Thursday, March 30, 2017

Storage of Renewable Energy?

Long term electrical energy stroage is still the "holy grail" for utility engineers. Lithium-ion batteries work for the short term, like overnight, but remain very expensive. Stored power from lithium-ion batteries costs between $285 and $581 a megawatt-hour, according to Lazard Ltd.  Electricity from a new gas peaker plant costs between $155 and $227 a megawatt-hour, according to Lazard.

The WSJ reports "The Golden State is ramping up renewable energy as it pledges to be a bulwark against the Trump administration’s pro-fossil fuel policies. But first, it has to figure out what to do with all the excess power it generates when the sun is shining and the wind is blowing.

California’s solar farms create so much power during daylight hours that they often drive real-time wholesale prices in the state to zero. Meanwhile, the need for electricity can spike after sunset, sometimes sending real-time prices as high as $1,000 a megawatt-hour.

California currently has to sell excess solar power at low prices or give it away to utilities in Arizona and other states, through a real-time power market run by California’s Independent System Operator, which oversees the state grid.

Sometimes, offering the excess power at low prices isn’t enough and prices go negative, as a way for power suppliers to encourage other utilities to take power they can’t use. That happened on 178 days last year.

“Storage may help you within the day, but a battery isn’t designed to store energy from March until it’s needed in June,” said Jeff Guldner, senior vice president of public policy at Arizona Public Service Co. in Phoenix."

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