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Climate change and energy policy: The importance of sustainability arguments
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Energy 32 (2007) 262–268 www.elsevier.com/locate/energy
Keynote Paper
Climate change and energy policy: The importance of sustainability arguments Roland Clift Centre for Environmental Strategy, University of Surrey, Guildford, Surrey GU2 7XH, UK Received 1 November 2005
Abstract It is the stated policy of the UK government to reduce emissions of carbon dioxide by 60% by 2050. This policy, which goes far beyond commitments under the Kyoto agreement, was originally advocated by the Royal Commission on Environmental Pollution, of which the author was a member. Its acceptance was seen by many as a surprising development, possibly reflecting the strength of the underlying case. The target was developed by a three-legged argument which reflects the three components of sustainability: Environmental constraints: limits on emissions to avoid risk of major climate change; Social equity: equal per-capita allocation of emissions; Techno-economic: the feasibility and cost of reduction on this scale. Assessment of techno-economic feasibility shows that the target can be achieved economically if the efficiency of energy use is improved to achieve reduction in demand, combined with a shift to lower-carbon energy sources. The greatest scope for demand reduction lies in improving the building stock, combined with providing low-grade heat from sources such as biomass. On the supply side, the principle questions are how much controllable electricity generation is needed, and whether this capacity should be nuclear or fired by fossil fuels with the carbon dioxide formed sequestered in geological strata. Increased use of biomass is a key part of the shift to a lower carbon economy; the barriers which have retarded the development of biomass in the UK are explored. r 2006 Elsevier Ltd. All rights reserved. Keywords: Energy policy; Climate change; Energy scenario
1. Introduction The author was, until 2005, a member of the Royal Commission on Environmental Pollution (RCEP), a uniquely UK institution appointed 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. The RCEP has been in continuous existence but with rotating membership since 1970. It is constituted as a body of independent experts, standing outside the political mainstream but intended to provide advice to guide long-term environmental policy. An important role for the RCEP is to present scientific evidence and its implications which may be obvious to the scientific community but politically Corresponding author. Tel.: +44 1483 689271; fax: +44 1483 686671.
E-mail address: [email protected]. 0360-5442/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2006.07.031
inconvenient. Some of the RCEP’s reports have had a significance which extends outside the UK; for example, the concepts of Integrated Pollution Control and Best Practicable Environmental Option originated with the RCEP. In a report published in 2000 [1], the Royal Commission addressed the issue of climate change and its relationship to energy supply. The principal recommendation of the RCEP’s analysis was that carbon dioxide emissions from human activities in the UK must be reduced by 60% below 1998 levels by 2050. The year 2050 was itself chosen carefully: even the most enthusiastic advocates of nuclear fusion did not consider that it would be available before 2050, so that the target would have to be met by known energy technologies.1 At the time, this target appeared to 1 RCEP also recommended a decrease of 80% by 2100, but this longerterm target is not discussed in this paper.
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be too radical to be politically acceptable; for example, it goes way beyond negotiations under the Kyoto protocol. However, it was accepted, is now UK Government policy and progress towards the target is currently under review. The present paper reviews the argument which supported its acceptance and some of the implications of this policy. 2. The context: sustainable development The concept of sustainable development is now sufficiently well known that it will not be rehearsed here. However, a particular interpretation of sustainable development which has proved useful in teaching the concept to engineers and scientists [2] will be reviewed, because it illustrates and supports the argument developed by the RCEP [1]. The basic idea is that human activities are limited by three sets of long-term constraints, summarised by the Venn diagram in Fig. 1. Eco-centric concerns represent the constraints imposed by the fact that the earth is, in thermodynamic terms, a closed system. Thus, energy flux is received from the sun, but the ‘‘capital’’ resources available to us on a global scale are finite, as is the capacity of the biosphere to absorb or adapt to the emissions from human activities. Techno-centric concerns represent the constraints imposed by finite human abilities: the technology which we are able to deploy and the economic system within which we deploy that technology. This lobe represents the traditional scope of engineering. Socio-centric concerns represent human expectations: the need to provide a better quality of life for everyone, now and in the future (to quote from the UK Government’s interpretation of sustainable development). This lobe incorporates the principles of inter- and intra-generational equity which are central to the concept of sustainable development. Sustainable development involves moving towards complying with all three sets of constraints, not of trading off one set of objectives against another. Sustainability is to be found in the central area of Fig. 1, which meets all the sets of constraints, while
Natural resources and ecological capacity
TECHNO-CENTRIC CONCERNS
sustainable development is a process of moving towards that region. While it is recognised that Fig. 1 is a simplistic representation of a very rich concept, it has nevertheless proved to be useful as an educational device. Although not stated explicitly in the RCEP report, it is implicit that future use of fossil hydrocarbons will be constrained not by their availability but by the capacity of the biosphere to adapt to the emissions resulting from their use, specifically carbon dioxide. In other words, we already know the whereabouts of more fossil fuels than can be burned without risking disastrous climatic impacts; hydrocarbons in particular will continue to be available, albeit at prices well above historical levels (and possibly above current levels). To support this argument, current crude oil prices make it not only economic but very profitable to exploit oil sands; the quantity of ‘‘synthetic crude’’ available in Alberta is of the same order as the oil reserves in Saudi Arabia—a simple fact which is sometimes overlooked in discussions over the extent of remaining oil reserves. The driver for change in energy technology is therefore the effect of the emissions, not limited supply; as Sheikh Yamani famously put it, ‘‘The stone age did not end because we ran out of stones’’. While the conventional market system can deal with scarcity of supply through rising prices which make new reserves economic, it is necessary to invent a new mechanism to deal with scarcity of ‘‘carrying capacity’’ to absorb emissions. It remains to be seen whether emission trading systems like that being introduced in Europe will constitute an effective market, whether the price will be sufficiently high to influence energy use and whether carbon prices will be sufficiently stable for effective long-term planning and restructuring of the energy system. The Royal Commission sidestepped the continuing arguments over whether the effects of carbon dioxide emissions, can be represented in terms of a simple economic damage cost (or ‘‘externality’’) by addressing energy policy and climate change in a different way using the approach, introduced above, of recognising and trying to estimate the constraints. 3. Policy recommendations
ECO-CENTRIC CONCERNS
Techno-economic systems
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Human capital and social expectations SOCIO-CENTRIC CONCERNS
Fig. 1. Sustainability expressed as long-term constraints [2].
