Underground caverns may have never been seen as energy containers, but a Utah-based private equity group promises to use them filled with compressed air to generate electricity the classic way – by spinning a turbine.
The desert patch from Utah hides a massive salt deposit a mile underground that the company will use to store the energy and create a giant subterranean battery.
Energy storage is useful for the grid because it can act as a buffer for those times of excessive consumption, when the power plants just can’t deliver what they’re asked. They are also good at storing the energy coming from intermittent alternative sources, such as wind or solar power. Jim Ferland, senior vice president for operations for PNM Resources said: “the wind doesn’t always blow; cloud cover can shut down solar cells – that utilities can take only so much of it”.
A similar project already exists and works in McIntosh, Alabama, and Bremen, Germany, with ongoing development for others in Norton, Ohio, and Ankeny, Iowa.
At first, Salt Lake City-based Magnum Energy LLC is going to deposit natural gas for Rocky Mountain producers in the cavern it is planning to start within a year, and take it from a nearby interstate pipeline. The “energy hub” is going to be located near Delta, Utah.
After developing the natural gas project, they plan to dig other caverns for the compressed air, storing the extra power produced by a neighboring wind farm, and then release the air (and produce electricity) when needed – acting as a buffer for the grid.
The compressed air cavern could also store carbon dioxide from coal factories. In that case, re-releasing it in the atmosphere would definitely be a problem, but recirculating it with the help of wind power, the CO2’s pressure might actually do some good for the environment.
“In terms of storing bulk energy – lots of megawatt-hours – compressed air is cheaper than anything else out there,” said Paul Denholm, lead analyst for energy storage at the U.S. Department of Energy’s National Renewable Energy Lab in Boulder, Colo.
Other approaches towards storing excess energy imply spinning wheels at high speeds and using molten salt batteries, but they’re pretty expensive and thus hard to implement at a higher scale. In the meanwhile, underground caverns offer a simple, mechanical solution that might just work for everybody.