Global and local impacts of UK renewable energy policy

Abstract

Energy policies within one country or region can have significant global impacts, with unforeseen consequences. As an example, the EU requirements for 20% of final energy to be derived from renewable sources by 2020 feeds in to a UK target for renewable energy to make up 15% of UK final energy demand by 2020; the implications of this are investigated and found to have global repercussions. In order to achieve the UK target it is essential that the existing strategies for delivering wind power and coupling it to the grid are successful but there is an additional, greater, challenge. A large part of the UK renewables target will need to be met by the use of biomass and we show here that the amounts of biomass needed far exceed the supply capacity of the UK; imports will dominate the supply. The imports required are far greater than present day UK imports of coal with substantial potential implications; globally for biomass markets with potential impact on food supply and deforestation, and locally for UK infrastructure in shipping, ports, rail, road freight, electricity transmission networks and the coal industry. The way that a single country's response to a regional energy strategy can have global implications are investigated using one reference scenario for future UK fuel needs as an example. A strong outcome is that to implement this level of rapid change in the energy supply chain whilst avoiding negative impacts in a rapidly expanding global market there is a need for synchronisation of policies across economies as a whole, including anticipated effects beyond national borders, rather than policy measures in separate, isolated areas such as energy.

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Broader context

Energy policies within one country or region can have significant global impacts, with unforeseen consequences. This paper examines the potential impacts using a specific example – the UK target for renewable energy supply in 2020. This local target, derived from a regional, EU, energy policy, has impacts on markets and infrastructure at the national, regional and global scale. In particular, the implications for UK biomass use are substantial, not only exceeding UK capability to produce biomass but exceeding the present day UK import of coal and indeed the present global trade in biomass-for-energy. The required transitions in global markets as well as in local infrastructure such as port capacity, domestic transport, location of industry and in the electricity supply network are described, as well as the potential for adverse consequences both locally and globally, particularly on the poor. This analysis points to a pressing need for synchronisation of policies across the economy as a whole, including assessment of overseas consequences, rather than in individual areas, such as energy, separately. This time we have to get the policy right straight away to ensure that energy policies do not trigger devastating effects elsewhere.

Introduction

Local decisions can have global impacts! This is a well-established concept, which made its way into policy analysis when the EU biofuels directive was suspected to have contributed to deforestation in South East Asia. In order to avoid these unintended policy consequences, it is of paramount importance to gauge the global impact of local policy prior to policy implementation. Following the imperfectly designed biofuels directive, the EU renewables target could lead to equally adverse global consequences unless negative impacts are assessed at the start and policies put in place to minimise them. Herein, we illustrate using the United Kingdom as an example of how a Western country's renewables targets can impact global issues.

The UK has a binding target to supply 15% of final energy demand from renewable sources by 2020; a target derived from the EU commitment to obtain 20% of final energy from renewables. This is in addition to targets for improving energy efficiency and reducing carbon emissions as well as the wider energy issues such as the role of nuclear power in the future UK energy mix. Whilst these are very challenging targets, it is not the purpose of this assessment to state the difficulty of achieving the renewables target, but rather to assess approaches to reaching this target, and to determine the implications, both for global markets and the wider UK economy and infrastructure.

In the UK energy policy, the implementation of renewable energy technologies is treated separately from the policy to reduce carbon emissions, although there is obvious overlap. We will follow this approach here, assessing the renewable policy rather than its carbon implications, in particular because the emission reduction potential of biomass still involves a significant amount of uncertainty with different outcomes for different technologies and sources of biomass. Opponents of widespread biomass use argue that the estimated reductions of carbon emissions are spurious¹ whilst proponents see biomass for energy as a route to emissions reduction as well as a means to spur development in rural communities. The intention of this study is to explore the amounts of biomass for energy necessary to meet the UK renewables targets and to assess the impact on local and global infrastructure and trade; we leave the precise discussion of the associated emission reduction potential, and how to maximise it, to the expert community. The context of this ongoing debate is summarised in the Global Forest Resource Assessment from the UN FAO: “While sustainable management, planting and rehabilitation of forests can conserve or increase forest carbon stocks, deforestation, degradation and poor forest management reduce them”.²

At present, UK final energy demand is equivalent to a continuous power consumption of 210 GW, or 3.5 kW per person.³ The 2020 target translates to an equivalent of 32 GW of continuous power, to be supplied by a mix of renewable sources. For comparison, the present (2010) total use of renewable energy in the UK corresponds to 6.9 GW with approximately half of this in the electricity market and a quarter in each of the heat and transport biofuels sectors. The 2020 target corresponds to increasing this by a factor of around 5 in 9 years, an increase of 20% per year. This rate of growth has been achieved and even exceeded in the past, for instance by nuclear power globally in the 1970's, but we must determine how best it can be done, what measures need to be in place to allow it to happen and what, if any, are the consequences for global energy supply and markets.

