3 ms·

Strange they heat the sand instead of moving it around like a pumped battery

• mikewarot 4y ago
  Moving sand (an abrasive grit) around is challenging at room temperate, doing it at 1000°F (500-600°C) seems impossible. It makes far more sense not to subject things to that kind of abrasion, and just flow air or water/steam through it.
  • pfdietz 4y ago
    It's possible. NREL's ENDURING system does just that. https://arpa-e.energy.gov/sites/default/files/2021-03/07%20Day1-Zhiwen%20Ma_NREL.pdf https://arpa-e.energy.gov/sites/default/files/2021-03/07%20D... Quick stats: stores heat in sand at 1200 C, round trip power->power efficiency of 54%, LCOS of $0.05/kWh for 100 hour storage. Heat is transferred from the sand to the gas for a Brayton cycle by direct contact in a fluidized bed heat exchanger. Babcock and Wilcox is expanding this now to the pilot stage under an exclusive license.
    • mikewarot 4y ago
      That is a very elegant work around. {They never convey the particles while hot, only after they've given up their heat, or before they get heated and then fall into hot storage} I'd be happy with 54% round trip efficiency, it's way better than losing renewable power by not being able to store it.
• nonrandomstring 4y ago
  A thermal battery is useful in concert with a heat pump.