Startup SustainX brings a big next-gen air battery online

Startup SustainX has turned on its first large air energy storage device, which stores energy like a battery does but in the form of compressed air in tanks. The company, which has raised funding from investors like GE(S ge), RockPort Capital, Polaris Venture Partners and the Department of Energy, said the device is the world’s first megawatt-scale (1.6 MW) isothermal compressed air energy storage hardware. Startup General Compression has also commissioned a 2 MW scale project using similar air storage technology.

While air energy storage tech is decades old, there’s a new generation of startups working on new innovations with this technology. SustainX had already built out a 40 kilowatt air energy storage project at its headquarters in West Lebanon, New Hampshire, and other startups like General Compression and LightSail are working on similar tech. But reaching the megawatt-scale — there are 1,000 kilowatts in 1 megawatt — is important because it shows that the technology is getting closer to reaching commercial scale.

SustainXThe idea behind the new compressed air energy storage tech is that utilities and power companies will install the compressed air energy storage devices next to power generation plants –both fossil fuel-based power sources like coal and natural gas, and clean power farms like wind and solar. The compressed air energy storage tanks use excess energy to compress air and store it until energy needs to be delivered;  to deliver the energy the tanks release the air, which runs turbines, and in turn creates electricity.

Compressed air energy storage could be particularly useful for clean power generation, because wind only generates electricity when the wind blows and solar only provides power when the sun shines. But paired with energy storage, solar and wind farms could provide energy when the wind stops blowing and the sun stops shining.

There are a variety of forms of utility-scale energy storage, from banks of lithium ion batteries, to large pumped hydro energy storage installations (pump water up a hill and let it flow back down), to wacky stuff like these gravel buckets on a ski lift. Each of the forms have different costs and benefits.

Compressed air energy storage is thought to be one of the more inexpensive forms of utility energy storage, particularly compared to tech like lithium ion batteries. The key to the air energy storage is to make the compression and release of the air as efficient as possible. Several of these startups are using a water spray in the air to manage the temperature of the compression and release. Other researchers are looking at ways to compress air into underground chambers instead of tanks.

Investors and venture capitalists have seemed interested in investing in innovation around compressed air energy storage. LightSail is backed by Khosla Ventures, Peter Thiel and Bill Gates. General Compression is funded by US Renewables Group, ConocoPhillips, Duke Energy, Serious Change, and the Wellford Energy Group.

SustainX expects that its first commercial units will be installed in China next year, according to IEEE Spectrum. LightSail and General Compression are working on similar time lines.

Updated on September 24 at 11:42AM PST to add in information about General Compression’s 2 MW project.