The US National Renewable Energy Laboratory was working on energy storage involving a silo of hot sand.[1] But that was probably cut by the Trump Administration

The US National Renewable Energy Laboratory was working on energy storage involving a silo of hot sand.[1] But that was probably cut by the Trump Administration.[2] The sand scheme involves putting hot sand into the top of the silo, and draining out sand into a heat exchanger at the bottom. So you can have more storage than you have heat exchanger capacity. The "ultra cheap" approach in the article requires resistance heaters and plumbing all through the cheap dirt. Molten salt has also been used for this, successfully. [1] https://www.solarpaces.org/nrel-results-support-cheap-long-duration-energy-storage-in-hot-sand/ https://www.solarpaces.org/nrel-results-support-cheap-long-d... [2] https://www.wenatcheeworld.com/news/northwest/trump-congressional-republicans-propose-big-cuts-for-western-renewable-energy-labs/article_9fe5ce72-377d-4029-b9b4-2ca5d71108e8.html https://www.wenatcheeworld.com/news/northwest/trump-congress...