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Fw: Could A Donut-Shaped Island Create Permanent Renewable Energy?

From: user 6.
Sent on: Tuesday, April 2, 2013 12:42 PM
Here's another idea for expanding pumped hydro - except you're eliminating the "pumped" and the "hydro"
Instead, we should call it "gravity storage"

Jim Kelly thinks he has the energy storage solution. In his 38 years in various R&D and engineering executive positions at Southern California Edison, Kelly built several pumped-storage hydropower facilities. Next month, on a ranch in the Tehachapi Mountains owned by one of the founders of the wind energy industry, Kelly’s company, Advanced Rail Energy Storage, will begin testing a variation on pumped hydro. Except instead of dams, channels, and water, Kelly’s new system has rail yards, train tracks, and electric locomotives hauling boxcars full of gravel.

These heavy-haul trains, borrowed from mining applications, use the same software as computerized trains at many airports. A motor hooked up to an electric third rail draws electricity from the grid to push the trains up a 7 to 8 percent slope; at the top, the energy is stored as potential energy. When the grid needs the watts back, the software allows the trains to run downhill at about 35 miles per hour, "releasing energy all the way," Kelly explains. The locomotive’s motor becomes an electric generator, pushing the electricity back into the electrified rail and from there, to the grid. A large-scale storage facility that could handle 500 megawatts or more would take about 8 miles of track. The heavy boxcars are connected and disconnected according to how much power is being stored or sent back. The trains can store the power for an hour, a week, or a month with no loss over time—gravity doesn’t decay. And Kelly says they can achieve up to 90 percent efficiency. DWP’s Howard said that Kelly’s idea sounds "intriguing" and thinks it could work.

(from article "Boxcar Energy" By Paul Tullis, March 28, 2013. The rest of the article summarizes other existing storage solutions, including pumped hydro, batteries, etc.)

Sent: Sunday, March 24,[masked]:01 PM
Subject: Could A Donut-Shaped Island Create Permanent Renewable Energy?

Probably the biggest problem with wind and solar is they are intermittent - they don't generate power all the time. 
The solution is energy storage, but that's expensive.  Many institutions are searching for ways to make it cheaper.
The cheapest solution right now is pumped hydro:  use excess wind and solar energy to pump water up a hill to a storage lake, then when energy is needed let the water run back down through turbines and generators.  The problem is you need a hill (preferably a big one) next to a water source (preferably a big one).  That severely limits where you can use pumped hydro.
Here's an idea which can expand the number of places where pumped hydro can be used:
Steve Barbie

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