Danielle Fong focuses on low cost energy storage, but she's not developing batteries. Her work takes advantage of the low cost of wind and solar energy and seeks to make the energy more usable through compressed air storage.
In her Solve for X talk, Economically Storing Energy as Compressed Air, Fong discusses her work and showcases some of the big advantages of her ideas. Wind and solar power costs are going down, she tells us, and compressed air is already very inexpensive. She was flipping through an old book and found that water spray is great at cooling air - this led her to the idea of using water to aid in the compression of air.
In the field compressed air equipment lasts between twenty and thirty years. Efficiency has been the problem with compressed air, because of the large amounts of heat generated when compression occurs. Higher heat requires a higher pressure for storage.
Fong developed a method to keep the air cool while compressing and warm while expanding. She heats water using solar or wind energy and then sprays that warm water into the air. The water is diverted into a tank and the heart energy is recaptured. For every ten kilowatt-hours of electricity entering the system, seven kilowatt-hours can be used when needed.
Water compression has already doubled the efficiency of compressed air storage and is expected to push farther. Danielle presents what she calls her Trillion Dollar Formula: Offpeak Energy + Energy Storage < Peakers + Grid Upgrades.
Fong was one of the MIT Technology Review's TR35 in 2012 - this talk was filmed in late 2012 and the work is still moving forward. In late 2013 she was showcased as one of CNN's 40 Under 40 technologists, and one of Time's 30 People Under 30 Changing the World. A few places online give Danielle credit for being a 21st century steampunk, using 12th century technology to store power.
Her company LightSail Energy was initially started to build air-powered scooters but she quickly moved on to a much bigger scale. Her current work focuses on a proprietary material for building storage tanks that will work more efficiently and cheaper than steel tanks.