The present UK production of renewable energy is primarily from biomass and wind, contrasting with the pattern in most renewable intensive countries where biomass and hydroelectricity dominate. Approximately half of the present renewable UK electricity and essentially all of the heat and transport fuels come from biomass, with landfill gas currently the biggest contributor. Altogether, biomass makes up around 75% of today's renewable energy production in the UK and is expected to continue to play a major role in future renewable energy supply, with substantial implications for UK infrastructure.

Achieving the UK target

There has been substantial work on the best approach to achieving the 2020 target (e.g.ref. 4 and 5) so this will not be repeated here, however, as we will see below, the role of solar and marine energy in achieving the 2020 targets is expected to be low. By way of support for such assessments it is noted here that installation of Photovoltaic systems on 20 million UK domestic roofs would require a very large increase in installations but only contribute approximately 2% to UK final energy demand (assuming 2 kW installations with 10% load factor would yield an average power of 4 GW compared to 210 GW final energy demand)⁵ – it seems implausible that such systems will make a significant contribution by 2020. A similar consideration applies to tidal power – on the timescale of 2020 it is very unlikely to contribute at the scale required, particularly given that the largest proposal, the Severn barrage, would only supply 1% of present UK final energy demand (with 8 GW peak and a 25% load factor, the average power is 2 GW compared to 210 GW total demand). Whilst in the longer term these other renewables, particularly solar, may make a substantial contribution, the overall outcome of assessments out to 2020, that the targets are most likely to be met by large scale implementation of wind power, for electricity, and biomass, for electricity, heat and transport fuels, seems plausible.⁶ What are the implications?

The outcome of renewable policy is uncertain but to serve as a concrete example we will base what follows on existing UK use of renewables³ and on the DECC 2011 analysis of how this may evolve.⁵ In this analysis we can broadly divide UK renewable energy supply out to 2020 into 6 main categories: onshore wind electricity; offshore wind electricity; biomass electricity (including co-firing or converting coal plant to burn biomass); biomass for heat; biofuels, and all other renewables (mostly heat pumps, but also solar, marine, etc.). In the DECC scenario assessment to 2020, the outcome is that these categories will be broadly comparable, at an equivalent final power supply of approximately 4–6 GW each (Fig. 1).⁵ We must ask how this can be achieved, what the implications for the wider economy, including infrastructure renewal, are, and how undesirable outcomes can be minimised.

Firstly, as we will see below, the challenge for large biomass production is so great that we must deliver on the wind production if we are to meet the 2020 targets.⁶ It seems essential to install sufficient new turbines to exceed 20 GW (and approach 30 GW) of wind capacity by 2020 if the target is to be achieved. We will here assume that this is achievable, and the necessary policies to deliver this will be in place, recognising of course the challenge that this presents, not least during times of austerity.

In determining the biomass feedstock requirements we must take into account that the efficiency of production of final energy varies across energy products. The efficiency of production of electricity from biomass is presently around 27% (an average value including dry biomass and wastes), whereas the efficiency of supply of heat is likely to be 80% or higher. Liquid fuels manufactured from biomass are a special and controversial case; some biofuels consume more energy than the fuel combustion provides^7–10 and, moreover, emissions from land-use change add to the overall carbon balance of the fuel.^11–13 It is essential that sustainability criteria are defined and rigorously enforced during the expansion of the global market, for instance only to use biofuels with a clear positive environmental impact. Here we will assume an optimistic scenario and base our calculations on an average efficiency for biofuels production of 50%. If we are to achieve 5.5 GW average power in each of these 3 areas, then a primary energy from biomass of around 37 GW will be needed. With an average energy content of plant-based biomass of 15 MJ kg⁻¹, this level of biomass energy supply will require approximately 80 million tonnes of biomass per year, more than 1 tonne per person in the UK. This is a large number but is not too surprising when compared to UK annual oil consumption of 80 million tonnes, particularly given that a tonne of oil contains around 3 times more energy than a tonne of wood. Large supplies of energy require large quantities of fuel.

