Low-carbon grids need longer-duration storage, but few technologies have succeeded at scale. Here’s the current roster of best bets.
https://www.greentechmedia.com/articles/read/most-promising-long-duration-storage-technologies-left-standing
* in the U.S. * other developed countries * 95 percent of U.S. grid storage * 400-megawatt Gordon Butte * backing from NextEra Energy * $110 million from SoftBank * signed up * raised $46 million * stored power in underground caverns * tried and failed * different approach * raised another $37 million * raised another $30 million * renting vanadium from mining companies * soon take over U.K. flow company RedT