The latest effort to store clean power from wind and solar energy resources comes from California, where a leading utility is hoping to put emerging technology to work.
A report in the San Francisco Chronicle describes how Pacific Gas and Electric is working on a facility that would transform the energy from clean power resources into compressed air that would be stored in underground porous rock and then used later to power turbines.
The utility has reportedly applied for a $25 million federal grant to develop the technology, which has also been tested in places, such as Alabama and Germany. According to the newspaper, the utility envisions using windmills to produce about 300 megawatts of energy for as long as 10 hours during nighttime hours when wind levels are at their strongest. During daylight hours or during any lull in wind activity, the stored compressed air could be tapped for supplemental power.
As noted in the story, because the system relies on a naturally occurring geological phenomenon, location is a factor:
If it proves economical, it could be replicated anyplace with appropriate rock formations underground as well as strong sunlight or strong wind.
“You need the right geology, but it’s not a really rare geology,” said PG&E spokesman Jonathan Marshall. “If we can move this forward, it can be done around the country.”
Some solar thermal facilities in California and elsewhere also use molten salt to maintain heat levels and keep turbines running, in off peak-production hours.
By increasing the storage capacity and time for solar energy and wind power, it will resolve one issue that the industry has long been working to improve upon.