Compressed Air Storage Beats Batteries at Grid Scale CAES is efficient, scalable and familiar to utilities. Can electrochemical technologies compete in grid-scale storage?

What is the most widely deployed grid-scale energy storage technology? That would be pumped hydro, with about 21 gigawatts in the U.S. and 38 gigawatts in the EU. Pumped hydro is very site-specific, and few new pumped hydro sources have come on line in the last decade.  

Coming in second is compressed air energy storage (CAES) with a few hundred megawatts deployed across the globe at two sites — one in Alabama, the other in Germany — and a few more pilot projects in the works.

That’s pumping water up a hill and pumping air into a cave, respectively, technologies that are more Flintstones than Jetsons.

Trailing a distant third are all of the other energy storage technologies — electrochemical, thermal, gravitational and otherwise with just tens of megawatts in action — mostly in Japan as a mandated way of firming up wind power generation using sodium sulfur (NaS) batteries from NGK.

Venture firms have sunk billions into battery, fuel cell and flow battery startups with utility-scale grid storage seen as the holy grail that turns variable energy sources like wind and solar into firm dispatchable power like coal or natural gas-fired plants. ARPA-E and the DODare funding advanced technologies for energy storage, as well.

But there are a few problems with the electrochemical solutions — starting with cost, long-term reliability and utility familiarity.  Lithium-ion batteries might be good for cells phones andelectric vehicles, but when it’s time for hundreds of megawatts — that leaves CAES.