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Tilting at windmills - 100% renewable energy

Greenpeace has published the latest in a bi-annual series of studies focussed on energy, written jointly with the Global Wind Energy Council and SolarPowerEurope. This year’s Energy [r]evolutionis a particularly important one because of the impending Paris climate summit, on which so many hopes are riding. The big message this time around is that it is possible to deliver a global energy system which is 100% renewable by 2050 (see Is a 100 per cent renewables-powered world really possible?).

The study is certainly well produced and weighty – coming in at 364 pages – but not all of this is taken up by arguments based on evidence, unfortunately. Although we should always be open-minded, the authors clearly, and hardly surprisingly, have an agenda. Billed as an alternative to the regular reports issued by the International Energy Agency (World Energy Outlook 2015is due out in November) the study makes a strong case for its own preferred vision, but says little about how it might be achieved.

Energy [r]evolution essentially sets out three scenarios: business as usual, 80% renewable energy by 2050 and 100% renewable energy by 2050. It is the first time in the ten years of publication that the most radical, all renewables, scenario has been put forward.

On the breakdown of the energy market and the evolution of renewables the authors present a factual picture, but enthusiasm for renewables has tended to blur the facts. For example, we read that “between 2005 and the end of 2014 over 496,000 MW of new solar and wind power plants have been installed – equal to the total capacity of all coal and gas power plants in Europe!”

Taken together with an additional 286,000 MW of hydro, biomass, concentrated solar (strangely, not included alongside photovoltaics) and geothermal power plants, this makes “783,000 MW of new renewable power generation connected to the grid in the past decade – enough to supply the current electricity demand of India and Africa combined.”

As most people should already know, all electricity generating systems are not created equal. An installed megawatt of capacity from a coal, gas or nuclear station can be relied upon to provide that whenever needed, bar scheduled maintenance. An installed megawatt of wind capacity will only produce perhaps 30% of its rated output, and then not necessarily when there is demand. Solar is even worse, with an average capacity factor in northern Europe of only about 10%.

So, that nearly 500 GW of wind and solar capacity is probably equivalent to only about 150 GW over the whole year. And, more importantly, it is unlikely that a single coal- or gas-fired station was closed because of this new capacity, since backup of up to essentially the full nominal output would be needed at times.

This vision of radical and rapid decarbonisation is put forward on the understanding from the most recent IPCC synthesis report that we have already emitted fully two-thirds of the amount of greenhouse gas deemed to represent a ‘safe’ level which would be likely to limit average temperature rise to 2°C above pre-industrial levels. At projected rates of fossil fuel use, the ‘safe’ limit would be exceeded by 2040. Hence the urgency.

This is a perfectly legitimate position to take, although others would suggest that the situation is less urgent and that, in any case, we do not have the technology to make a real difference at present. Under these circumstances, you would expect that nuclear would be seized on by Greenpeace as offering the best chance of decarbonising the electricity generating system while maintaining energy security.

Unfortunately, this is not so. Having campaigned against nuclear power for many years, Greenpeace is not prepared to change its policy in face of an even bigger challenge. In this, they differ from many other committed environmentalists. They dismiss the technology for a range of reasons, including the usual concerns about safety, nuclear waste and nuclear weapon proliferation, but also the fact that nuclear cannot make a contribution to emissions reduction before 2020. To dismiss the best available – and, despite their assertions, safe – low-carbon generating technology in this way is a major flaw in the argument and makes achievement of the highly ambitious goals almost impossible.

The study recognises some of the challenges to be overcome. Currently we are dealing with the difficulties of reducing emissions from electricity generation, but that is the easy one. Heating (and/or cooling) uses at least as much energy in many parts of the world, and for this more radical solutions have to be found to replace gas and oil. The best way forward – as the study points out – is to build much more energy-efficient houses and offices. But this is a long-term programme and there are limited options for retro-fitting older houses. Heat pumps are a great idea in principle, but very costly to install and best done for new build.

Even more challenging is transport. The study reports that the number of electric vehicles worldwide doubled to 665,000 over the year. This, however, is somewhat misleading, being taken up mainly by plug-in hybrids. This is clever technology and very appropriate for urban driving, but these are not electric vehicles in the true sense of the word. Converting the car fleet to fully-electric cars would be the work of many decades, and a true fully-electric alternative to the conventional engine is not going to be available for some time to come. Despite the hype, it is unlikely that even the present VW diesel engine emissions scandal will do much to boost the sale of plug-in hybrids or fully electric cars.

If and when electric road vehicles become mainstream, massive investment will be needed in more power generation and distribution systems. A fully renewable generation network would be no better able to cope with this than with current demands (actually, arguably worse: failure would hit transport as well as domestic and industrial use). Neither are biofuels the answer: their benefits are often overstated and there is simply too little potential volume to supply more than a fraction of the market. In any case, they would be needed to fuel planes and ships, which realistically cannot be used without liquid fuel.

The report talks about the need to address the challenges and develop generating, storage, heating and cooling technologies, but gives no real examples of how this could be done. Working through scenarios on the assumption that the right technology exists is all very well, but they would be much more credible if potential solutions to the many existing problems had been put forward. Maybe innovations in coming decades will make more widespread use of renewables a viable and economic option. Until then, the energy [r]evolution remains a dream.

Martin Livermore

The Scientific Alliance

St John’s Innovation Centre

Cowley Road

Cambridge CB4 OWS