6.6 Long-term energy scenarios

Outline

6 Energy in a sustainable future

To begin to understand the range of long-term future possibilities, let us look briefly at two major studies of future sustainable energy options, the first addressing the UK situation, the second taking a world perspective.

6.6.1 The Royal Commission on environmental pollution scenarios

The UK's Royal Commission on Environmental Pollution produced (RCEP) its 22nd report Energy: the Changing Climate in June 2000. The Commission examined what changes would be needed in Britain's energy systems if, as suggested by the various reports of the Intergovernmental Panel on Climate Change (IPCC, 2001), it should prove necessary to reduce the country's emissions of greenhouse gases by about 60 per cent by 2050.

The Commission investigated the various possibilities very thoroughly and summarised them in four ‘scenarios’ for 2050. Scenarios are not predictions of what will happen, but plausible outlines of what could happen, under given conditions. In all four scenarios, the overall contribution from fossil fuels is reduced to approximately 40 per cent of current consumption, consistent with the 60 per cent reduction in fossil fuel use required to achieve a 60 per cent cut in CO₂ emissions.

The RCEP scenarios are summarised in Box 4. They demonstrate that it would be feasible for the UK to progress towards much greater sustainability (in terms of reducing CO₂ emissions) in its energy systems over the next 50 years. They also show that there are a number of ways in which this could be achieved.

Box 4: Four energy scenarios for the UK in 2050

Four scenarios were constructed to illustrate the options available for balancing demand and supply for energy in the middle of the twenty-first century if the UK has to reduce carbon dioxide emissions from the burning of fossil fuels by 60 per cent.

Scenario 1: no increase on 1998 demand, combination of renewables and either nuclear power stations or large fossil fuel power stations at which carbon dioxide is recovered and disposed of.

Scenario 2: demand reductions, renewables (no nuclear power stations or routine use of large fossil fuel power stations).

Scenario 3: demand reductions, combination of renewables and either nuclear power stations or large fossil fuel power stations at which carbon dioxide is recovered and disposed of.

Scenario 4: very large demand reductions, renewables (no nuclear power stations or routine use of large fossil fuel power stations).

The key parameters for these four scenarios are as follows:

	Scenario 1	Scenario 2	Scenario 3	Scenario 4
Percentage reduction in 1997 carbon dioxide emissions	57	60	60	60
DEMAND (percent reduction from 1998 final consumption)
• low-grade heat	0	50	50	66
• high-grade heat	0	25	25	33
• electricity	0	25	25	33
• transport	0	25	25	33
• Total	0	36	36	47
SUPPLY (GW) (Annual average rate)
• fossil fuels	106	106	106	106
• intermittent renewables	34	26	16	16
• other renewables	19	19	9	4
• baseload stations (either nuclear or fossil fuel with carbon dioxide recovery)	52	0	19	0

Source: Royal Commission on Environmental Pollution, 2000 ©

The actual outcome over coming decades will depend on the extent to which we change our lifestyles and our technologies in order to conserve energy; how effective we are in generating and using it more efficiently; how rapidly we choose to develop and deploy renewable energy sources; how large a role we choose to give to nuclear power; and whether or not we decide to implement carbon sequestration and other technologies for ‘cleaning-up’ fossil fuels.

6.6.2 The World Energy Council scenarios

What are the possibilities for radical changes in our energy systems when viewed from a world perspective? There have been numerous studies of the various future options for the world's energy systems. One of the most recent and most comprehensive was produced in 1998 by the International Institute for Applied Systems Analysis (IIASA) and the World Energy Council (WEC), a version of which was published in 2000 as part of the United Nations’ World Energy Assessment (United Nations Development Programme, 2000). IIASA is a leading ‘think tank’ based in Austria, whilst the WEC is a body that represents the world's main energy producers and utilities. For simplicity, we shall refer to their scenarios here as the World Energy Council (WEC) scenarios.

Figure 56: (a) Global primary energy requirements, 1850–1990, and projected requirements 1990–2100 in the three World Energy Council scenario 'cases', A, B and C. World energy use here includes commercially traded energy only; (b) World population, 1850–1990 and projected population, 1990–2100 (see text).

There are six WEC scenarios in all, and these have been grouped into three ‘cases’, A, B and C. Case B includes only one scenario, termed ‘Middle Course’. Case A consists of three ‘High Growth’ scenarios, and case C includes two ‘Ecologically Driven’ scenarios.

Each scenario incorporates different assumptions about rates of economic growth and the distribution of that growth between rich and poor countries; about the choices that are made between different energy technologies and the rapidity with which they are developed; and regarding the extent to which ecological imperatives are given priority in coming decades. They all assume that world population will increase from its current (2000) level of around 6.1 billion to 10.1 billion by 2050 and 11.7 billion by 2100. (More recent UN projections, however, suggest that these figures may be over-estimates, with 9 billion as the new median population estimate for 2050 (United Nations, 2001). Other recent research also suggests that world population is likely to peak before the end of the twenty-first century and then begin to decline. (Lutz et al., 2001)).

The results of these assumptions are shown in Figure 56 which also shows world population growth from 1850 to 2000 alongside the various scenario projections to 2100.

In all three High Growth scenarios, the world's economy expands very rapidly, at an annual average rate of 2.5 per cent per annum – significantly faster than the historic growth rate of about 2 per cent per year. In all of them, primary energy intensity (the amount of primary energy required to produce a dollar's worth of output in the economy) reduces quite rapidly, reflecting a fairly strong commitment to energy efficiency measures and/or dematerialisation. The three scenarios differ mainly in their choices of energy supply technologies. One is based on ample supplies of oil and gas; another envisages a return to coal; and the third has an emphasis on non-fossil sources, mainly renewables with some nuclear. By 2100, the High Growth scenarios all envisage world primary energy consumption rising to 1859 exajoules, more than four times the 2000 level.

In the single Middle Course scenario, economic growth is lower than in the High Growth scenarios, averaging around 2.1 per cent per annum, close to the historic average rate. Primary energy intensity improves rather more slowly, reflecting a slightly lower world-wide emphasis on energy efficiency improvement. Energy supplies come from a wide variety of fossil, nuclear and renewable sources, and by 2100 total primary energy consumption has reached 1464 EJ, over three times the 2000 level.

In the two Ecologically Driven scenarios, world economic growth is 2.2 per cent per annum, slightly higher than in Middle Course, but there is a very high emphasis on improving energy efficiency, reflected in substantially lower primary energy intensity figures. Both scenarios feature a strong development of renewables, alongside a continued use of oil, coal and natural gas. In one scenario, nuclear energy is phased out by 2100 whereas in the other some nuclear power is retained. Overall primary energy consumption increases to 880 EJ by 2100, just over twice the 2000 level.

The WEC authors conclude that, judged in terms of their sustainability, one of the High Growth scenarios (the third) includes many elements favouring sustainable development, though the other two High Growth scenarios do not. The Middle Course scenario, however, falls short of fulfilling most of the conditions for sustainable development.

The Ecologically Driven scenarios, unsurprisingly, are much more compatible with sustainable development criteria, although one of them requires a more radical departure from current policies since it envisages a phasing-out of nuclear energy.

The overall message of the WEC scenarios, examining possible solutions at a world scale, is similar to that of the RCEP scenarios for Britain: that progress to much greater sustainability in our energy systems is feasible over the next 50–100 years; that there are a number of different paths to sustainability; and that some paths are probably better than others.