They've got that figured out too. https://www.smartgrid.gov/project/sustainx_inc_isothermal_compressed_air_energy_storage.html
Actually it infuriates me that environmentalism is couched as a left vs right kind of thing. I work in renewable energy, and no-one should be more for distributed generation owned by homeowners than a libertarian Republican. I mean what could be more un-American and anti-free market than an electric utility granted a monopoly by the state! And the use of cap and trade to achieve lowest cost compliance is a free market success story that any conservative should love. Luckily at the state level it doesn't break on party lines so idiotically and there are plenty of conservative conservationists, they come from the same root word for peet's sake! It's just too bad at the national level the right has decided they have to reflexively be against anything that might have even a whiff of "environmentalism" to it.
That's cool, hadn't heard of their work. Looks like they're still hitting lower round trip efficiency than their biggest competitor, lithium ion and I'm a big believer in the added benefits to distributed gen and storage, but cool that they're working on this none the less.
I'm *way* with ya. Hiked the Appalachian Trail and then went to a way-leftie school and got a degree in tree-hugging. Then went to a right-wing, uber-laizzé-faire school to put numbers on it all. Solid edjumacation. Spent a career translating prospective legislation into human-speak, then into utility regulation (where I realized one day, that all the academic what-if models that I'd studied as an undergraduate, were staring me in the face, and awaiting my testimony. Yowie.) ... But yeah, I saw really good ideas be-fogged by bullshit, and more than once, fought utility White Elephants that were going to SUCK ratepayer dollars, AND DID. Hooo boy. Ewwwwww, I'm gonna stop before can't quit. Yeah -- I've been in the "environmental" game, one way or another, for almost 40 years. Phew! I'm still faithful to Uncle Milty (et.al.!!), but when poked, I still bleed green, with no contradiction.