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Unless there is big improvements in battery tech I don't see it as a solution. Lithium batteries have their own environmental problems and die after 10 years.

Unless there is big improvements in battery tech I don't see it as a solution. Lithium batteries have their own environmental problems and die after 10 years. Pumped hydro requires the geography, building new capacity tends to flood large areas and release huge amounts of greenhouse gases initially. Simply lifting weights on cranes or rail tracks is looking more efficient and can be adapted anywhere. It will probably win out in many cases.

usrusr 8y ago
> Simply lifting weights on cranes or rail tracks is looking more efficient and can be adapted anywhere. The energy density of that kind of scheme is a joke. Thought experiment: a fully charged Tesla, how often could it climb a hill the size of that crane if it skips recuperation on the downhill leg? That's how much lower the energy density of a crane storage would be. Pumped storage works (where the geography allows it) because water is by far the cheapest and the most easily transported ballast and geographic height differences dwarf almost every human made structure. If you want something that scales everywhere, look no further than compressed air. It's usually ignored because of the big thermal losses, but if you have a direct application for coolant they are not that bad and even without, it serves as an almost trivial lower bound to the storage problem. We can calculate how much intermittent energy production we would need with compressed air to serve a power demand profile and everything else is just a possible improvement.
- ShorsHammer 8y ago
  Since when was energy density ever been a problem for grid storage? Even in the most crowded cities on earth it's not a constraint. Unless you are talking about portable applications it's all about round trip efficiency and cost, I'm not sure if you are getting confused about terms here or talking about an entirely different subject. Compressed air efficiency isn't great. Using it for cooling lowers the efficiency even more. Crane and rail gravity storage are pushing 80-90% round trip efficiency. Previous HN discussion: https://news.ycombinator.com/item?id=17789456 https://news.ycombinator.com/item?id=17789456

usrusr 8y ago

> Simply lifting weights on cranes or rail tracks is looking more efficient and can be adapted anywhere. The energy density of that kind of scheme is a joke. Thought experiment: a fully charged Tesla, how often could it climb a hill the size of that crane if it skips recuperation on the downhill leg? That's how much lower the energy density of a crane storage would be. Pumped storage works (where the geography allows it) because water is by far the cheapest and the most easily transported ballast and geographic height differences dwarf almost every human made structure. If you want something that scales everywhere, look no further than compressed air. It's usually ignored because of the big thermal losses, but if you have a direct application for coolant they are not that bad and even without, it serves as an almost trivial lower bound to the storage problem. We can calculate how much intermittent energy production we would need with compressed air to serve a power demand profile and everything else is just a possible improvement.

ShorsHammer 8y ago
Since when was energy density ever been a problem for grid storage? Even in the most crowded cities on earth it's not a constraint. Unless you are talking about portable applications it's all about round trip efficiency and cost, I'm not sure if you are getting confused about terms here or talking about an entirely different subject. Compressed air efficiency isn't great. Using it for cooling lowers the efficiency even more. Crane and rail gravity storage are pushing 80-90% round trip efficiency. Previous HN discussion: https://news.ycombinator.com/item?id=17789456 https://news.ycombinator.com/item?id=17789456