The Royal Commission’s report starts with an analysis of the evidence that emissions of climate-forcing ‘‘greenhouse gases’’ from human activities are causing changes in the global climate and regional weather patterns. In effect, it endorsed the conclusions of the UN Intergovernmental Panel on Climate change (IPCC). To quote the RCEP report [1], the world is now faced with a radical challenge of a totally new kind which requires an urgent responsey By the time the effects of human activities on the global climate are clear and unambiguous it would be too late to take preventive measures. This statement may not be news to the scientific community in Europe, but was necessary at the time of publication (2000) to underpin the Commission’s recommendations; although the UK government now
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stresses its belief that climate change represents a real and serious threat, this commitment has emerged since publication of the RCEP report. Of more interest here is the analysis which followed, which had three principal steps: 1. If the concentration of carbon dioxide in the atmosphere gets too high, then there will be a risk of really catastrophic climate change associated, for example, with changes in ocean circulation patterns. RCEP proposed 550 ppm as the ceiling, a constraint which must not be breached. Some would prefer a lower limit—at 550 ppm, the predicted rise in sea level is still bad news for low lying Pacific islands, for example—and information on the effects of climate change which has become available since 2000 arguably supports a lower figure. However, 550 ppm already represents a major departure from ‘‘business as usual’’ [3] and there was also a measure of political realism behind the figure (see below). 2. Working back from the 550 ppm constraint, RCEP estimated the total tolerable CO2 emissions, and then divided them by total global population to get the per capita ration. Multiplying by the population of the UK gave about 40% of current emissions—hence the recommended target of a 60% reduction below 1998 levels. This is known as the ‘‘contract-and-converge’’ principle. It simply ignores economists’ attempts to calculate an optimal level of CO2 emissions, on the basis that the damage cost or ‘‘externality’’ figures mean little when the climatic system is so complex and non-linear (and therefore chaotic) that detailed predictions of climate change and its effects, as distinct from estimating thresholds or constraints, are meaningless. 3. To explore the practicality of the 60% reduction target, RCEP developed representative scenarios to illustrate how it might be achieved (see below). Based on these scenarios, the cost of shifting to a low-carbon energy economy was subsequently estimated as about 2% of annual GDP. The cost is sometimes described as ‘‘enormous’’ but, as an economist will always ask, compared to what? The economists who produced these estimates also project 4% annual growth in GDP. So taking action to limit the potentially catastrophic effects of global climate change would merely slow down the rise in consumer spending in developed countries. Given that most forms of consumer spending in industrialised countries lead to carbon dioxide emissions, there is an argument that this in itself could have some effect in constraining the growth of climate-forcing emissions. It is interesting that, although not explicitly formulated in terms of the approach to sustainability summarised in Fig. 1, the three steps in the argument map exactly onto the three sets of constraints: ecological, societal and technoeconomic. Perhaps this illustrates the strength of this approach to sustainability analysis. To quote the RCEP
report again [1], y the UK could cut its carbon dioxide emissions by 60% by 2050. Achieving this will require vision, leadership, and action which begins now. Acceptance of the target of 60% reduction by 2050 has, so far at least, survived subsequent discussions over commitments under the Kyoto process and softening of UK government targets for shorter term reductions. In fact, the UK government has been advocating international acceptance of the 2050 target, and the Swedish government has also adopted it as a basis for energy policy.
4. Energy scenarios In order to explore the implications of a 60% reduction in carbon dioxide emissions, the RCEP constructed four scenarios to illustrate measures by which it might be achieved. These scenarios are only illustrations, not intended to be interpreted as predictions or projections, but they enabled rough estimates of the cost of the change (see above). Scenarios 1 and 4 were deliberately selected as extremes—respectively, ‘‘techno-fix’’ and ‘‘ecological living’’ —with scenarios 2 and 3 intended to represent more realistic energy futures. They had a number of common features. They were based on known technologies, assuming that electrical generation by nuclear fusion is not available by 2050 (see above). They took as their starting point the 1998 pattern of energy use in the UK, summarised in Table 1. Fig. 2 shows energy use updated to 2003, while Fig. 3 shows how UK carbon dioxide emissions have changed since 1990. Compared to continental European countries at comparable latitudes, domestic energy use is high because of the relatively poor energy performance of the UK building stock and the almost complete absence of heating systems distributing ‘‘low-grade’’ heat; the principal fuels for space and water heating are natural gas and electrical resistive heating.2 For obvious geographical reasons, the electricity grid in the UK is separate from that of continental Europe (apart from limited imports via a cross-channel link from France). Most of the decline in carbon dioxide emissions since 1990 is attributable to replacement of coal by natural gas in electricity generation (Fig. 3) although coal use has risen again since 1999. However, the proportion of renewable sources in the UK electricity system is still low by European Standards: only just over 1% of total inland energy use even in 2004. These features of the UK energy sector present possible savings in carbon intensity which are not available in other European countries, and which 2 Off-peak ‘‘night storage’’ heating is still used in the UK. It has been argued, principally by advocates of nuclear power, that this is to be encouraged, on the basis that future energy systems will be dominated by low-carbon fixed-output electricity generation. RCEP did not subscribe to this view, rejecting its implication that new buildings should be equipped with electrical heating to fit hypothetical energy system which might possibly exist at some future date. A subsequent study by the House of Lords [4] endorsed this conclusion.
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Table 1 Final energy consumption in 2050 by end-use (annual averages in GW) [1]
Table 2 Outputs from energy sources in 2050 (annual averages in GW) [1]
End-use category
Source
Scenario
High-grade heat Electricity Low-grade heat Transport Total
1 (as 1998)
2
3
4
87 32 16 70 205
44 24 12 53 132
44 24 12 53 132
30 21 11 47 109
12.3%
Transport
21.9%
Domestic Industry Services (including agriculture) 30.1%
Scenario 1
Intermittent renewables On-shore wind Off-shore wind Photovoltaic Wave Tidal stream Tidal barrage Total Other renewables Hydro Energy crops Bio-waste MSW Total renewable Low-C large-scale electrical generation Other fossil
35.5%
1998
0.10
2
3
4
0.10
6.5 11.4 10.0 3.75 0.25 2.2 34.1
3.3 11.4 5.0 3.75 0.25 2.2 25.9
0.2 11.4 0.5 3.75 0.25 0.0 16.1
3.3 5.7 0.5 3.75 0.25 2.2 15.7
0.61 — 0.04 0.15 0.90 11.4
0.89 10.2 5.7 1.9 52.8 52
0.89 10.2 5.7 1.9 44.6 0
0.89 1.8 5.7 0 24.5 19
0.79 1.8 1.2 0 19.5 0
266
106
106
106
106
Fig. 2. Final energy consumption in the UK, 2003 [5].
