Using compressed air as green energy storage Mar 15 2013
LightSail Energy, headed up by 25-year-old Danielle Fong, is developing technology to store energy as compressed air.
A stumbling block to increasing our reliance on electricity from cleaner energy sources such as solar panels and wind farms has always been figuring out how to efficiently store the energy for use when the wind isn't blowing and the sun isn't shining. Danielle Fong could make clean energy significantly more practical on a large scale by introducing a novel way to use tanks of compressed air for energy storage. "It could radically reorient the economics of renewable energy," she says.
The idea of using compressed air to store energy is not new. Electricity from solar panels or wind turbines can turn a motor that's used to compress the air in a large tank, and the air pressure can then be converted into power to drive a generator when the power is needed. The problem is that during compression the air reaches temperatures of almost 1,000 ^0C. That means energy is lost in the form of heat, and storage in conventional steel vessels becomes impractical.
Fong stumbled on a possible solution while skimming through a nearly century-old book: water spray is great at cooling air. She asked, why not spray water into the air while compressing it, so that the air stays cool? To make the process practical, she developed a technique for separating the heated water from the compressed air and diverting the water into a tank, so the heat can be recaptured to minimize energy loss. The process is about as efficient as the best batteries: for every 10 kilowatt-hours of electricity that goes into the system, seven kilowatt-hours can be used when needed.
Fong sounds like an impressive person; she dropped out of middle school at 12 to attend college, graduating five years later with degrees in physics and computer science.