> There was another alternative on HN recently. Basically a super-deep hole in the ground with super heavy object falling into it, but suspended by a rope.
Both are basically the same concept as pumped hydro which has been in use for a long time... pump water up a hill when energy is cheap, let it fall down and turn a turbine when energy is expensive. And hey, if it rains, free energy!
The rail/hole in the ground approach have the advantage of taking up less land I suppose, but I suspect are less efficient.
Or a train going up and down a hill...
http://www.aresnorthamerica.com/
Both are basically the same concept as pumped hydro which has been in use for a long time... pump water up a hill when energy is cheap, let it fall down and turn a turbine when energy is expensive. And hey, if it rains, free energy!
The rail/hole in the ground approach have the advantage of taking up less land I suppose, but I suspect are less efficient.