60
Million tonnes of carbon
50 40 30 20 10 0 1990
1993
1996
Power stations
1999
2003
Industrial combustion
Transport
Domestic
Services and agriculture
Other sectors
Fig. 3. UK carbon dioxide emissions by source [5].
just might enable economic growth to be decoupled from carbon dioxide emissions. The final energy demands in the RCEP’s four scenarios are summarised in Table 1. The corresponding energy supply systems are summarised in Table 2, in terms of output of electricity, heat and intermediate energy carriers (primarily hydrogen for use as a transport fuel). In addition, ‘‘high-grade’’ heat, used primarily for energyintensive industrial processes, is supplied in all scenarios by natural gas. Industrial, commercial and domestic demand for electrical energy is reduced in some scenarios through improvements in the efficiency of appliances and machines, but it is recognised that such reductions would represent a
reversal of current trends. Low grade heat is used primarily for space- and water-heating in domestic and commercial buildings. The reductions in some scenarios are assumed to be achieved primarily by improving the energy efficiency of the UK building stock, with further reductions in carbon emissions achieved by using biomass and waste as fuels in heat-only and CHP plants. Transport is seen as continuing to be dependant on fossil hydrocarbons, although the carbon efficiency of transport is assumed to improve through a combination of incremental technological development, larger shifts such as use of hydrogen produced from fossil fuels but with higher well-to-wheel carbon efficiency, and modal shifts (primarily from road to rail) to carry both people and goods with lower carbon dioxide emissions.3 Scenario 1 represents a ‘‘technology can fix it’’ approach. It assumes that final demand returns to the 1998 levels and that the 60% reduction is achieved solely by technological change with the maximum deployment of renewables and maximum use of electrical generation using nuclear sources or fossil fuels. In this scenario, energy crops, agricultural and forestry waste and municipal solid waste (MSW) are used as fuels in CHP plants or heat-only plants generating low-grade heat output. Scenario 2 and 3 assume that energy demand can be reduced by 36% below the 1998 level. The largest reduction is in low-grade heat (see Table 1) brought about primarily by improving the energy efficiency of the building stock. In scenario 2 the reduced demand is met by a combination of renewable sources and fossil fuels, while scenario 3 is based 3
The role of air transport was considered in a subsequent RCEP study [6], which has also triggered an intense debate over the need to constrain growth in demand.
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on renewable sources plus large controllable generating plants using nuclear fission or fossil fuel with sequestration of carbon dioxide. Scenario 4 represents the most extreme case: a very large reduction in demand (corresponding, inter alia, to replacing or retrofitting most of the UK building stock to Nordic standards) supplied from renewable sources with no large generating stations. However, the reduction in demand means that the energy provided by renewable sources can still be less than in scenario 1. The scenario analysis underlines the importance of improving the efficiency of energy use in the UK, and highlights the need to reduce energy use in buildings and to use appropriate fuels such as biomass to provide ‘‘lowgrade’’ heat [4]. Agricultural waste, energy crops and MSW represent significant resources which are currently essentially unused in the UK; their significance is discussed further below. This emerges as being at least as significant as the more obvious public debate over the future of nuclear power for electricity generation. The scenarios also differ in their assumptions over the energy sources used for electricity. The use of renewables is based on assessments of the cost-effective available resource in the UK [7]. There is limited hydro-electric generation capacity available, and the scenarios assume only modest expansion. On- and off-shore wind is assumed to expand, a development which has already started in the UK. Wave generation is assumed to have developed to make a modest contribution by 2050, with a further small contribution from tidal-stream turbines. Some scenarios also assume construction of tidal barrages; there is significant technical scope for developing this resource but it may not prove to be environmentally or socially acceptable.4 Even with maximum use of renewable sources, there is continuing debate over the proportion of embedded and possibly intermittent generation which can be accommodated in the system for distribution and supply of electrical energy. Fast-response high-density energy storage is clearly important to smooth out short-term imbalance between supply and demand. In the UK, this is currently achieved by pumped storage but the scope for expansion is at best limited; thus there is a clear need for new energy storage technologies. Scenarios 1 and 3 assume that such new technologies do not emerge, so that intermittent renewable generation of electricity must be ‘‘backed up’’ by a proportion of controllable generating stations. In the kind of lower carbon energy systems exemplified by these scenarios, the fuel options for large-scale generation are nuclear fission or alternatively fossil fuels with the carbon dioxide captured 4 One of the areas which has been considered for a tidal barrage but rejected on environmental grounds is the Bristol Channel in the South West of England. However, it is possible that this project could be revisited, on the argument that it would actually provide environmental protection against some of the effects of rising sea level.
and sequestered in geological strata, primarily saline aquifers; the estimated capacity in the UK sectors of the North and Irish seas is sufficiently large to accommodate emissions way beyond 2050 [1]. ‘‘Other fossil’’ in Table 2 refers to uses from which the carbon dioxide is emitted to the atmosphere. The scenarios also implicitly assume that hydrogen used in transport is produced from hydrocarbons but in dedicated reforming plants from which the carbon dioxide is sequestered. Thus the scenarios illustrate that the significant technological choice, at least for the UK, is not, as presented in the mass media, between renewable and nuclear power. Rather, the choice is between nuclear power and fossil-fired generation with carbon sequestration, with the proportion of either of these sources dependant on the availability of storage technology. The feasibility of carbon dioxide sequestration should be a central concern, along with the question of how much generating capacity is needed to ‘‘back up’’ intermittent renewable sources. The significance of this analysis is that, with the possible exception of scenario 4, the 60% reduction is achievable without totally novel technologies and without complete change in social and economic structures or lifestyles. As noted above, these scenarios provided the basis for assessment of the economic cost of switching to a lowercarbon economy. There is little doubt that the assessment of the cost of the transition was an important consideration leading to the political acceptance of the RCEP’s ‘‘headline’’ recommendation of a 60% reduction in carbon dioxide emissions by 2050.
5. Use of biofuels A feature of the RCEP report [1], not usual in policy documents, is frequent reference to the laws of thermodynamics. The primary reason for this is that UK energy policy has concentrated on the electricity sector, almost as if heat is not a form of energy. Results of this focus on electrical generation can be seen in the relatively slow development of the Combined Heat and Power (CHP) sector in the UK, the general resistance of local authorities and the construction sector to contemplate anything other than single-dwelling space and water heating, and cooling towers—those obvious symbols of energy waste—at electrical generating stations. The RCEP study tries to bring heat provision more centrally into energy policy. As a further result of the policy neglect of heat, biological energy resources remain essentially untapped in the UK: agricultural wastes, energy crops and MSW.5 A more recent RCEP report [8] examined biomass, to investigate its possible contribution to energy supply in the 5 For these purposes, MSW is treated as a renewable fuel, on the basis that it is available anyway but currently consigned mainly to landfill. Public resistance to recovering energy from solid waste is a UK peculiarity, not discussed here.
