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Comment by Osiris30 | Hacker News Reader

Yeah we don't know what the actual costs will be apart from their claim that its 60% cheaper than pumped-hydro. However, having done some run-of-the-river hydro projects - even a small 1MW mini-hydro (which is basically roughly a pumped hydro in reverse) requires 2 years of civil engineering for the penstock and weir (the water channel). I would imagine that 1-10MW pumped hydro systems would cost and take a lot longer to engineer. Plus pumped hydro is very geography/topography specific.

I don't have hard data - but wouldn't engineering a rail system not be as hard, and need less civil engineering work?

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Given the mass of the cars they're talking about, they'd need substantial engineering to get a good solid level grade that's not going to subside or slip, which isn't always going to be straightforward.

As you say, however, it's very geo/topo specific - so in places like North Wales, pumped hydro is still clearly the way to go, but in the Mojave, this rail based system could work well.

It reminds me of the defunct system we had in a house I used to live in - 8" or so diameter shaft in the basement floor with a weight, a cable, a winding, and a dynamo - you'd have the servants crank it up during the day so you could have electric light at night. Quite popular in the late nineteenth century among early adopters of electricity.

Fascinating; know what that system is called?

I like this concept. I would think its all going to be about efficiency of the return power. Not a hydro engineer, but I would think that a turbine is not as efficient as a wheel tied to an electric motor. X Amount of wheel turns to store and the same X amount to restore the power. It all comes down to the efficiency of the motor vs efficiency of the generator side.

Its California / Nevada. They probably just don't have as many lakes out there that the local population is willing to convert into Pumped Hydro solutions.

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