Battery breakthrough

A big battery breakthrough is under way which could provide a big boost for renewables. The world’s biggest and fastest battery has been switched on in Texas.

It’s huge, capable of handling 36 MW of windpower, for Duke Energy’s Nortrees wind farm. The wind farm itself is rated at 153 MW.

The challenge for just about all renewables is to smooth the supply to consumers – to find a way of keeping up output when the wind doesn’t blow or the sun doesn’t shine, or when there’s a sudden big rush of demand.

Over a big grid system, the balance is kept by switching on additional power plants. But this means cost and duplication, and there is also a delay in response: it takes about 15 minutes to get a natural gas power plant output on line.

The alternative of storage of power is already used with hydro-electric schemes, where water is pumped uphill at times of surplus power, to be let loose again to drive the turbines when there’s a shortfall.

But, as the magazine New Scientist reports, the battery designs have been steadily developing. The company Xtreme Power that built the Texas battery has been steadily building up, with its products in use with wind farms in Hawaii and Alaska as well, and it’s using lead-acid battery modules the size of a bus.

In the Californian city of Modesto a company is installing a 25 MW zinc-chloride flow battery, where a liquid electrolyte circulates. This battery will replace a planned 50 MW fossil fuel plant. Elsewhere in California the Pacific Gas and Electricity Company is going to fill depleted gas wells with compressed air, in a 300MW system.

Meanwhile the researchers are pressing forward to seek new designs, hunting for new options for electrodes and electrolytes. A report in The Economist describes how Argonne National laboratory has been given a challenge by the US Department of Energy – to make batteries five times more powerful and five times as cheap in five years. The challenge has been backed up with a grant of $120 million. To speed their work, Argonne will draw on a big materials reference library that’s being built up at MIT.

Some researchers are seeking to improve the lithium-ion batteries of today; others are looking into new options, such as lithium-air or the use of magnesium or aluminium, which have more free electrons to react chemically.

The battery breakthrough is coming about as the result of a careful strategy by the US Department of Energy, under Energy Secretary Steven Chu, physicist and Nobel Laureate. He’s now announced that he’s stepping down to return to his academic research, but he leaves behind him a series of major developments, from the growth of renewables projects to energy-saving improvements for low-income homes.

The New Scientist highlights the scale of the change that’s come about through initiatives by the federal government and the various states and cities themselves. It quotes a report by a think-tank, resources for the Future, which predicts that the US is on course to meet President Obama’s 2009 pledge to cut emissions by 17 per cent, from 2005 levels, by 2020.

True, some of the cutback in emissions has come from the boom of cheap natural gas which emits much less carbon dioxide than coal. And true, the momentum from the individual states is noticeable, with California having at the start of this year launched its own carbon cap-and-trade system, aimed at cutting its emissions to 1990 levels by 2020. But there is no doubt that the technology is moving forward fast and opening the way for new industries and new job opportunities to emerge.

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