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UK and why the sector has been so slow to develop compared to other European countries. Austria has the most developed biomass sector in Europe. Starting from small-scale heating plants, the sector in Austria has grown over some 20 years to the point where biomass provides around 15% of primary energy. This has enabled certain Austrian provinces to achieve one of the holy grails of sustainable development: decoupling economic growth from carbon to the point where GDP has increased but carbon dioxide emissions have decreased. In Denmark, biomass is now widely used, often co-fired with coal, primarily in CHP plants. These are usually built for their heat output, for example into community heating systems, with electrical output used to back-up intermittent renewables, primarily wind. In Sweden, biomass has developed more recently but rapidly, initially for community heating and then CHP plants operated, as in Denmark, over a range of heat/power ratio. It is therefore anomalous that, in the UK, renewables still only account for just over 1% of total inland energy use, of which biomass is only a small fraction. The RCEP diagnosed one of the reasons for this failure as the complex and confused government support for biomass, exacerbated by the focus on generating electrical power with no corresponding incentives for renewable heat production. The focus on power generation seems to have been amplified by the notion that ‘‘high technology’’ processes can be developed for exploitation of biomass leading to possible export markets. One result of this approach has been the conspicuous failure of the ARBRE project in South Yorkshire, an electricity generating plant fuelled by short-rotation coppiced (SRC) willow and using Swedish biomass gasification technology. The plant failed to progress beyond start-up to enter service—for reasons which are hotly discussed. The RCEP argued that, rather than being seen as a possible fuel for power generation, biomass should be seen primarily as a local fuel for heating or CHP. Subsequent studies have confirmed this conclusion [9,10]. Local supply chains must therefore be developed and, until the longterm demand is clear, it is unreasonable to expect farmers to plant energy crops even when planting grants are available. Co-firing of biomass with coal in electrical generating stations has been promoted as an interim measure to develop a market for biomass (although RCEP were critical of some restrictions imposed by the UK regulator which greatly increase the cost of co-firing at existing power stations) by attracting the financial credits available for renewable electricity. However, while credits are available to promote the development of renewable electricity supply, there has been a marked reluctance on the part of the UK government to extend a similar approach to renewable heat supply—a further manifestation of the neglect of heat as a significant part of the total national energy budget. The Biomass Task Force, set up by the Department of the Environment Food and Rural Affairs (Defra) following the RCEP, argued that, if
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biomass is in competition with hydrocarbon fuels at current prices, the economics should favour biomass so clearly that renewable heat credits are not needed [9]. The detailed analyses of the availability of bio-energy broadly confirmed the earlier estimates summarised in Table 2. Substantial quantities of unused biomass are already available from poorly managed forest, mainly of broad-leaf trees which give a product with relatively high calorific value. Furthermore, significant quantities of biomass will become available over the next 20 years from forest plantations, primarily of Sitka spruce, developed to provide pulpwood based on projections of demand which now appear to have been too high. Fig. 4 shows estimates by the Forestry Commission for the availability of wood in the UK. They show that there is already a surplus of supply over demand, and it appears that these figures are actually underestimates of the available resource [11]. The surplus becomes much larger if agricultural residues—primarily straw—are included. This persuaded the RCEP of the need to develop a market to stimulate demand for the existing resource before there is any point in encouraging planting of energy crops. However, energy crops will also be needed if the biomass sector develops in the UK as it has elsewhere in Europe. Based on assessments of energy yield per hectare, SRC salix (willow) appears to be generally the highest yielding crop but other plants such as miscanthus (elephant grass) may be preferred where favoured by local climate and soil conditions. Fig. 5 shows the way in which the biomass sector could develop in the UK, using the estimated current supplies of wood from Fig. 4 together with agricultural residues as a basis for developing the market for energy crops, up to the level of primary energy supply in 2050 needed to provide the delivered energy required by scenarios 1 and 2 in the earlier RCEP report [1]. A phased
Fig. 4. Supply and demand of wood in Great Britain (i.e. England, Wales and Scotland) [8].
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developed more rapidly because the supply chain for vegetable oils was already in place. This serves to underline the importance of developing the supply chain for other bioenergy crops. 6. Concluding remarks
Fig. 5. Scenario to achieve 16 GW of energy from forestry, straw and energy crops [8].
approach to the development of bioenergy in the UK was foreseen: Phase 1 (2004–2012): Increasing use of both agricultural and forestry resources, and of set-aside land for energy crops. Phase 2 (2012–2018): Area producing energy crops increases to include all set-aside land. Phase 3 (2018–2025): Energy crops become established as accepted main crops. Phase 4 (2025–2050): The area of land under energy crops becomes a significant proportion of total available agricultural land. It is clear that competition for land use will be a constraint on the development of the bioenergy sector if anything like the scenario in Fig. 5 develops. The RCEP analysis leads to the conclusion that the focus should be on biofuels for heat or CHP rather than for transport. Only if surplus land is available once the heat demand is met should transport fuels be considered, because the energy yield and carbon reduction per hectare are lower than for salix or miscanthus; the RCEP analysis suggests that this will never be the case, providing a post hoc justification for the assumption in Tables 1 and 2 that transport will continue to represent the primary demand for hydrocarbons. This conclusion runs counter to the EU’s policy of promoting biofuels for transport, and therefore begs the question of why transport fuels, with their less efficient use of agricultural land, have developed ahead of fuels for heat and CHP. One possible reason, which seems plausible to many involved in this sector, is that biofuels for transport have provided a way to support agricultural activities in spite of the Common Agricultural Policy. More pragmatically, the market for liquid fuels such as biodiesel has
The work of the Royal Commission on Environmental Pollution reviewed here provides both positive and negative examples of success in using scientific analysis to underpin policy recommendations: positive in the sense that the ‘‘headline’’ recommendation on carbon dioxide emissions has been accepted by the UK Government; negative in the sense that more specific recommendations, such as actions to promote the development of biomass as a renewable energy source, have not as yet been implemented. However, the overall message, that climate change is a real threat and that action to mitigate it is possible, does now appear to be widely accepted. The key question is not whether new energy technologies can be developed; on the contrary, the RCEP analysis shows that the necessary reductions in carbon dioxide emissions could be achieved using known technology. The real question is whether the political will can be found to take the necessary action. References [1] Royal Commission on Environmental Pollution Energy—the changing climate. London: The Stationery Office, 2000. [2] Mitchell CA, Carew AL, Clift R. The role of the professional engineer and scientist in sustainable development. In: Azapagic A, Perdan S, Clift R, editors. Sustainable development in practice—case studies for engineers and scientists. Chichester: Wiley; 2004. p. 29–55 [Chapter 2]. [3] Clift R, Hoskins BJ. Energy and climate change—mission possible. The Chemical Engineer, August Issue 2005. p. 21–5. [4] House of Lords: Energy Efficiency, Science and Technology Committee, 2nd Report of Session 2005-6 (HL Paper 21-I), The Stationery Office, London, 2005. [5] Department of Trade and Industry Digest of UK Energy Statistics (DUKES), DTI, 2004. [6] Royal Commission on Environmental Pollution. The environmental effects of civil aircraft in flight. London: RCEP, 2002. [7] Energy Technology Support Unit (ETSU). New and renewable energy: prospects in the UK for the 21st century—supporting analysis, ETSU, Marwell, 1999. [8] Royal Commission on Environmental Pollution. Biomass as a renewable energy source, RCEP, London, 2004. [9] Biomass Task Force. Report to Government, Department of the Environment, Food and Rural Affairs (Defra), 2005. [10] Paul Arwas Associates. Biomass sector review for the Carbon Trust, The Carbon Trust, London, 2005. [11] Davis, J. The Forestry and Timber Association (FTA), Pers. Comm, 2006.
