The Pacific Northwest has abundant renewable energy resources, being the home to one of the largest networks of hydroelectric dams in the U.S. But state mandates for renewables on the grid have driven a boom in wind installations, which has actually led to a problem. The Bonneville Power Administration has forced wind farm owners to curtail their output of power at times of limited demand on the grid.
This occasional glut of power has led the Federal Energy Regulatory Commission to ask the BPA to find a way to handle oversupply that does not punish wind farm owners.
A new study by the Electric Power Research Institute proposes utilizing compressed air energy storage, or CAES, to store the excess power generated. The electricity is used to compress air and pump it into underground reservoirs. When it is needed, the air is uncorked, heated up, and used to run turbine generators.
There are already a few commercial CAES sites that can store the air in tank-like salt caverns. The Washington State study focuses on a couple of subterranean basalt reservoirs. Estimates are that these porous volcanic rock basins could store enough energy to power roughly 85,000 homes. These rock formations are far below the water table – places similar to where oil and gas reserves are found.
Using compressed air could store excess electricity for hours or even for months. With seasonal changes, the Northwest’s renewable resources are variable and the ability to store energy when it is plentiful represents a significant advance.
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Too Much Wind Energy? Save It Underground in Volcanic Rock Reservoirs
Photo, taken on August 13, 2009, courtesy of CGP Grey (http://www.cgpgrey.com) via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.