Indigenous biomass supply

The opportunities for domestic supply of biomass in the UK are very limited, on the scale that we are discussing, even though present biomass supply is quite diverse (including landfill gas for instance).^14,15 The total UK annual production of wood is approximately 10 million tonnes,¹⁶ whilst the total agricultural production of arable crops is around 30 million tonnes.¹⁷ In this context, the production of up to 80 million tonnes of plant-based biomass from domestic sources is highly implausible as it would require the diversion of substantial land area from food production to biomass production^11,18 (approximately all of the present UK arable land would be required). It appears that the majority of this biomass will have to be imported, in much the same way that the majority of our coal is imported today. As a comparison, however, present coal imports are approximately 30 million tonnes, so biomass imports are expected to be higher than present coal imports, again unsurprising if we are to get a substantial fraction of our energy from biomass.

We recognise that this is a simplification of the real UK biomass market, in which the largest indigenous supply is currently from waste sources, particularly landfill gas. Assessments of the future supply of indigenous biomass^14,15 include the possibility that up to 30% of UK biomass supply in 2020 could come from indigenous sources. Even if this optimistic target were achieved, the qualitative challenge of large biomass imports remains; it does, however, indicate the level of uncertainty in future predictions.

Global impacts – global biomass market and sustainability

While the use of biomass as an energy resource has the potential to contribute to renewable energy supply, policies supporting this have to be set out with tremendous care in order to minimise the risk of adverse effects. The most prominent example of adverse effects relates to the EU biofuels directive (2003/30/EC) that aimed at replacing 5.75% of all fossil transport fuels with biofuels. Since it was impossible to produce such copious amounts of biofuels domestically,† the EU relied on imports and hence created an additional market for biofuels. This market, along with changing demand for edible oils, has contributed to land-use change in the developing world e.g. deforestation in South-East Asia for palm oil farming.⁸ Hence, the emissions reduced from transport in the EU were more than offset by emissions caused by deforestation. The EU directive therefore increased emissions on a global scale and moreover counteracted the UN initiative on Reducing Emissions from Deforestation and Degradation (REDD)¹⁹ an example where lack of coherence across policy areas can lead to contradictions.

Fig. 1 The projected potential for different sources of renewable energy to contribute to the 2020 targets; including a range of possible outcomes. The category labeled “other” is primarily energy from heat pumps but also includes solar and marine energy. Data taken from ref. 5.

It is therefore critical that the biomass utilised to fulfil the UK renewables target, and similar requirements from other biomass-poor nations, is produced sustainably.²⁰ We herein analyse global biomass availability and trade in order to gauge whether the target can be readily met without adverse policy effects. In Fig. 2 the global total forestry production is compared to direct global trade in biomass for energy and the requirements derived here to meet the UK renewables targets. From this comparison it can be seen that the UK import requirement is 4% of global forestry production^21,22 and hence such a policy, particularly if replicated across other industrialised countries, may have a direct impact on forestry, not least in the least-developed countries. Poor and very poor‡ rely on biomass as an energy source and, in part because of its inefficient use, could easily be priced out of the market by increasing demand from industrial countries. Here, policies have to be designed to ensure that local and regional markets in the developing world are not affected while simultaneously providing development opportunities.

Fig. 2 Although the potential UK 2020 needs for imported biomass are small compared to the world forestry production, they are large compared to the present day international direct trade of biomass for energy. With other countries also expected to demand increased biomass for energy, there is a need for a dramatic increase in globally traded biomass.^21,22

One possible way to circumvent such adverse effects is to restrict biomass imports to sources from sustainable forestry in developed countries such as Scandinavia and Canada and simultaneously aid developing countries in establishing sustainable biomass production; however we refer again to the ongoing debate around emissions reduction and sustainability in biomass production and use.²³ The interested reader is referred to the recent and extensive literature around forestry biomass and its inherent emissions.^24–28

Fig. 2 highlights a further issue that has to be addressed: comparing current global biomass trade to the import requirements shows the amount of biomass expected to be transported to the UK is six times higher than present global trade, this too is an issue with multiple implications where national and international transport policy has to be aligned with national energy policies. Moreover, in case other countries were to follow the British lead the impact on global biomass production and trade would be even more severe and the global biomass market would be significantly distorted. If the world population consumed biomass for energy at the rate of 1 tonne per person per year implied by the UK energy targets, the total demand would exceed the present global forestry production by a factor of approximately 3 whilst providing approximately 20% of present world energy demand.

