4 ms·
Pretty inefficient, yes. Thermodynamics is a harsh mistress. But if the other choice is "throttle down the wind farm, because the grid doesn't need that much
by bell-cot 3y ago
Pretty inefficient, yes. Thermodynamics is a harsh mistress.
But if the other choice is "throttle down the wind farm, because the grid doesn't need that much power" - then a really cheap/simple/safe (but inefficient) storage tech could prove pretty useful.
- seanmcdirmid 3y agoHow does this compared to pumped storage?
- pfdietz 3y agoModern pumped hydro might have a RTE of 80%.
- non-chalad 3y agoYou can pump sand by bubbling compressed air through it. 1. https://www.youtube.com/watch?v=My4RA5I0FKs https://www.youtube.com/watch?v=My4RA5I0FKs
- clort 3y agoseems to me that this would result in heat-loss as the air is heated quickly then ejected from the mass. perhaps the bubbled gas doesn't hold a significant amount of heat though? (but if it did, it could be used to extract the heat without pumping the sand...)
- pfdietz 3y agoOne can get higher round trip efficiency (practically, perhaps 65%) using pumped thermal storage. Here, one uses some thermal cycle in reverse to separate "cold" and "hot", then reverse that to discharge. This also reduces the maximum temperature needed to maybe 500 C, below the creep limit for cheap steel. The cold end would be maybe -100 C, stored in something like liquid hexane.
- bell-cot 3y agoTrue. But the govt. report on this idea seems confident of 50% RTE, or 55% if they used a more-complex turbine system. For limited & short-term use, the plant with vastly-more-expensive storage masses might make sense. But as soon as you were faced with NIMBYs or environmentalists (hexane's MSDS is far closer to hydrogen fluoride's MSDS than it is to sand's), or if you are working in a less-prosperous part of the world...sand is great stuff.