number of the recommendations in our Twenty-second Report. Here we expand

ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 5 upon those recommendations and offer policy-based guidance on how to achieve them. In particular we recommended that by 2050 up to 16 Gigawatts (about 12%) of the nation’s energy should come from biomass (Table 1.1). This would be a clear but not dominant role for biomass within a larger, diversified energy portfolio. Our Twenty-second Report illustrated four possible scenarios for the future of UK energy generation, all of which required some degree of biomass generation to meet the 60% CO2 reduction target. Table 1.1 summarises the contributions required from biomass as set out in the four scenarios in the Twenty-second Report.

Table 1.1 - Biomass targets from the Twenty-second report

Scenario Biomass Total UK Biomass as % of total GW GW GW

1 16 205 8

2 16 132 12

3 7.5 132 6

4 3 109 3

Environmental, social and economic implications 1.16 This report describes the agronomic, technological and infrastructure developments that would be needed to deliver sufficient energy from biomass. In doing so, it discusses the environmental, social and economic implications of each component.

Environmental 1.17 Setting aside the savings in CO2 emissions, which are common to all renewable energy sources, the production and use of woody biomass as an energy source will have both positive and negative effects on the environment. While these may be difficult to quantify, we have seen evidence that the net impact will be positive. Experiences in countries such as Austria and Sweden where use of biomass is well established are particularly encouraging. Given the limited experience in the UK, it is important that care is taken to learn from experience elsewhere to minimise adverse effects. Environmental impact assessments should be carried out and the evidence reviewed at each stage of the development of a biomass energy sector.

Social 1.18 Experience in Austria and Sweden has shown that if biomass energy is introduced sensitively and transparently, society welcomes it. Local concern may well arise if people see evidence of large-scale landscape changes as energy crops are introduced, or are not

6 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE satisfied that the local impacts of energy generating plants have been properly addressed. However, guidance and standards are available to address these concerns, and it is important that these are carefully applied.

Economic 1.19 We have also considered the cost of biomass energy. The cost of the fuel is comparable to that of fossil fuels (particularly when the external costs of CO2 emissions are taken into account), but the capital investment required is generally higher. In addition the grant structure to support biomass utilisation is both complex and incomplete when compared to the support available to other forms of renewable energy. It is not well suited to supporting an energy source that delivers heat as well as electrical power. There is a need to stimulate markets for heat, and there are opportunities now to do this. We have made recommendations to address this.

A staged approach 1.20 A successful biomass energy strategy requires that by 2050 much of the fuel needed will be grown as energy crops, and this means that potentially significant amounts of agricultural land will need to be diverted to this use. However, in the shorter term there are existing sources of biomass to fuel the development of the sector. We have identified four stages in this process:

• Immediate future - energy crops utilise a relatively small proportion of set-aside land.

• Short-term - area required for energy crops increases to an area equivalent to the amount of set-aside land.

• Medium-term - area required for energy crops increases beyond the amount of land that is currently set-aside.

• Long-term - area of land increases to be a significant proportion of total available agricultural land.

The timing of these stages and the amount of land that will ultimately be needed by 2050 for growing energy crops will depend on the availability of other biomass fuels, especially straw and forestry arisings. We consider fuel availability in chapter 2.

1.21 In chapter 3 we discuss the different approaches to converting biomass to heat and power. We question the appropriateness of the government’s current emphasis on high-tech power generation and we concentrate on the use of relatively simple heat or CHP plants, and on co-firing in existing stations – these are technologies that are already available or are close to being proven.

1.22 Chapter 4 brings our conclusions on fuel resources and conversion facilities together into a new strategy for developing a biomass utilisation programme over the next few decades, based around the four stages described above. We calculate the number of energy plants that would have to be built and the amount of land that would need to be

ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 7 brought under energy crop production, and map these onto the four-stage model. Chapter 5 is a summary of our conclusions and recommendations.

1.23 Our proposed strategy does not cover biofuels for transport or energy carriers such as hydrogen produced from hydrocarbons. As described in the Twenty-second Report and our analysis of the environmental impacts of air travel, transport is a prime user of hydrocarbons. Fuels such as bioethanol from cereals and biodiesel from oil seeds may have a role as fuels for surface transport4. Applications of woody biomass to produce transport fuels are more speculative, they are not covered in this report as we view them as longer- term possibilities that might be appropriate if surplus biomass or land is available once the more immediate applications have been exploited.

1.24 We also make the point that woody biomass gives a higher energy yield per hectare than transport fuels from cereals or oil seed crops. However, in a climate of changing policies and incentives, farmers will naturally prefer to plant annual crops rather than woody materials which require a commitment to one crop for many years. This leads to a further theme in our recommendations: that development of a biomass sector is dependent on stable long- term policy.