Overall, it is clear that there is both the need for, and scope for a very large increase in global trade of biomass for energy, if targets for renewable energy production are to be realised. As this growth proceeds, it is essential that potential negative impacts are identified, monitored and minimised.

Local impacts

UK infrastructure

The usual discussion of renewable energy and transport centres on the use of biofuels, particularly their lifecycle carbon emissions. However here we will explore the requirements for transport of biomass (rather than transport by biofuels) adopting the 80 million tonnes figure outlined above. We will quickly see that the import and distribution of this mass of material has significant implications.

On arrival in the UK, we need to ensure that the port capacity is in place. The total capacity of UK ports – for all imports – is around 500 million tonnes per year, of which around 7% is presently coal. Adding 80 million tonnes of biomass to this may be possible but is substantially greater than present coal imports and would need to be included in strategies and policies as it represents a significant growth. It is not clear that the scale of this is recognised – the UK Renewable Energy Roadmap³ talks of Tilbury being an import hub for biomass, with a capacity to import 4 million tonnes – this will not make a substantial contribution to the required biomass imports. The required port capacity may be available but it may also provide a bottle neck to achieving the 2020 targets without incentives.

Having imported biomass, either the fuel or its product needs to be distributed appropriately. This may be challenging because of the large quantities involved with between 2 and 3 times the weight, and closer to 5 times the volume, of present coal imports. An example of the implications for freight arises from a comparison with present UK rail freight. At around 100 million tonnes per year,²⁹ present total UK rail freight is not much larger than the potential import requirements for biomass, and would have to be substantially increased if a significant fraction of the imported biomass were to be transported by rail. Again, whilst this does not seem impossible, it should be already included in strategic policies and it is far from clear that this rationalisation of policies across sectors, particularly energy and transport, is happening. Fig. 3 shows an illustrative scenario for the development of UK rail freight capacity if the imported biomass is transported by rail.²⁹ As things stand, transport by road is likely to be the default option with associated implications for congestion, pollution, oil demand and accidents.

Fig. 3 Illustrative effect of biomass transport on projected rail freight, assuming that the majority of the biomass would be transported by rail from ports to electricity, heat and biofuels plants. Source (for non-biomass data and projections): Network Rail.²⁹

It would clearly be advantageous to mitigate some of the need for increase in freight, particularly given the short timescale involved. The optimum approach to this is different for each of the main categories: electricity; heat, and biofuels. In electricity, it may be advisable to generate biomass-fired electricity near the point of import, to avoid large internal transport of biomass; on the other hand it is not always convenient to generate electricity at or near ports and also has major implications for the electricity transmission system – even though the financial cost of new overhead power lines may be acceptable, the planning issues are likely to be very complex. If large freight increase is to be avoided, there are large implications for power sector infrastructure, particularly for the location of power stations and high voltage transmission lines.

With biofuels production, freight requirements could be reduced by importing the biofuel products directly, which would have the added benefit of reducing the overall import of biomass, or by locating production facilities near ports, then distributing by pipeline. The facilities may be located near existing refineries and the product blended into oil-based transport fuels directly, which seems a logical way forward, as long as the planning is in place for these large imports or biomass production facilities. It seems likely that importing large quantities of biofuels will be achievable. It is well known that there are ethical and environmental concerns around the import of biofuels; present biofuels production has been blamed for deforestation and for competing with food supply in the countries of origin. These are complex issues, for instance food security is affected by much more than just land availability. These are examples of the undesirable outcomes which need to be minimised and the UK 2020 targets should not take precedence over these concerns. Again, definition of sustainability criteria and enforcing good practise during the expansion of markets will be crucial.

In using biomass for heat, large transport requirements could be avoided by locating industrial users near ports, however this is likely to require relocation of substantial industrial capacity presenting challenges to planning, labour distribution and capital utilisation. Again, this will contribute to substantial perturbation of UK infrastructure.