Energy 32 (2007) 262–268 www.elsevier.com/locate/energy
Keynote Paper
Climate change and energy policy: The importance of sustainability arguments Roland Clift Centre for Environmental Strategy, University of Surrey, Guildford, Surrey GU2 7XH, UK Received 1 November 2005
Abstract It is the stated policy of the UK government to reduce emissions of carbon dioxide by 60% by 2050. This policy, which goes far beyond commitments under the Kyoto agreement, was originally advocated by the Royal Commission on Environmental Pollution, of which the author was a member. Its acceptance was seen by many as a surprising development, possibly reflecting the strength of the underlying case. The target was developed by a three-legged argument which reflects the three components of sustainability: Environmental constraints: limits on emissions to avoid risk of major climate change; Social equity: equal per-capita allocation of emissions; Techno-economic: the feasibility and cost of reduction on this scale. Assessment of techno-economic feasibility shows that the target can be achieved economically if the efficiency of energy use is improved to achieve reduction in demand, combined with a shift to lower-carbon energy sources. The greatest scope for demand reduction lies in improving the building stock, combined with providing low-grade heat from sources such as biomass. On the supply side, the principle questions are how much controllable electricity generation is needed, and whether this capacity should be nuclear or fired by fossil fuels with the carbon dioxide formed sequestered in geological strata. Increased use of biomass is a key part of the shift to a lower carbon economy; the barriers which have retarded the development of biomass in the UK are explored. r 2006 Elsevier Ltd. All rights reserved. Keywords: Energy policy; Climate change; Energy scenario
1. Introduction The author was, until 2005, a member of the Royal Commission on Environmental Pollution (RCEP), a uniquely UK institution appointed 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. The RCEP has been in continuous existence but with rotating membership since 1970. It is constituted as a body of independent experts, standing outside the political mainstream but intended to provide advice to guide long-term environmental policy. An important role for the RCEP is to present scientific evidence and its implications which may be obvious to the scientific community but politically Corresponding author. Tel.: +44 1483 689271; fax: +44 1483 686671.
E-mail address: [email protected]. 0360-5442/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2006.07.031
inconvenient. Some of the RCEP’s reports have had a significance which extends outside the UK; for example, the concepts of Integrated Pollution Control and Best Practicable Environmental Option originated with the RCEP. In a report published in 2000 [1], the Royal Commission addressed the issue of climate change and its relationship to energy supply. The principal recommendation of the RCEP’s analysis was that carbon dioxide emissions from human activities in the UK must be reduced by 60% below 1998 levels by 2050. The year 2050 was itself chosen carefully: even the most enthusiastic advocates of nuclear fusion did not consider that it would be available before 2050, so that the target would have to be met by known energy technologies.1 At the time, this target appeared to 1 RCEP also recommended a decrease of 80% by 2100, but this longerterm target is not discussed in this paper.
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be too radical to be politically acceptable; for example, it goes way beyond negotiations under the Kyoto protocol. However, it was accepted, is now UK Government policy and progress towards the target is currently under review. The present paper reviews the argument which supported its acceptance and some of the implications of this policy. 2. The context: sustainable development The concept of sustainable development is now sufficiently well known that it will not be rehearsed here. However, a particular interpretation of sustainable development which has proved useful in teaching the concept to engineers and scientists [2] will be reviewed, because it illustrates and supports the argument developed by the RCEP [1]. The basic idea is that human activities are limited by three sets of long-term constraints, summarised by the Venn diagram in Fig. 1. Eco-centric concerns represent the constraints imposed by the fact that the earth is, in thermodynamic terms, a closed system. Thus, energy flux is received from the sun, but the ‘‘capital’’ resources available to us on a global scale are finite, as is the capacity of the biosphere to absorb or adapt to the emissions from human activities. Techno-centric concerns represent the constraints imposed by finite human abilities: the technology which we are able to deploy and the economic system within which we deploy that technology. This lobe represents the traditional scope of engineering. Socio-centric concerns represent human expectations: the need to provide a better quality of life for everyone, now and in the future (to quote from the UK Government’s interpretation of sustainable development). This lobe incorporates the principles of inter- and intra-generational equity which are central to the concept of sustainable development. Sustainable development involves moving towards complying with all three sets of constraints, not of trading off one set of objectives against another. Sustainability is to be found in the central area of Fig. 1, which meets all the sets of constraints, while
Natural resources and ecological capacity
TECHNO-CENTRIC CONCERNS
sustainable development is a process of moving towards that region. While it is recognised that Fig. 1 is a simplistic representation of a very rich concept, it has nevertheless proved to be useful as an educational device. Although not stated explicitly in the RCEP report, it is implicit that future use of fossil hydrocarbons will be constrained not by their availability but by the capacity of the biosphere to adapt to the emissions resulting from their use, specifically carbon dioxide. In other words, we already know the whereabouts of more fossil fuels than can be burned without risking disastrous climatic impacts; hydrocarbons in particular will continue to be available, albeit at prices well above historical levels (and possibly above current levels). To support this argument, current crude oil prices make it not only economic but very profitable to exploit oil sands; the quantity of ‘‘synthetic crude’’ available in Alberta is of the same order as the oil reserves in Saudi Arabia—a simple fact which is sometimes overlooked in discussions over the extent of remaining oil reserves. The driver for change in energy technology is therefore the effect of the emissions, not limited supply; as Sheikh Yamani famously put it, ‘‘The stone age did not end because we ran out of stones’’. While the conventional market system can deal with scarcity of supply through rising prices which make new reserves economic, it is necessary to invent a new mechanism to deal with scarcity of ‘‘carrying capacity’’ to absorb emissions. It remains to be seen whether emission trading systems like that being introduced in Europe will constitute an effective market, whether the price will be sufficiently high to influence energy use and whether carbon prices will be sufficiently stable for effective long-term planning and restructuring of the energy system. The Royal Commission sidestepped the continuing arguments over whether the effects of carbon dioxide emissions, can be represented in terms of a simple economic damage cost (or ‘‘externality’’) by addressing energy policy and climate change in a different way using the approach, introduced above, of recognising and trying to estimate the constraints. 3. Policy recommendations
ECO-CENTRIC CONCERNS
Techno-economic systems
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Human capital and social expectations SOCIO-CENTRIC CONCERNS
Fig. 1. Sustainability expressed as long-term constraints [2].