8 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE CHAPTER 2 - BIOMASS FUELS

2.1 Biomass for fuel can be gathered or grown. Energy crops are grown using agricultural methods; in this chapter we shall examine the main species suitable for use in the UK and the methods of cultivation, economic value and impacts through land-take, water use and soil contamination. Forestry and municipal tree management both lead to substantial arisings of woody plant material that could be gathered for fuel and we shall consider the likely arisings in the UK. The potential resources of straw from cereal and oil seed crops are also considered.

Energy Crops

Species 2.2 Willow (Salix spp.) has already been used in commercial or near commercial operations in the UK. Investment in developing new varieties with increased yield stability and improved crop management has made willow increasingly competitive as an energy source (paragraph 4.2). Willow chips are a reliable source of fuel of a consistent quality, suitable for firing in CHP and district heating plants. Willow has been grown extensively in Scandinavia for fuel, and in Sweden some 15,000 hectares of land are dedicated to its production for renewable energy. Consequently, much more information about cultivation, harvesting and yields is available for willow than for the other potential energy crops. The grass miscanthus (Miscanthus spp.) is attracting an increasing amount of interest but it is still largely at trial stage in the UK.

2.3 Among other potential candidate species, poplar (Populus spp.) is closest to providing an alternative source of fuel. Poplar is being trialled in short rotation coppice (SRC) plantations, as well as being tried in silvoarable agro-forestry where it is intercropped with arable species. Straw has also been used as fuel and has the advantage of being a by-product with which farmers are familiar.

Cultivation, harvesting and yield

Willow 2.4 Short rotation coppicing (SRC) is the most promising way of growing willow quickly and easily. Breeding programmes are continuously developing new varieties that have higher yields, better growth characteristics (straighter stems for easier harvesting for example), and more resistance to pests and pathogens. Willow is easy and relatively inexpensive to plant using cuttings. The stems are cut into 2 metre lengths before transportation (they can be frozen if travelling long distances). A Swedish company5 has developed a step-planter that cuts the stems into 15cm sections and deposits them in the soil. They are then pushed further into the soil with a roller and left to take root.

ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 9 2.5 The first year of growth is cut back to encourage rapid, thick growth in the second to fourth years. The willow is ready for harvesting and chipping after three years of regrowth. The stems are cut above ground level and the stumps are left to reshoot. An average willow coppice can be harvested over 15-20 years and the land can readily be returned to conventional crop use in 1-2 years by ploughing in the roots and treating the soil and weeds with herbicide.

2.6 Willow is capable of benefiting areas with loose topsoil because its roots grow into a mat- like mass immediately below the surface of the soil, which helps to retain the topsoil. The leafy canopy prevents saturation of the land during periods of heavy rainfall, reduces soil erosion from run-off and prevents nutrients from entering streams.

2.7 Levels of pest or pathogen damage that are considered unacceptable in food crops can be tolerated in plants that are destined to be burned. Consequently, established SRC can be managed with few pesticide applications without incurring significant economic penalties. Integrated Pest Management (IPM) has been addressed mainly for willow, but a number of the recommendations could be extended to poplar. The resistance of willow genotypes to infestation by various pests and pathogens is well understood, as are site-dependent factors such as plants present in adjacent areas that might act as hosts to divert fungal diseases. IPM for willow SRC recommends the planting of up to five varieties of different ages in a plantation to enhance biodiversity. It also recommends strategic planting to concentrate pests and pathogens in smaller areas of coppice, reducing the scale of chemical application needed to control the pests6. Rabbits are a pest that cannot be controlled through the use of IPM, they can pose a significant threat to willow shoots and rabbit-proof fencing is costly, especially on irregularly shaped plots of set-aside land with high boundary to area ratios.

2.8 The emphasis, when planning SRC plantations, should be on utilising local knowledge and planting varieties that have been tested previously on a similar site. Tailoring the plantation to the local environment is essential. Attention to detail at the planning phase can result in well-designed, healthy coppices with high yields, low disease and pest susceptibility and improved biodiversity.

2.9 Conventional willow harvesting machinery cuts and chips the stems simultaneously. By planting the willow in rows, high chipping rates can be achieved. It is important to harvest willow in winter as it results in better wood with lower water content and allows nutrient cycling from fallen leaves. The harvesting equipment that has been used so far is based on that used in Sweden. There, willow is harvested in winter and the frozen ground makes it possible for heavy machinery to move over the land without causing excessive soil damage. In the UK the land does not freeze to the same degree as in Sweden and so this type of heavy equipment is not suitable. A UK willow growers’ group has gone some way towards solving this problem by using an imported sugar cane harvester7. There is no need for frozen soil during harvesting as the mat-like roots of the willow plants adequately support the lighter machinery.

2.10 The UK transportation infrastructure cannot yet match the rate of willow chip production, so chips would have to be stored at the side of fields and reloaded onto trucks. The cost of unloading and reloading chips for later transportation can be restrictively high both

10 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE economically and energetically, and storage times and methods need to be controlled to avoid the development of fungi leading to biodegradation, and the build up of excessive moisture.

