Source: Conservation Magazine
In the battle to scale up intermittent energy sources such as wind and solar, the team with the best storage strategy wins. While many companies are banking on new battery technologies to fill the gaps when the wind dies and the sun sets, a few are working on storing energy using a cheap, abundant resource—the very air around us.
Compressed air energy storage, or CAES, is elegant and simple in concept: use excess power from the electricity grid to compress some air, then let it expand and turn a turbine when you need the electricity back. “It’s a pretty simple idea,” says Steve Crane, the CEO of LightSail Energy, one company refining compressed air technology with the hope of making a dent in the storage market soon. “Like a lot of simple ideas, it is easy to describe, and it is fiendishly difficult to actually implement.”
It’s an idea long touted as a transformative energy-storage method. But early attempts at CAES have been held back in part by those pesky laws of thermodynamics: compressing air into a tighter space than it would prefer generates heat—a lot of heat. The heat losses translate into low efficiency—you need to put a lot of energy in to get just a bit of energy out, with the rest lost as heat.
To deal with the heat, technologies from new companies including LightSail, SustainX, and General Compression keep the compressing air at a near-constant temperature with the simple addition of a fine water mist. Water heats up far more slowly than air; instead of an increase of around 1,000 degrees Celsius with just air, the temperature may go up by only 40 degrees or so. And with that, CAES is no longer too hot to handle.