Sustainable biofuels: prospects and challengesSustainable biofuels: prospects January 2008 The Royal Society RS Policy document 01/08 Sustainable biofuels: prospects and challenges Policy document 01/08 January 2008 ISBN 978 0 85403 662 2 This report can be found at royalsociety.org Cover image: splash of liquid. Copyright © Stockxpert Sustainable biofuels: prospects and challenges ISBN 978 0 85403 662 2 © The Royal Society 2008 Requests to reproduce all or part of this document should be submitted to: Science Policy Section The Royal Society 6–9 Carlton House Terrace London SW1Y 5AG Email: [email protected] Typeset by The Clyvedon Press Ltd, Cardiff, UK Sustainable biofuels: prospects and challenges Contents page Summary 1 1 Introduction 5 1.1 Wider context 5 1.2 The study 7 2 Feedstock 9 2.1 Overview 9 2.2 Diversity of feedstocks 10 2.3 Land use and ecosystem issues 13 2.4 Research and development for feedstock improvement: current strategies 15 3 Conversion and biorefineries 19 3.1 Overview 19 3.2 Supply, preparation and pre-treatment of raw materials 20 3.3 Bioethanol and biobutanol production 23 3.4 Biodiesel 24 3.5 Synthetic biofuels 25 3.6 Biorefineries 28 3.7 Developments 29 4 End use and distribution 31 4.1 Overview 31 4.2 Relative differences between different fuels and their usage 32 4.3 Fuel standards and specifications 33 4.4 Engine modifications and performance 34 4.5 Atmospheric emissions from the use of biofuels 35 4.6 Conclusions and recommendations 36 5 Evaluating the impact of biofuels 37 5.1 Overview 37 5.2 Life-cycle assessment 37 5.3 Limitations and opportunities in life-cycle assessment 38 5.4 Biofuels and greenhouse gas emissions 39 5.5 Land use 40 5.6 Water consumption 42 5.7 Wider pollution issues 45 5.8 Biodiversity 46 5.9 Conclusions and recommendations 47 6 Policy 49 6.1 Wider policy context 49 6.2 Commercial motivations and innovation 49 6.3 Energy security and mitigation of climate change 50 6.4 Climate change and land use 51 6.5 Policy instruments for biofuels 52 6.6 Transport fuels and transport policy more generally 53 6.7 Policy and research 54 6.8 Public dialogue and communication 54 6.9 Conclusions 55 The Royal Society Sustainable biofuels | January 2008 | iii 7 Research and development 57 7.1 Feedstocks 57 7.2 Conversion and biorefineries 58 7.3 End use and distribution 59 7.4 Evaluating environmental impacts 59 7.5 Policy 59 8 Conclusions and recommendations 61 References 65 Working group membership 73 Annex 1 Abbreviations and glossary 75 Annex 2 Call for evidence response and workshop attendees 79 iv | January 2008 | Sustainable biofuels The Royal Society Summary Sustainable biofuels, prospects and challenges efficiency, as well as moderating the demand and need for transport. Given that biofuels are already in the market, Our climate is changing and there is now scientific, social however, it is vital that policies that promote biofuel and political recognition that this is very likely a development also address the environmental, economic consequence of increasing anthropogenic greenhouse and social impacts, so that they are made to perform their gas (GHG) emissions. Transport now accounts for about task effectively. Our conclusion that biofuels are potentially 20% of global anthropogenic carbon dioxide emissions an important part of the future is therefore tempered with and 25% of emissions in the United Kingdom (UK), and the following caveats: these figures are growing faster than for any other sector. If the UK is to reach its target of reducing emissions by • First, the term ‘biofuel’ covers a wide variety of 60% by 2050 then cuts will need to be made in the products with many different characteristics and a transport sector. wide range of potential savings in terms of greenhouse gas emissions: each biofuel must be However, access to energy underpins our current way of assessed on its own merits. life and the hopes of peoples around the world for improved lives. Mobility is a core component of these • Second, each assessment must address the aspirations. Transport has become the main driver for environmental and economic aspects of the increasing global primary oil demand, which is predicted complete cycle – growth of the plant, transport to to grow by 1.3% per year up to 2030, reaching 116 the refinery, the refining process itself (including million barrelsa per day (up from 84 million barrels per day potential by-products such as specialty chemicals), in 2005). The transport sector in particular relies almost wastes produced, distribution of the resultant fuel entirely on oil, which is predicted to become increasingly to consumers, end use, and potential for pollution. scarce and costly in the next few decades and supplies of Such assessments would help to determine