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The easiest way to squirrel away electricity in times of plenty, for use when it is scarce, is to pump water uphill with it. Such pumped storage is widely employed where local geography and hydrology permit, but it does need two basins, at different heights, to act as reservoirs, and a supply of water to fill them.
[...] Where geography does not favour pumped storage, though, the search is on for alternatives. These range from giant batteries, via caverns filled with compressed air, to huge flywheels made of carbon-fibre composites. But one firm looking into the matter eschews all these. It has stuck with the logic of pumped storage, which is to move large amounts of matter up and down hills. The difference is that in its case the matter is solid.
The firm in question calls itself ARES, which stands for Advanced Rail Energy Storage.
[...] The rocks stand in for the water in a pumped-storage system. They are carried up- and downhill by a train that is thus the equivalent of the turbines. The track the train runs on is equivalent to the tunnel. And the motors that drive the train act, like the electrical kit of a pumped-storage turbine, as generators when they run in reverse as the train rolls backwards downhill, pulled by gravity.
(Score: 3, Interesting) by bob_super on Saturday December 03 2016, @06:54PM
That's a pretty dumb idea, really, if you consider the footprint vs energy. In the US SouthWest, where there are lots of space and hills, it might make sense. Elsewhere, not so much.
The numbers are in TFA (sorry): This thing gets you peak 50MW for at most 15 minutes, using a 9km footprint and cable set. To get to that number, you need a pretty heavy train, so you need some seriously strong tracks.
But you ain't doing much with 50MW, unless you're looking at wind turbines very gradually slowing down. The gas plant you need to fire up before you reach the bottom of the track will output a whole lot more, so need quite a few trains to keep a constant supply.
Pumping water up (where you do have water) scales a whole lot better, and you occasionally get free energy. Pumping mercury would be fun and more energy storage per m^3.
I read somewhere about a much much better concept: Essentially a giant concrete/rock elevator (or lead, depleted U, gold, rusted iron...). Fits inside a city, even a flat one. Allows the motor/generator and power cabling to be fixed, and only requires a building-size crazy-strong foundation. Might take as much metal as the train, but is a lot more practical to maintain.
(Score: 0) by Anonymous Coward on Saturday December 03 2016, @08:15PM
> Pumping water up (where you do have water) scales a whole lot better, and you occasionally get free energy
There is no water in the desert.
> I read somewhere about a much much better concept:
Sounds conveniently undetailed.
(Score: 2) by frojack on Saturday December 03 2016, @08:20PM
You can't condemn the concept by the limitations of the demonstrator project.
They plan to elevate many more weights than would be used in a single downhill run, they warehouse these at the top, and move them to the downhill run as needed, potentially supplying a many hours of electricity generation.
As for the tracks, once the roadbed it built, you simply add more rails and wheel trucks. You are not limited to two rails.
You won't be building this on swampy ground, so the weight bearing issue as manageable. People with lesser technology have been doing this kind of moving since the Pyramids and Stonehenge.(/a> [securityscale.com]
No, you are mistaken. I've always had this sig.
(Score: 2) by bob_super on Monday December 05 2016, @06:12AM
The heavier the trains, the more power you get. The more tracks you build, the more power you get.
This requires a massive amount of land and a lot of concrete, i.e. a massive amount of water, if only once.
Ant then you gotta maintain your oversized infrastructure, including you giant mobile engine/generators and their catenary/cables. And you get no savings as this is so site-sensitive (and automatically distant from the power users) that it won't scale to more than a few systems, ever.
It's not that it doesn't work, but I wouldn't put my money on it.