The Royal Commission’s report starts with an analysis of the evidence that emissions of climate-forcing ‘‘greenhouse gases’’ from human activities are causing changes in the global climate and regional weather patterns. In effect, it endorsed the conclusions of the UN Intergovernmental Panel on Climate change (IPCC). To quote the RCEP report [1], the world is now faced with a radical challenge of a totally new kind which requires an urgent responsey By the time the effects of human activities on the global climate are clear and unambiguous it would be too late to take preventive measures. This statement may not be news to the scientific community in Europe, but was necessary at the time of publication (2000) to underpin the Commission’s recommendations; although the UK government now
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stresses its belief that climate change represents a real and serious threat, this commitment has emerged since publication of the RCEP report. Of more interest here is the analysis which followed, which had three principal steps: 1. If the concentration of carbon dioxide in the atmosphere gets too high, then there will be a risk of really catastrophic climate change associated, for example, with changes in ocean circulation patterns. RCEP proposed 550 ppm as the ceiling, a constraint which must not be breached. Some would prefer a lower limit—at 550 ppm, the predicted rise in sea level is still bad news for low lying Pacific islands, for example—and information on the effects of climate change which has become available since 2000 arguably supports a lower figure. However, 550 ppm already represents a major departure from ‘‘business as usual’’ [3] and there was also a measure of political realism behind the figure (see below). 2. Working back from the 550 ppm constraint, RCEP estimated the total tolerable CO2 emissions, and then divided them by total global population to get the per capita ration. Multiplying by the population of the UK gave about 40% of current emissions—hence the recommended target of a 60% reduction below 1998 levels. This is known as the ‘‘contract-and-converge’’ principle. It simply ignores economists’ attempts to calculate an optimal level of CO2 emissions, on the basis that the damage cost or ‘‘externality’’ figures mean little when the climatic system is so complex and non-linear (and therefore chaotic) that detailed predictions of climate change and its effects, as distinct from estimating thresholds or constraints, are meaningless. 3. To explore the practicality of the 60% reduction target, RCEP developed representative scenarios to illustrate how it might be achieved (see below). Based on these scenarios, the cost of shifting to a low-carbon energy economy was subsequently estimated as about 2% of annual GDP. The cost is sometimes described as ‘‘enormous’’ but, as an economist will always ask, compared to what? The economists who produced these estimates also project 4% annual growth in GDP. So taking action to limit the potentially catastrophic effects of global climate change would merely slow down the rise in consumer spending in developed countries. Given that most forms of consumer spending in industrialised countries lead to carbon dioxide emissions, there is an argument that this in itself could have some effect in constraining the growth of climate-forcing emissions. It is interesting that, although not explicitly formulated in terms of the approach to sustainability summarised in Fig. 1, the three steps in the argument map exactly onto the three sets of constraints: ecological, societal and technoeconomic. Perhaps this illustrates the strength of this approach to sustainability analysis. To quote the RCEP
report again [1], y the UK could cut its carbon dioxide emissions by 60% by 2050. Achieving this will require vision, leadership, and action which begins now. Acceptance of the target of 60% reduction by 2050 has, so far at least, survived subsequent discussions over commitments under the Kyoto process and softening of UK government targets for shorter term reductions. In fact, the UK government has been advocating international acceptance of the 2050 target, and the Swedish government has also adopted it as a basis for energy policy.
4. Energy scenarios In order to explore the implications of a 60% reduction in carbon dioxide emissions, the RCEP constructed four scenarios to illustrate measures by which it might be achieved. These scenarios are only illustrations, not intended to be interpreted as predictions or projections, but they enabled rough estimates of the cost of the change (see above). Scenarios 1 and 4 were deliberately selected as extremes—respectively, ‘‘techno-fix’’ and ‘‘ecological living’’ —with scenarios 2 and 3 intended to represent more realistic energy futures. They had a number of common features. They were based on known technologies, assuming that electrical generation by nuclear fusion is not available by 2050 (see above). They took as their starting point the 1998 pattern of energy use in the UK, summarised in Table 1. Fig. 2 shows energy use updated to 2003, while Fig. 3 shows how UK carbon dioxide emissions have changed since 1990. Compared to continental European countries at comparable latitudes, domestic energy use is high because of the relatively poor energy performance of the UK building stock and the almost complete absence of heating systems distributing ‘‘low-grade’’ heat; the principal fuels for space and water heating are natural gas and electrical resistive heating.2 For obvious geographical reasons, the electricity grid in the UK is separate from that of continental Europe (apart from limited imports via a cross-channel link from France). Most of the decline in carbon dioxide emissions since 1990 is attributable to replacement of coal by natural gas in electricity generation (Fig. 3) although coal use has risen again since 1999. However, the proportion of renewable sources in the UK electricity system is still low by European Standards: only just over 1% of total inland energy use even in 2004. These features of the UK energy sector present possible savings in carbon intensity which are not available in other European countries, and which 2 Off-peak ‘‘night storage’’ heating is still used in the UK. It has been argued, principally by advocates of nuclear power, that this is to be encouraged, on the basis that future energy systems will be dominated by low-carbon fixed-output electricity generation. RCEP did not subscribe to this view, rejecting its implication that new buildings should be equipped with electrical heating to fit hypothetical energy system which might possibly exist at some future date. A subsequent study by the House of Lords [4] endorsed this conclusion.
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Table 1 Final energy consumption in 2050 by end-use (annual averages in GW) [1]
Table 2 Outputs from energy sources in 2050 (annual averages in GW) [1]
End-use category
Source
Scenario
High-grade heat Electricity Low-grade heat Transport Total
1 (as 1998)
2
3
4
87 32 16 70 205
44 24 12 53 132
44 24 12 53 132
30 21 11 47 109
12.3%
Transport
21.9%
Domestic Industry Services (including agriculture) 30.1%
Scenario 1
Intermittent renewables On-shore wind Off-shore wind Photovoltaic Wave Tidal stream Tidal barrage Total Other renewables Hydro Energy crops Bio-waste MSW Total renewable Low-C large-scale electrical generation Other fossil
35.5%
1998
0.10
2
3
4
0.10
6.5 11.4 10.0 3.75 0.25 2.2 34.1
3.3 11.4 5.0 3.75 0.25 2.2 25.9
0.2 11.4 0.5 3.75 0.25 0.0 16.1
3.3 5.7 0.5 3.75 0.25 2.2 15.7
0.61 — 0.04 0.15 0.90 11.4
0.89 10.2 5.7 1.9 52.8 52
0.89 10.2 5.7 1.9 44.6 0
0.89 1.8 5.7 0 24.5 19
0.79 1.8 1.2 0 19.5 0
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106
106
106
106
Fig. 2. Final energy consumption in the UK, 2003 [5].
