STORING WIND IN A HOLE IN THE GROUND

Study: How Northwest Wind Can Play With Energy Storage And Provide Operational Flexibility

Frances White and Joel Scruggs, 23 May 2013 (North American Windpower)

“Enough Northwest wind energy to power about 85,000 homes each month could be stored in porous rocks deep underground for later use [using two unique methods], according to a new, comprehensive study..[by researchers] at the Department of Energy's Pacific Northwest National Laboratory (PNNL) and Bonneville Power Administration (BPA)…[About 13%, or nearly 8.6 GW, of the Northwest's power supply comes from wind]…

“Compressed air energy storage plants could help save the region's abundant wind power - which is often produced at night when winds are strong and energy demand is low - for later, when demand is high and power supplies are more strained. These plants can also switch between energy storage and power generation within minutes, providing flexibility to balance the region's highly variable wind energy generation throughout the day…”

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“All compressed-air energy-storage plants work under the same basic premise. When power is abundant, it is drawn from the electric grid and used to power a large air compressor, which pushes pressurized air into an underground geologic storage structure. Later, when power demand is high, the stored air is released back up to the surface, where it is heated and rushed through turbines to generate electricity. Compressed-air energy-storage plants can regenerate as much as 80% of the electricity they take in…

“The world's two existing compressed-air energy-storage plants…use man-made salt caverns to store excess electricity. The PNNL-BPA study examined…using natural, porous rock reservoirs that are deep underground to store renewable energy…Analysis identified two particularly promising locations in eastern Washington…The Columbia Hills Site could access a nearby natural gas pipeline, making it a good fit for a conventional compressed-air energy-storage facility…The Yakima Minerals Site, however, does not have easy access to natural gas. So…[it] would extract geothermal heat from deep underground…”

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