Why liquid fuels or chemistry at all? Something simple like moving blocks of cement uphill with a motor/generator would be more efficient.
Why liquid fuels or chemistry at all? Something simple like moving blocks of cement uphill with a motor/generator would be more efficient.
Run the numbers and you'll find that blocks of cement are pretty expensive compared to the batteries!
Over the past decade there's been several startups trying to do gravitmetric non-hydro grid storage, and even with favorable conditions (e.g. a large free train track on the side of a mountain) they can't get the economics to work. Plus, that tech is never getting cheaper, like batteries are every day.
Do the math on energy density. 1 kg of fuel contains roughly 45 MJ, which would require you to lift 1 kg of cement 4.000 km up.
Or, alternatively, 1 liter of petrol has enough energy to lift a 3 tonne cement block 1 kilometer upwards.