Energy storage gets second wind

The Engineer

Few topics polarise the opinion of UK armchair energy analysts more than wind energy. To its champions, it will become an ever more vital component of our energy mix over the coming decade, making up much of the shortfall as up to a quarter of our existing generating capacity comes offline. To its detractors, it is an expensive, inefficient technology that is overly reliant on subsidies and so unpredictable that it is impossible to deal with.

While the extreme ends of both arguments should be treated with scepticism, there is certainly no disputing the fact that when the wind stops blowing, turbines stop generating.

With wind currently forming a relatively low proportion of total demand, intermittency isn’t a major problem yet. But if, as the energy industry and the government hope, this proportion rises, it will become more of a headache.

According to industry trade body RenewableUK, an average wind turbine will, over the course of a year, generate 20-30 per cent of its theoretical maximum output. Some claim this figure is overoptimistic. A recent report published by wildlife charity the John Muir Trust and based on National Grid wind data concluded that for a third of the time 2010 wind output was less than 10 per cent of capacity. Compare this with coal, gas, or indeed nuclear, where availability assumptions creep towards 100 per cent and it is easy to see why many, including National Grid’s research chief Ian Welch – interviewed here – believe that how we deal with the intermittency issue will have a profound impact on the UK’s future energy landscape.

One potential solution is explored in our latest Big Story which looks at intriguing technology that could enable energy companies to effectively save wind energy for later.

The idea behind compressed air energy storage (CAES) is elegantly simple: when the wind blows, turbines are used to compress air, which is stored in pressure vessels. In times of high demand, this pressurised air is released and used to power an electricity generator.

The concept has been around for a while but until recently the heat lost during the compression process made it inefficient. With researchers now nibbling away at these inefficiencies, CAES is now looking like an increasingly compelling technology, and could one day be just the kind of energy storage system that Welch and his National Grid colleagues dream about.

On a different note, The Engineer Technology and Innovation Awards 2011 are now open for entries. If you’re involved in a technology-led collaborative project with a commercial or academic partner and believe your work could have a major impact in its field visit our awards website before 15th July for a chance to join other finalists at the Royal Socety in London on 2 December