the extent which are vulnerable to interruption. to which different biofuels are carbon neutral. Biofuels – fuels derived from plant materials – have the • Third, widespread deployment of biofuels will have potential to address these two issues. At first sight they major implications for land use, with associated appear to be carbon-neutral (the carbon they emit to the environmental, social and economic impacts that atmosphere when burned is offset by the carbon that must in turn be assessed. Here, in particular, plants absorb from the atmosphere while growing), unintended consequences may reduce or override renewable (fresh supplies can be grown as needed) and the expected benefits. capable of being cultivated in many different environments. In addition they are an integral part of the • Fourth, the assessments must address the global and emerging ‘bio-economy’, where plant material is used to regional impacts, not just local ones. produce specific chemicals and bulk industrial chemicals. In the future these may increasingly replace chemicals A coherent biofuels policy must address and balance all derived from fossil oil. The full picture, however, is much these factors if biofuels are to make a sustainable more complex as different biofuels have widely differing contribution to reducing climate change and improving environmental, social and economic impacts. energy security. Biofuels are already entering the market, driven amongst Our study draws attention to the above caveats but does other things by their potential to improve energy security not go into detailed analysis. Nevertheless it is vital that and to contribute to climate change mitigation. While in other studies fully assess these issues because such certain conditions the best use of the plant material – information will give a more complete picture of the biomass – is to burn it to produce heat and electricity, extent to which biofuels are sustainable. We have focused biofuels are one of the few technologies currently available in this report primarily on the research and development that have the potential to displace oil and provide benefit that would be needed to improve the efficiency of to the transport system. There are real opportunities to biofuels. Our analysis suggests that there is considerable develop efficient biofuel supply chains that can deliver potential to improve the performance of biofuels. This substantial greenhouse gas savings. Biofuels on their own requires applying incentives for low carbon biofuels and cannot deliver a sustainable transport system and must be will also accelerate the development of a range of developed as part of an integrated package of measures, technologies across the biofuel supply chain to ensure that which promotes other low carbon options and energy more efficient technologies are brought into the market. a One barrel = 163.6 litres The Royal Society Sustainable biofuels | January 2008 |1 Feedstocks and conversion processes negate any of the intended future climate benefits, as well as having major impacts on conservation of Biofuels are currently produced from the products of biodiverse habitats. Switching already cultivated land to conventional food crops such as the starch, sugar and oil producing biofuel feedstocks could create shortages in feedstocks from crops that include wheat, maize, sugar the previously grown crops. Planting uncultivated land cane, palm oil and oilseed rape. Any major switch to could put pressure on such purposes as conservation of biofuels from such crops would create a direct biodiversity, and amenity use. Developments in the competition with their use for food and animal feed, and agricultural sector for food and non-food crops will have in some parts of the world we are already seeing the important implications for water usage and availability. economic consequences of such competition. The input of artificial fertiliser to increase yield must be carefully regulated or reduced to prevent emissions of Future biofuels are likely to be produced from a much nitrous oxide, a potent greenhouse gas, either directly broader range of feedstocks including the lignocellulose from the area of application or from drainage waters in dedicated energy crops, such as perennial grasses, and downstream. Such opportunity costs and side effects from forestry, the co-products from food production, and have to be fully factored into any decision to assign land domestic vegetable waste. Advances in the conversion to biofuel feedstocks. processes will almost certainly improve the efficiency and reduce the environmental impact of producing biofuels, The UK has 24.25 million hectaresb (Mha) of land, of from both existing food crops and from lignocellulose which 6 Mha is arable and 2.4 Mha forest.