Displacement of existing fuels

In giving the amount of biomass that needs to be imported and transported, it has been implied that this is in addition to present import of fuels.³⁰ This is an overestimate of the difficulty, of course, because the introduction of renewables will reduce the consumption of existing fuels – this is one of the objectives underlying the renewables targets. The proposed wind generated electricity, if it were to replace coal-fired production for example, would displace 18 Mtonnes of coal imports. Similarly, the import of biomass would displace significant amounts of coal and other fuels. Whilst it depends on which fuels are displaced, an estimate of the size of avoided imports makes it comparable to total UK coal import. This question of what fuel can be displaced is absolutely crucial in determining the infrastructure implications and scenario modelling should be carried out to inform the future policy on infrastructure renewal to meet the 2020 targets. The implications are entirely different, for instance, if gas is displaced rather than coal, since gas pipelines cannot be used to distribute solid biomass feedstocks.

The outcome for fuel imports in 2020 depends on assumptions, of course, so we cannot predict with confidence the expected changes; however we can give an outcome on the basis of a set of reasonable assumptions. In what follows the key assumptions made are: biofuels are used in the transport sector and displace oil; biomass used for heating is primarily in the industrial sector and displaces gas; renewable electricity displaces coal, primarily as a result of the additional policy driver of reducing CO₂, but goes beyond that to displace some gas as well. These key guiding assumptions are sufficient to produce one plausible outcome of the 2020 renewable targets.

Fig. 4 shows the result of a 2020 energy analysis for UK final energy demand, in which coal consumption is preferentially reduced, for reasons of carbon reduction, in satisfying the 2020 targets – total final energy demand is reduced slightly here on the basis that economic growth will be cancelled by improved energy efficiency leading to a reduced energy intensity. Whilst the total fuel consumption is increased by only 16% in this analysis, the import of solid fuel (assuming all of the biomass is imported in solid form) is increased by 170% by weight, and around 370% by volume. This is expected to present a significant challenge to shipping, handling in ports and transport within the UK. There is the additional challenge of completely restructuring the UK coal industry between now and 2020. It also challenges the view that coal with carbon capture and storage will play an important role in low carbon UK energy supply since in this scenario, coal will have been completely displaced from the electricity sector by 2020.

Fig. 4 One scenario for change in UK fuel consumption as a result of the 2020 renewables targets. The projected reduction of fossil fuels, with coal preferentially reduced, is due to the combined effect of all renewables in the energy market. In spite of the reduced demand for fossil fuels the overall consumption of fuels is expected to increase. In terms of solid fuels, these are expected to increase very substantially with a switch from coal to biomass. Only plant based biomass is included here; contributions from waste are not included as it is assumed in this example scenario that the large growth in biomass will not be in this category – pressure to make increased use of waste will be significantly counteracted by pressures to reduce waste.

Conclusions

Regional and local energy policies can have substantial effects on energy and other markets even beyond the countries directly concerned. The example is given here of the UK 2020 renewable energy target and how that is expected to impact on global and regional markets, infrastructure and energy supply.

A strong implication of the UK energy targets, and the assessment of how they can be plausibly met, is that there will have to be a large consumption of biomass for electricity, heating and transport use. Given the large land area that this will require (larger than present total UK arable land) this can only be achieved by the import of large amounts of biomass; this import will be very large compared to present day import of coal with quantities several times larger (by weight, even greater by volume) than present day import of coal.

The global implications of this local energy policy are substantial – the biomass demands of the UK alone are expected to be very much greater than the present total international trade in biomass for energy. In addition, there are ethical and environmental concerns about the large import of biomass. Biofuels production has already been associated with deforestation and competition with food production and it is essential that sustainability criteria are defined and enforced in this expansion of the global market to avoid substantial negative consequences. The analysis here focussed on growth of biomass demand in a single country, the UK; if other countries and regions follow a similar track, the pressure on production and trade of both biomass and food will be very great. In addition to potential impact on food production and deforestation around the world, a negative consequence may be higher biomass prices with associated impact on the availability of biomass for the poor globally.

