Solar and wind power are intermittent, and if enough of them are powering the grid, some kind of storage will be necessary. And storage means batteries, right?

Not necessarily. In Seabrook New Hampshire, a start-up is doing it with compressed air.

SustainX was founded in 2007 by Professor Charles Hutchinson and engineering students Dax Kepshire Th'06, '09, Ben Bollinger '04 Th'04, '08, and Troy McBride Th'01.

It’s pretty easy to see how energy stored as compressed air works: When you let go of a full balloon, it flies all around the room because of the energy stored inside. So if you use electricity to run an air compressor, you basically just need to find a way to run that compressor backwards to get electricity again.

There are places in the world that do this, one in Alabama and one in Germany, but just those two so far. That’s because they aren’t that efficient. Richard Brody is Vice President of the energy storage start-up SustainX. He says these facilities lose almost half of their energy as waste heat.

“So think of a bicycle pump, when you compress the air, it get’s warm, that’s waste heat,” Brody explains. SustainX is building a prototype of what’s basically a bicycle pump on steroids.

That means, a lot of heat. Brody says, “We’re talking about a potential change in temperature of a thousand degrees centigrade.” SustainX’s innovation is finding a way to put that waste heat to good use.