|Sent on:||Tuesday, April 2, 2013 12:42 PM|
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, Kellys company, Advanced Rail Energy Storage, will begin testing a variation on pumped hydro. Except instead of dams, channels, and water, Kellys 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 locomotives 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 timegravity doesnt decay. And Kelly says they can achieve up to 90 percent efficiency. DWPs Howard said that Kellys 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.)