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...or gravimetric pump batteries to store energy which don't rely on complex high-temp furnaces to be maintained... nah that'd be daft
by rob_c 5y ago
...or gravimetric pump batteries to store energy which don't rely on complex high-temp furnaces to be maintained... nah that'd be daft
- jacquesm 5y agoThere are parties trying that as well, both by pumping 'uphill' as well as by using underground storage, there are also parties that are trying to do this with moving weights (but I don't think that will come to anything at scale).
- ncmncm 5y agoYeah, the cranes and weights thing is the dumbest idea I have encountered lately. Using deep underground cavities to drain water into, and pump back out of, extends pumped hydro to a lot more places than are usually assumed suitable. And, it multiplies the energy stored up a hill if you can drain the water to somewhere deep. The most surprising method I have enountered is deep-ocean pumped storage. This doesn't need a pipe, just a tank anchored down deep with a pump/turbine at the bottom. You charge it by pumping the water out, leaving water vapor, and get the energy back by letting the water back in. The only connection to shore is the wire. The amount of energy you can store in a 30-meter diameter tank under 300m of water is amazingly large. The tank does need to be very strong to hold back the pressure.
- jacquesm 5y agoYou could use two different fluids with different densities, lose a bit on the efficiency but far lighter construction.
- ncmncm 5y agoCan't see how that could work.
- jacquesm 5y agoThere are car suspension systems that use this principle and they work well. The same principle applied here: heavier fluid and the lighter one are separated by a membrane, you pump the lighter one in under pressure to force the heavier one out and the heavier one will descend by itself and force the lighter one out due to gravity. Efficiency will be impacted by the ratio between the lighter one and the heavier one. Ideally the lighter one would be a gas but at those pressures that may no longer work.
- ncmncm 5y agoI could see this with a pipe down to deep under water. You pump in air pushing water out the bottom; and let the air out through a turbine to extract power. And, with a big tank or bladder at the end, to keep the pressure nearly constant. Or, deep under the water table, and no tank or bladder needed because there is a big cavern down there. I suppose this could work with a lightweight, immiscible liquid, instead... A pipe down to a closed bladder, and pumping water in, would be simpler.
- ncmncm 5y agoer, air in. Or, I guess, oil? But oil masses 7/8 as much as water. Air gets denser as pressure rises.