T206 Long Tour 6 Energy in a Sustainable Future








<< Back to Taster home page << Back to T206 Home Page << Copyright Notice

6. Energy in a Sustainable Future

So far, we have briefly introduced three key approaches to improving the sustainability of human energy use in the future. These are:

(a) ‘Cleaning-up’ fossil and nuclear technologies

(b) Switching to renewable energy sources

(a) ‘Cleaning-up’ fossil and nuclear technologies

This means mitigating some of the adverse ‘environmental’ consequences of fossil and nuclear fuel use through the introduction of new, ‘clean’ technologies that should substantially reduce pollution emissions and health hazards. These include ‘supply-side’ measures to improve the efficiency with which fossil fuels are converted into electricity in power stations; cleaner and more efficient combustion methods; the increasing use of ‘waste’ heat in combined heat-and-power schemes; and ‘end of pipe’ technologies to intercept and store pollutants before they enter the environment. This approach also includes ‘carbon sequestration’ [Box 1.3] and ‘fuel switching’ – shifting our energy use towards less-polluting fuels, for example from coal to natural gas. It may also be possible to ‘clean up’ nuclear power by adopting more advanced technologies that are safer and entail the emission of fewer radioactive substances over the entire nuclear fuel cycle.

Box 1.3 Carbon Sequestration

One way of mitigating climate change that could be important is called ‘carbon sequestration’. To sequester means to ‘put away’, and sequestration of carbon essentially involves finding ways of removing the carbon generated by fossil fuel burning and storing it so that it cannot find its way back into the atmosphere.

One way of sequestering carbon is to plant additional trees which ‘soak up’ CO₂ from the atmosphere while they are growing. However, whilst this could provide a partial response to the problem of rising CO₂ levels, the sheer magnitude of world emissions is now so great that sequestration in forests alone is probably impractical. It has been estimated that to sequester in trees the carbon produced by world fossil fuel combustion over the next 50 years would require the afforestation of an area the size of Europe from the Atlantic to the Urals. (RCEP 2000). Also, when these trees eventually decayed and died, they would emit a similar quantity of CO₂ to that which they absorbed during growth, so it would be necessary to replace the old trees with new ones on a indefinite basis.

However wood fuel from fast-growing plantations, managed sustainably, could be harvested and used as a substitute for fossil fuels, instead of simply being allowed to grow to maturity and then decay. This would offset the carbon emissions that would otherwise have been generated by burning the fossil fuels.

Another approach to sequestering CO₂ is to extract it after combustion in, for example, a power station and store it in some suitable location. It appears to be technically possible to transport by pipeline large quantities of post-combustion CO₂ and store it indefinitely in disused oil or gas wells or in saline aquifers beneath the sea bed (Figure 1.54). Further research is required to confirm the feasibility, security, safety and economic viability of such techniques. They would only be a realistic option in the case of power stations or similar large installations: it would hardly be practicable to apply this approach to emissions from vehicles or homes.

Figure 1.54 Norwegian Statoil’s Sleipner field project. Gas from this field has a very high CO₂ content. Excess CO₂ is pumped into a saline aquifer, the Utsira formation, about 800 m below the sea bed. A million tonnes per year of CO₂ are ‘sequestered’ in this way
(This figure will open in a new window)

(b) Switching to renewable energy sources

The use of renewable energy usually involves environmental impacts of some kind, but these are normally lower than those of fossil or nuclear sources.

Approaches (a) and (b) are essentially ‘supply-side’ measures – applied at the supply end of the long chain that leads from primary energy production to useful energy consumption.

(c) Using energy more efficiently.

This, as we have seen, involves a mixture of social and technological options, applied at the demand-side of the energy chain.

How might these three approaches to improving the future sustainability of our energy systems be combined in future? What are the various possibilities, and what are the main factors that will determine the ultimate outcomes?

Changing Patterns of Energy Use

Before considering the feasibility, and the plausibility, of radical changes in patterns of energy production and consumption, of the kind that will be needed during first half of the twenty-first century if we are to progress towards sustainability, it is useful to recall the profound changes that have already occurred in our energy systems during the latter half of the twentieth century.

In Britain just after World War II most homes and other buildings were heated by coal. Most electricity generation was coal-fired, and most rail transport was propelled by coal-burning steam engines. Coal combustion caused major pollution problems, including the notorious London ‘smogs’ which in most winters caused the premature deaths of hundreds (and occasionally thousands) of people until the introduction of the Clean Air Act in 1956.

Coal miners perished in their dozens, and sometimes hundreds, in mining accidents every year, and many others died slowly of lung diseases caused by inhaling coal dust. Open coal fires in most houses were so inefficient that, despite consuming large quantities of energy, they only heated a few rooms effectively whilst the rest remained cold.

Motor cars were still owned only by a minority and air travel was confined to a small elite. Most people travelled by bus, train, cycle or on foot. Journeys were relatively few, compared with today, and usually over quite short distances.

Since the late 1940s, the UK’s energy systems have been transformed. Natural gas, which burns much more cleanly and efficiently, was introduced very rapidly to British homes and buildings from the 1970s, after its discovery beneath the North Sea, and has now replaced coal as the main heating fuel for buildings. Most homes now have gas-fired central heating systems which ensure that the whole house is maintained at a comfortable temperature.

Coal is still used for electricity generation, but flue gas desulphurization and electrostatic precipitators now greatly reduce emissions of sulphur dioxide and particulates. In new power stations, coal is increasingly being replaced by gas, which can be burned very cleanly and efficiently using combined cycle gas turbines. Nuclear power, since its modest beginnings at Calder Hall in 1956, now contributes around one-quarter of UK electricity.

Cars are now owned by the majority, air travel overseas has become a mass market, railways are powered mainly by electricity, and travel overall, measured in passenger-kilometres, has tripled since the 1950s (Figure 1.50). Britain is currently a net exporter of oil, thanks to its large North Sea reserves, whereas before the 1970s all our oil was imported.

The dramatic changes that have occurred in Britain’s energy systems during the past 50 years have, broadly, been paralleled in most ‘developed’ countries over the same period. Examples of changing patterns of energy use in other EU countries are given in Chapters 2 and 3.

Given the scale and profundity of the changes over the past half-century, it does not seem unrealistic to suggest that equally-profound changes could well occur over the next 50 to 100 years, as we attempt to improve the sustainability of our energy systems, nationally and globally.

Long-Term Energy Scenarios

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.

The Royal Commission on Environmental Pollution Scenarios

The UK’s Royal Commission on Environmental Pollution produced 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% by 2050.

The Commission investigated the various possibilities very thoroughly and summarized 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% of current consumption, consistent with the 60% reduction in fossil fuel use required to achieve a 60% cut in CO₂ emissions.

The RCEP scenarios are summarized in Box 1.4. 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 1.4 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%.

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.

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 1.55 (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)
(This figure will open in a new window)

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 1.55 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 annum – significantly faster than the historic growth rate of about 2% 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 dematerialization. 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 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 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.

The WEC scenarios, and a number of other similar studies, will be examined in more detail in the companion volume, Renewable Energy.

Meanwhile, in this volume we now turn away from this general overview to examine in more detail our current energy systems and their sustainability, starting with a look at our primary energy sources.

The T206 tour is now complete.

Enrol for T206 Energy Systems and Sustainability