In terms of local impacts, the UK is expected to require a significant increase in fuel imports, with the reduction in imports of fossil fuels more than offset by the increase in import of biomass. The import and use of this amount of biomass represents a significant, but probably achievable, increase in UK port capacity and has large potential implications for rail and road freight, electricity transmission infrastructure and location of industry. It is not clear that the infrastructure upgrades required to handle this fuel import and use will be delivered on the necessary timescale. Synchronisation between policies in different areas, particularly energy and transport is essential, both within the UK and internationally.

In analysing in more detail the wider energy scenario for the UK, the 2020 renewables targets present a large challenge both to the UK coal industry and to the policy of promoting coal with carbon capture and storage as a future energy option. The socio-economic impacts of switching out of coal as a fuel altogether should not be underestimated, nor should the impact of the inferences drawn here from one energy policy – the renewables target – impacting on another – the CCS ambitions. The renewables targets imply the removal of coal from the UK energy supply chain hence the development of coal with CCS technology becomes redundant, at least on the timescale considered. Whilst we recognise that this analysis is based on an exploration of only one future scenario, it is consistent with the DECC renewable energy roadmap. Given the enormous impacts implied by this view of the future, it is crucial that additional work is urgently done to further explore options, possibly identifying an alternative roadmap for renewable energy, and rationalise policies across a wider range of areas.

In summary, the impacts of energy policy in one country on global markets can be substantial. The 2020 renewables targets for the UK imply a need for a large increase in international trade in biomass and correspondingly in international transport of fuels. The optimum way to source, distribute and utilise this biomass is not clear but in all cases it appears that there are strong interactions between energy policy, transport, food production and forestry globally and these different policy areas need to be addressed as an integrated system rather than individually. There are, in addition, strong local impacts, within the UK, particularly related to both energy and transport infrastructure and location of industrial consumers. Again, there is a pressing need for synchronisation of policies across the economy as a whole rather than in individual areas separately.

On a global scale, it has to be ensured that ambitious renewables targets in Western countries are met in a sustainable way which does not negatively impact the poorest worldwide. An increased demand for biomass energy is likely to affect prices of biomass and could potentially price out of this market those who rely on biomass as their only energy source. This time we have to get the policy right straight away to ensure that energy policies do not trigger devastating effects elsewhere.

