However, air may yet hold the key to energy storage – in liquid form. For the past two years, on a patch of land not much bigger than a basketball court in Slough, UK, a liquid air pilot storage plant has been quietly generating electricity using the excess energy from a neighbouring biomass plant. This tangle of gleaming white pipes and tanks has enough advantages over rival technologies to have been hailed as a critical part of our energy future. “This could save the UK billions,” says Tim Fox, head of energy and environment at the Institution of Mechanical Engineers in London.

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