60
Million tonnes of carbon
50 40 30 20 10 0 1990
1993
1996
Power stations
1999
2003
Industrial combustion
Transport
Domestic
Services and agriculture
Other sectors
Fig. 3. UK carbon dioxide emissions by source [5].
just might enable economic growth to be decoupled from carbon dioxide emissions. The final energy demands in the RCEP’s four scenarios are summarised in Table 1. The corresponding energy supply systems are summarised in Table 2, in terms of output of electricity, heat and intermediate energy carriers (primarily hydrogen for use as a transport fuel). In addition, ‘‘high-grade’’ heat, used primarily for energyintensive industrial processes, is supplied in all scenarios by natural gas. Industrial, commercial and domestic demand for electrical energy is reduced in some scenarios through improvements in the efficiency of appliances and machines, but it is recognised that such reductions would represent a
reversal of current trends. Low grade heat is used primarily for space- and water-heating in domestic and commercial buildings. The reductions in some scenarios are assumed to be achieved primarily by improving the energy efficiency of the UK building stock, with further reductions in carbon emissions achieved by using biomass and waste as fuels in heat-only and CHP plants. Transport is seen as continuing to be dependant on fossil hydrocarbons, although the carbon efficiency of transport is assumed to improve through a combination of incremental technological development, larger shifts such as use of hydrogen produced from fossil fuels but with higher well-to-wheel carbon efficiency, and modal shifts (primarily from road to rail) to carry both people and goods with lower carbon dioxide emissions.3 Scenario 1 represents a ‘‘technology can fix it’’ approach. It assumes that final demand returns to the 1998 levels and that the 60% reduction is achieved solely by technological change with the maximum deployment of renewables and maximum use of electrical generation using nuclear sources or fossil fuels. In this scenario, energy crops, agricultural and forestry waste and municipal solid waste (MSW) are used as fuels in CHP plants or heat-only plants generating low-grade heat output. Scenario 2 and 3 assume that energy demand can be reduced by 36% below the 1998 level. The largest reduction is in low-grade heat (see Table 1) brought about primarily by improving the energy efficiency of the building stock. In scenario 2 the reduced demand is met by a combination of renewable sources and fossil fuels, while scenario 3 is based 3
The role of air transport was considered in a subsequent RCEP study [6], which has also triggered an intense debate over the need to constrain growth in demand.
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on renewable sources plus large controllable generating plants using nuclear fission or fossil fuel with sequestration of carbon dioxide. Scenario 4 represents the most extreme case: a very large reduction in demand (corresponding, inter alia, to replacing or retrofitting most of the UK building stock to Nordic standards) supplied from renewable sources with no large generating stations. However, the reduction in demand means that the energy provided by renewable sources can still be less than in scenario 1. The scenario analysis underlines the importance of improving the efficiency of energy use in the UK, and highlights the need to reduce energy use in buildings and to use appropriate fuels such as biomass to provide ‘‘lowgrade’’ heat [4]. Agricultural waste, energy crops and MSW represent significant resources which are currently essentially unused in the UK; their significance is discussed further below. This emerges as being at least as significant as the more obvious public debate over the future of nuclear power for electricity generation. The scenarios also differ in their assumptions over the energy sources used for electricity. The use of renewables is based on assessments of the cost-effective available resource in the UK [7]. There is limited hydro-electric generation capacity available, and the scenarios assume only modest expansion. On- and off-shore wind is assumed to expand, a development which has already started in the UK. Wave generation is assumed to have developed to make a modest contribution by 2050, with a further small contribution from tidal-stream turbines. Some scenarios also assume construction of tidal barrages; there is significant technical scope for developing this resource but it may not prove to be environmentally or socially acceptable.4 Even with maximum use of renewable sources, there is continuing debate over the proportion of embedded and possibly intermittent generation which can be accommodated in the system for distribution and supply of electrical energy. Fast-response high-density energy storage is clearly important to smooth out short-term imbalance between supply and demand. In the UK, this is currently achieved by pumped storage but the scope for expansion is at best limited; thus there is a clear need for new energy storage technologies. Scenarios 1 and 3 assume that such new technologies do not emerge, so that intermittent renewable generation of electricity must be ‘‘backed up’’ by a proportion of controllable generating stations. In the kind of lower carbon energy systems exemplified by these scenarios, the fuel options for large-scale generation are nuclear fission or alternatively fossil fuels with the carbon dioxide captured 4 One of the areas which has been considered for a tidal barrage but rejected on environmental grounds is the Bristol Channel in the South West of England. However, it is possible that this project could be revisited, on the argument that it would actually provide environmental protection against some of the effects of rising sea level.
and sequestered in geological strata, primarily saline aquifers; the estimated capacity in the UK sectors of the North and Irish seas is sufficiently large to accommodate emissions way beyond 2050 [1]. ‘‘Other fossil’’ in Table 2 refers to uses from which the carbon dioxide is emitted to the atmosphere. The scenarios also implicitly assume that hydrogen used in transport is produced from hydrocarbons but in dedicated reforming plants from which the carbon dioxide is sequestered. Thus the scenarios illustrate that the significant technological choice, at least for the UK, is not, as presented in the mass media, between renewable and nuclear power. Rather, the choice is between nuclear power and fossil-fired generation with carbon sequestration, with the proportion of either of these sources dependant on the availability of storage technology. The feasibility of carbon dioxide sequestration should be a central concern, along with the question of how much generating capacity is needed to ‘‘back up’’ intermittent renewable sources. The significance of this analysis is that, with the possible exception of scenario 4, the 60% reduction is achievable without totally novel technologies and without complete change in social and economic structures or lifestyles. As noted above, these scenarios provided the basis for assessment of the economic cost of switching to a lowercarbon economy. There is little doubt that the assessment of the cost of the transition was an important consideration leading to the political acceptance of the RCEP’s ‘‘headline’’ recommendation of a 60% reduction in carbon dioxide emissions by 2050.
5. Use of biofuels A feature of the RCEP report [1], not usual in policy documents, is frequent reference to the laws of thermodynamics. The primary reason for this is that UK energy policy has concentrated on the electricity sector, almost as if heat is not a form of energy. Results of this focus on electrical generation can be seen in the relatively slow development of the Combined Heat and Power (CHP) sector in the UK, the general resistance of local authorities and the construction sector to contemplate anything other than single-dwelling space and water heating, and cooling towers—those obvious symbols of energy waste—at electrical generating stations. The RCEP study tries to bring heat provision more centrally into energy policy. As a further result of the policy neglect of heat, biological energy resources remain essentially untapped in the UK: agricultural wastes, energy crops and MSW.5 A more recent RCEP report [8] examined biomass, to investigate its possible contribution to energy supply in the 5 For these purposes, MSW is treated as a renewable fuel, on the basis that it is available anyway but currently consigned mainly to landfill. Public resistance to recovering energy from solid waste is a UK peculiarity, not discussed here.