References

1. T. Searchinger, Global Consequences of the Bioenergy Greenhouse Gas Accounting Error, in Energy, Transport & the Environment, ed. O. R. Inderwildi and D. A. King, Springer, Berlin London New York, 2012, ISBN 978-1-4471-2717-8.
2. Food and Agriculture Organisation of the United Nations, Global Forest Resources Assessment 2010, Forestry Paper 163, Rome Italy, 2010.
3. DECC, Digest of United Kingdom Energy Statistics 2012, London, UK, 2012, http://www.decc.gov.uk/assets/decc/11/stats/publications/dukes/5949-dukes-2012-exc-cover.pdf.
4. C. Mitchell, D. Bauknecht and P. M. Connor, Effectiveness through risk reduction: a comparison of the renewable obligation in England and Wales and the feed-in system in Germany, Energy Policy, 2006, 34(3), 297–305.
5. DECC, UK Renewable Energy Roadmap, London, UK, 2011, http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/renewable-energy/2167-uk-renewable-energy-roadmap.pdf.
6. D. A. King, G. Butler, M. E. Evans, O. R. Inderwildi, G. McGlynn and R. Flood, Towards a Low Carbon Pathway for the UK, University of Oxford, UK, 2012.
7. O. R. Inderwildi and D. A. King, Quo vadis biofuels?, Energy Environ. Sci., 2009, 2, 343–346.
8. X. Y. Yan, O. R. Inderwildi and D. A. King, Biofuels and synthetic fuels in the US and China: a review of well-to-wheel energy use and greenhouse gas emissions with the impact of land-use change, Energy Environ. Sci., 2010, 3(2), 190–197.
9. T. Shirvani, X. Y. Yan, O. R. Inderwildi, P. P. Edwards and D. A. King, Life cycle energy and greenhouse gas analysis for algae-derived biodiesel, Energy Environ. Sci., 2011, 4(10), 3773–3778.
10. X. Y. Yan, D. K. Y. Tan, O. R. Inderwildi, J. A. C. Smith and D. A. King, Life cycle energy and greenhouse gas analysis for agave-derived bioethanol, Energy Environ. Sci., 2011, 4(9), 3110–3121.
11. T. D. Searchinger, S. P. Hamburg, J. Melillo, W. Chameides, P. Havlik, D. M. Kammen, G. E. Likens, R. N. Lubowski, M. Obersteiner, M. Oppenheimer, G. P. Robertson, W. H. Schlesinger and G. D. Tilman, Fixing a critical climate accounting error, Science, 2009, 326(5952), 527–528.
12. T. Searchinger, The Impacts of Biofuels on Greenhouse Gases: How Land Use Change Alters the Equation, Policy Brief, The German Marshall Fund of the United States, Washington D.C, 2008.
13. D. Tilman, R. Socolow, J. A. Foley, J. Hill, E. Larson, L. Lynd, S. Pacala, J. Reilly, T. Searchinger, C. Somerville and R. Williams, Beneficial biofuels-the food, energy, and environment trilemma, Science, 2009, 325(5938), 270–271.
14. DECC (Commissioned to AEA), UK and Global Bioenergy Resource, Didcot, UK, 2011.
15. Committee on Climate Change and House of Lords, Bioenergy Review, London, UK, 2011, http://downloads.theccc.org.uk.s3.amazonaws.com/Bioenergy/1463%20CCC_Bioenergy%20review_interactive.pdf.
16. Forestry Commission, UK Wood Production and Trade (provisional figures), London, UK, 2011, http://www.forestry.gov.uk/pdf/trprod11.pdf/$file/trprod11.pdf.
17. H.M. Government, National Statistics, 2012, http://data.gov.uk/dataset/annual_abstract_of_statistics.
18. J. Fargione, J. Hill, D. Tilman, S. Polasky and P. Hawthorne, Land clearing and the biofuel carbon debt, Science, 2008, 319(5867), 1235–1238.
19. FAO, UNDP and UNEP, Reducing Emissions from Deforestation and Forest Degradation in Developing Countries, 2008, http://www.un-redd.org/Portals/15/documents/publications/UN-REDD_FrameworkDocument.pdf.
20. IPCC, IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation. Prepared by Working Group III of the Intergovernmental Panel on Climate Change, ed. O. Edenhofer, R. Pichs-Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. Schlömer and C. von Stechow, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2011.
21. J. Heinimo, Methodological aspects on international biofuels trade: international streams and trade of solid and liquid biofuels in Finland, Biomass Bioenergy, 2008, 32(8), 702–716.
22. J. Heinimo and M. Junginger, Production and trading of biomass for energy – an overview of the global status, Biomass Bioenergy, 2009, 33(9), 1310–1320.
23. P. Bernier and D. Pare, Using ecosystem CO₂ measurements to estimate the timing and magnitude of greenhouse gas mitigation potential of forest bioenergy, GCB Bioenergy, 2012 DOI:10.1111/j.1757-1707.2012.01197.x.
24. B. Holtsmark, Harvesting in boreal forests and the biofuel carbon dept, Clim. Change, 2011, 112, 415–428.
25. T. W. Hudiburg, B. E. Law, Ch. With and S. Luysseart, Regional carbon dioxide implications of forest bioenergy production, Nat. Clim. Change, 2011, 1, 419–423.
26. J. Mckechnie, S. Colombo, J. Chen, W. Mabee and H. Maclean, Forest bioenergy or forest carbon? Assessing trade-offs in greenhouse gas mitigation with wood-based fuels, Environ. Sci. Technol., 2011, 45, 789–795.
27. S. R. Mitchell, M. E. Harmon and K. B. O'Connell, Carbon debt and carbon sequestration parity in forest bioenergy production, GCB Bioenergy, 2012, 4, 818.
28. G. A. Zanchi, N. Pena and N. Bird, Is woody biomass carbon neutral? A comparative assessment of emissions from consumption of woody bioenergy and fossil fuel, GCB Bioenergy, 2011, 4, 761.
29. Network Rail, Value and Importance of Rail Freight, London, UK, 2010, http://www.networkrail.co.uk/9083_ValueofFreight.pdf.
30. International Energy Agency, Bioenergy Project Development and Biomass Supply, Paris, France, 2007, http://www.iea.org/textbase/nppdf/free/2007/biomass.pdf.

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Footnotes

† Within the European Union.

‡ According to a norm published by the World Bank, the poor live on less than $2 a day, while the very-poor have to struggle with less than $1 per day.

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