Even the best lithium-ion batteries stink at storing the large amounts of electricity a massive wind or solar installation is capable of generating. They’re expensive and hold, at most, about four hours’ worth of that grid-scale juice. Here are five potentially less costly—if somewhat Rube Goldberg-y—methods companies are trying to store power as potential energy in other forms, smoothing out renewable energy’s peaks and valleys.
Compressed Air
Hydrostor Inc. in Toronto expends grid power to compress air, which it pumps underground for storage, with a column of water keeping it compressed. Abating the pressure allows the air to decompress, releasing its energy to drive turbines on the surface for 24 hours or more. Hydrostor has two demo plants in Canada and others slated for development in the U.S., Chile, and Australia. Chief Executive Officer Curtis VanWalleghem says Hydrostor has raised $30 million and expects to double that this year.
Liquid Air
London’s Highview Power feeds wind- and solar-generated electricity into a set of off-the-shelf components that liquefy air by cooling it. To send power back into the grid, Highview heats the liquid, expanding it to drive turbines that generate electricity for at least 12 hours. CEO Javier Cavada says the company has raised about $50 million; it’s built two small-scale plants in the U.K. and is finalizing a deal for a commercial plant in the U.S.
Mine Shafts
Edinburgh’s Gravitricity Ltd. stores gravitational energy by using power from renewables to lift a weight of as much as 3,000 tons in a mine shaft. Letting the weight fall releases the energy, generating enough electricity to deliver power for as much as eight hours. The system’s winches and cables have a working life of 50 years or more, says Managing Director Charlie Blair. The company, which has raised about $1.7 million from the U.K. government and private investors, is at work on a 50-ton demo.
Recent Comments