New routes to compressed air storage

Enough Northwest US wind energy to power about 85,000 homes each month could be stored in porous rocks deep underground for later use, according to a new study. Researchers at the Department of Energy’s Pacific Northwest National Laboratory and Bonneville Power Administration have identified two unique methods for this energy storage approach, and two eastern Washington locations to put them into practice.

The world’s two existing compressed air energy storage plants (one in Alabama, the other in Germany) use man-made salt caverns to store excess electricity. The study examined a different approach: using natural, porous rock reservoirs that are deep underground to store renewable energy. Analysis identified two particularly promising locations in eastern Washington.

One could access a nearby natural gas pipeline, making it a good fit for a conventional compressed air energy facility. The other, however, doesn’t have easy access to natural gas. So the research team devised a hybrid facility would extract geothermal heat from deep underground to power a chiller that would cool the facility’s air compressors, making them more efficient. Geothermal energy would re-heat the air as it returns to the surface.

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