2.11 The cane harvester used in the plantations established around the Arable Biomass Renewable Energy (ARBRE) plant (paragraph 3.35) harvests the wood in rod form, which is easier to transport and store and has a higher bulk density with lower moisture content. Storing the materials in rod form also reduces the loss of material and calorific value due to

Coppiced poplar wood chips in farmer’s hands decomposition during long-term storage8. The rods are then chipped before use, or, if destined for use in a co-firing plant (paragraph 3.42), can be milled directly into wood dust.

2.12 UK farmers and test centres have reported varying yields for willow SRC. This variation is likely to be the result of the variable quality of the plants, suitability of the land and more or less effective management. Yield has also been found to depend on planting density and frequency of harvesting9. Farmers currently see willow as a marginal crop and will make use of subsidies by planting on set-aside land. The land chosen for set-aside is often the lowest quality land and this could also result in reduced yields. Weeding and fertilising are important in the first year of growth; if it is not carried out effectively then yield may drop. Fertilising can be important throughout the growth cycle, though the amount required for willow SRC is significantly less than for arable crops.

2.13 Climatic factors also have an impact on yield. Willow requires substantial quantities of water and suffers reduced growth in dry conditions or dry years. Wetter regions of the UK might be expected to be better suited to growing willow than others, though farmers have had successful willow crops in drier areas of the UK so it seems that other factors may also be important10. The requirements for water should be considered as part of the overall water demand when crops are to be grown to provide energy for new building developments.

ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE 11 2.14 Over the three years between harvests, the yield for willow should be ~ 20-25odt (oven dried tonnes) per hectare (but it can be higher if grown under optimum conditions with additional fertiliser and water). This can deliver an income of > £100 per hectare per year (ha/y) in addition to grants and subsidies. Under the current arrangements for grants and subsidies, the growing of energy crops is only considered to be viable at yields of 10 odt/ha/y or more11. Yields of willow at this level are achievable through careful agronomy and by building on experience. Willow is less economically viable as a fuel for electrical generation only, and in chapter 3 (paragraphs 3.4 to 3.33) we have explored ways of adding value to the crop by exploiting the potential for using it in CHP and heat-only generation plants.

Poplar and other tree species 2.15 Poplar has been trialled on a much more limited basis in the UK and results have varied dramatically from site to site. Planting of poplar is more difficult than with other energy crops because it is not easily propagated from cuttings. Good apical buds are needed for effective planting and growth. Planting machinery has not yet been developed and current practice is to use a cabbage planter; success with this machinery is limited and there is real scope for technological developments to make the process much easier and more effective. Land used for poplar is more difficult to return to normal agricultural use than that used for willow, as the deep woody roots are difficult to remove.

2.16 Willow harvesting methods are also likely to be relevant to poplar although harvesting may be needed more frequently due to the fast growing stems that thicken quickly.

2.17 Poplar trials in the UK have revealed that the yields are very site specific. In some cases poplar yield has outperformed willow by up to 66% but in others poplar yield has been as low as 30% of willow production12. The wide variation in yield, dependent on a number of site-specific factors, could prove an obstacle to wide scale adoption of poplar as an energy crop in the UK but does not rule out its use in those areas that are suited to its production.

2.18 Increasing the variety of energy crop options available to farmers enables planting to be determined by local environmental factors, which increases farmer confidence. This also enhances security of supply for generators, as farmers will be able to plant crops that are more likely to thrive in their locality thus making harvests more reliable than if only a single energy crop option were available. It is our opinion that the influence of site suitability on yield means that farmers should be allowed as much flexibility as possible when moving into biomass fuel production. Planting should be guided as much as possible by local knowledge and farmers’ experience of the type of crops that they can grow on their land, not by planting grants for specific crops. We recommend that producer group grants be extended to include producers of energy crops other than willow. We also recommend that the Scottish Forestry Grant Scheme be similarly extended to cover all possible sources of biomass.

2.19 Short rotation forestry (SRF) is another option for the cultivation of a number of tree species for energy. In SRF, trees are grown closely (as single stems) and harvested after 5-15 years. Of the many coniferous and broad-leafed species that have been trialled, ash (Fraxinus spp.) may be the most suitable, but it requires good soil that is not acidic. On

12 ROYAL COMMISSION ON ENVIRONMENTAL POLLUTION – BIOMASS AS A RENEWABLE ENERGY SOURCE poorer, wetter soils, alder (Alnus spp.) has potential. In the short term SRF is not seen as a major source of biomass for fuel, but this could change in the future.

Miscanthus 2.20 Like wheat, miscanthus (also known as elephant grass), is a member of the grass family (Gramineae) and is grown using conventional agricultural methods and harvested annually. It is gaining favour with farmers as it is planted, harvested and stored using existing farm equipment and methods. It is cut and baled with a straw baler and stored in barns. It thus requires less capital investment than willow. Farmers also have more confidence in using current farming practices. The main disadvantage of miscanthus is that it can be difficult to rehabilitate the land for other uses due to its deep root structure.

2.21 Miscanthus is a genus of about 20 species native to tropical Asia and Africa and like most tropical grasses (such as maize, but