A Sustainable Future? The limits to Renewables

Although vast quantities of energy arrive daily from the sun, capturing it is always going to be limited by technical, ecological and land-use constraints. The most serious barrier to capturing it at present, however, is that other energy sources are artificially cheap. Can renewable energy save the world from climate change by replacing fossil fuels? It is relatively easy to outline a series of 'technical fixes' for the climate change problem which would allow most of us to continue to live much as at present, at least for a while. Shell's 1995 scenario1 suggested that, in theory, renewables could be supplying possibly 50% of world energy by 2050 and, in 1993, the Stockholm Institute's scenario for Greenpeace suggested that, if we wanted to, we could have a world system based almost entirely on renewables by 2100, even assuming continued growth at 2% a year in energy use.2 Since these studies emerged, renewables have developed rapidly - for example, there is now 24,000MW of wind power in use around the world - and it has been argued by Amory Lovins that demand for energy can be dramatically reduced by clever 'Factor 4' and even 'Factor 10' energy efficiency measures3. So the prospects for a shift to a sustainable future are looking promising. Indeed, there is something of an emerging consensus that, as the UN/World Energy Council 'World Energy Assessment' report, published in 2000, put it "there are no fundamental technological, economic or resource limits constraining the world from enjoying the benefits of both high levels of energy services and a better environment". A little more cautiously, the report adds "A prosperous, equitable and environmentally sustainable world is within our reach, but only if governments adopt new policies to encourage the delivery of energy services in cleaner and more efficient ways"4 However, the consensus is not complete. Although renewables are seen as playing a rapidly increasing role in this optimistic future, the strategy that is seen as being required also relies on continued use of fossil fuels, albeit more efficiently, and possibly also on the expanded use of nuclear power. Most environmentalists cannot countenance the latter option: they argue that, quite apart from the uncertain economics, why try to solve one problem (climate change) by creating another (radioactive pollution)? In addition, there is the possibility, argued forcefully by Colin Campbell and others, that the economically extractable reserves of oil and gas, may not be sufficient for their continued use on a large scale for very long. If that is so, we will have to move even faster to renewables. Certainly, the WEA's fairly leisurely approach to replacing fossil fuels with renewables may not be adequate in the face of the climate change threat. We may not simply be able to wait for fossil fuels to run out (or rather to become prohibitively expensive). Sheikh Yamani is alleged to be the original source of the now familiar view that 'just as the Stone Age didn't end because people ran out of stones, the Oil Age won't end because we run out of oil.' So there are plenty of reasons why we should consider moving rapidly to a more sustainable approach, based on the use of renewable resources and the adoption of more efficient ways of using energy. That will not be easy. The development of the new green energy systems involves many technical challenges, and many believe that it will in practice be difficult to actually achieve major energy efficiency gains. In addition, there are many strategic and political battles to be won - for example, that to obtain the necessary funding. However, in this paper I will try to explore the basic resource problems that face this approach. For not everyone believes that there will be sufficient renewables energy resources to meet growing demand, especially as the developing countries industrialise