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UK and why the sector has been so slow to develop compared to other European countries. Austria has the most developed biomass sector in Europe. Starting from small-scale heating plants, the sector in Austria has grown over some 20 years to the point where biomass provides around 15% of primary energy. This has enabled certain Austrian provinces to achieve one of the holy grails of sustainable development: decoupling economic growth from carbon to the point where GDP has increased but carbon dioxide emissions have decreased. In Denmark, biomass is now widely used, often co-fired with coal, primarily in CHP plants. These are usually built for their heat output, for example into community heating systems, with electrical output used to back-up intermittent renewables, primarily wind. In Sweden, biomass has developed more recently but rapidly, initially for community heating and then CHP plants operated, as in Denmark, over a range of heat/power ratio. It is therefore anomalous that, in the UK, renewables still only account for just over 1% of total inland energy use, of which biomass is only a small fraction. The RCEP diagnosed one of the reasons for this failure as the complex and confused government support for biomass, exacerbated by the focus on generating electrical power with no corresponding incentives for renewable heat production. The focus on power generation seems to have been amplified by the notion that ‘‘high technology’’ processes can be developed for exploitation of biomass leading to possible export markets. One result of this approach has been the conspicuous failure of the ARBRE project in South Yorkshire, an electricity generating plant fuelled by short-rotation coppiced (SRC) willow and using Swedish biomass gasification technology. The plant failed to progress beyond start-up to enter service—for reasons which are hotly discussed. The RCEP argued that, rather than being seen as a possible fuel for power generation, biomass should be seen primarily as a local fuel for heating or CHP. Subsequent studies have confirmed this conclusion [9,10]. Local supply chains must therefore be developed and, until the longterm demand is clear, it is unreasonable to expect farmers to plant energy crops even when planting grants are available. Co-firing of biomass with coal in electrical generating stations has been promoted as an interim measure to develop a market for biomass (although RCEP were critical of some restrictions imposed by the UK regulator which greatly increase the cost of co-firing at existing power stations) by attracting the financial credits available for renewable electricity. However, while credits are available to promote the development of renewable electricity supply, there has been a marked reluctance on the part of the UK government to extend a similar approach to renewable heat supply—a further manifestation of the neglect of heat as a significant part of the total national energy budget. The Biomass Task Force, set up by the Department of the Environment Food and Rural Affairs (Defra) following the RCEP, argued that, if
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biomass is in competition with hydrocarbon fuels at current prices, the economics should favour biomass so clearly that renewable heat credits are not needed [9]. The detailed analyses of the availability of bio-energy broadly confirmed the earlier estimates summarised in Table 2. Substantial quantities of unused biomass are already available from poorly managed forest, mainly of broad-leaf trees which give a product with relatively high calorific value. Furthermore, significant quantities of biomass will become available over the next 20 years from forest plantations, primarily of Sitka spruce, developed to provide pulpwood based on projections of demand which now appear to have been too high. Fig. 4 shows estimates by the Forestry Commission for the availability of wood in the UK. They show that there is already a surplus of supply over demand, and it appears that these figures are actually underestimates of the available resource [11]. The surplus becomes much larger if agricultural residues—primarily straw—are included. This persuaded the RCEP of the need to develop a market to stimulate demand for the existing resource before there is any point in encouraging planting of energy crops. However, energy crops will also be needed if the biomass sector develops in the UK as it has elsewhere in Europe. Based on assessments of energy yield per hectare, SRC salix (willow) appears to be generally the highest yielding crop but other plants such as miscanthus (elephant grass) may be preferred where favoured by local climate and soil conditions. Fig. 5 shows the way in which the biomass sector could develop in the UK, using the estimated current supplies of wood from Fig. 4 together with agricultural residues as a basis for developing the market for energy crops, up to the level of primary energy supply in 2050 needed to provide the delivered energy required by scenarios 1 and 2 in the earlier RCEP report [1]. A phased
Fig. 4. Supply and demand of wood in Great Britain (i.e. England, Wales and Scotland) [8].
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developed more rapidly because the supply chain for vegetable oils was already in place. This serves to underline the importance of developing the supply chain for other bioenergy crops. 6. Concluding remarks
Fig. 5. Scenario to achieve 16 GW of energy from forestry, straw and energy crops [8].
approach to the development of bioenergy in the UK was foreseen: Phase 1 (2004–2012): Increasing use of both agricultural and forestry resources, and of set-aside land for energy crops. Phase 2 (2012–2018): Area producing energy crops increases to include all set-aside land. Phase 3 (2018–2025): Energy crops become established as accepted main crops. Phase 4 (2025–2050): The area of land under energy crops becomes a significant proportion of total available agricultural land. It is clear that competition for land use will be a constraint on the development of the bioenergy sector if anything like the scenario in Fig. 5 develops. The RCEP analysis leads to the conclusion that the focus should be on biofuels for heat or CHP rather than for transport. Only if surplus land is available once the heat demand is met should transport fuels be considered, because the energy yield and carbon reduction per hectare are lower than for salix or miscanthus; the RCEP analysis suggests that this will never be the case, providing a post hoc justification for the assumption in Tables 1 and 2 that transport will continue to represent the primary demand for hydrocarbons. This conclusion runs counter to the EU’s policy of promoting biofuels for transport, and therefore begs the question of why transport fuels, with their less efficient use of agricultural land, have developed ahead of fuels for heat and CHP. One possible reason, which seems plausible to many involved in this sector, is that biofuels for transport have provided a way to support agricultural activities in spite of the Common Agricultural Policy. More pragmatically, the market for liquid fuels such as biodiesel has
The work of the Royal Commission on Environmental Pollution reviewed here provides both positive and negative examples of success in using scientific analysis to underpin policy recommendations: positive in the sense that the ‘‘headline’’ recommendation on carbon dioxide emissions has been accepted by the UK Government; negative in the sense that more specific recommendations, such as actions to promote the development of biomass as a renewable energy source, have not as yet been implemented. However, the overall message, that climate change is a real threat and that action to mitigate it is possible, does now appear to be widely accepted. The key question is not whether new energy technologies can be developed; on the contrary, the RCEP analysis shows that the necessary reductions in carbon dioxide emissions could be achieved using known technology. The real question is whether the political will can be found to take the necessary action. References [1] Royal Commission on Environmental Pollution Energy—the changing climate. London: The Stationery Office, 2000. [2] Mitchell CA, Carew AL, Clift R. The role of the professional engineer and scientist in sustainable development. In: Azapagic A, Perdan S, Clift R, editors. Sustainable development in practice—case studies for engineers and scientists. Chichester: Wiley; 2004. p. 29–55 [Chapter 2]. [3] Clift R, Hoskins BJ. Energy and climate change—mission possible. The Chemical Engineer, August Issue 2005. p. 21–5. [4] House of Lords: Energy Efficiency, Science and Technology Committee, 2nd Report of Session 2005-6 (HL Paper 21-I), The Stationery Office, London, 2005. [5] Department of Trade and Industry Digest of UK Energy Statistics (DUKES), DTI, 2004. [6] Royal Commission on Environmental Pollution. The environmental effects of civil aircraft in flight. London: RCEP, 2002. [7] Energy Technology Support Unit (ETSU). New and renewable energy: prospects in the UK for the 21st century—supporting analysis, ETSU, Marwell, 1999. [8] Royal Commission on Environmental Pollution. Biomass as a renewable energy source, RCEP, London, 2004. [9] Biomass Task Force. Report to Government, Department of the Environment, Food and Rural Affairs (Defra), 2005. [10] Paul Arwas Associates. Biomass sector review for the Carbon Trust, The Carbon Trust, London, 2005. [11] Davis, J. The Forestry and Timber Association (FTA), Pers. Comm, 2006.