At first it seems a bit counter-intuitive, you buy something and then sell back 85 percent of what you bought.
But it begins to make sense when you apply supply-and-demand pricing.
A company called Advanced Rail Energy Storage Nevada, or ARES, has been approved by the Bureau of Land Management to build a 50-megawatt electricity storage facility east of Pahrump that will use gravity-based railroad cars full of rocks. It has applied for approval of permits from the Nevada Public Utilities Commission.
The concept is to obtain electricity when it is plentiful and cheap, such as when windmills and solar power plants are producing at their peak, and use it to drive railroad cars six miles and up 3,000 feet on a hill in Carpenter Canyon east of Highway 160. When the wind dies down and the sun isn’t shining, there is still a high demand for power so the price goes up. When this happens the rail cars will be released so that gravity will propel them downhill at 18 miles per hour and the electric motors that drove them up the hill become generators producing electricity to upload to the grid.
Valley Electric Association, which serves the Pahrump area, plans to build power lines to connect to the project.
The cost of the project is $55 million and the company still needs to come up with the financing, according to Green Tech Media.
The company has built a pilot project in Tehachapi, Calif., near a massive wind farm.
ARES CEO Jim Kelly has been quoted as saying the system can “be deployed at around half the cost of other available storage technologies. Just as important, ARES produces no emissions, burns no fuel, requires no water, does not use environmentally troublesome materials and sits very lightly on the land.”
Francesca Cava, vice president of operations for ARES, writes, “It’s a wonderfully simple idea, a 19th century solution for a 21st century problem, with some help from the abundant natural resource that is gravity. When the local utility’s got surplus electricity, it powers up the electric motors that drag 9,600 tons of rock- and concrete-filled railcars up a 2,000-foot hill. When it’s got a deficit, 9,600 tons of railcar rumble down, and those motors generate electricity via regenerative braking — the same way your Prius does. Effectively, all the energy used to move the train up the hill is stored, and recouped when it comes back down.” Or at least 85 percent of it.
Kelly also said, “Fifty megawatts doesn’t get us to economies of scale. We are more efficient as we get larger.”
Similar concepts, but using closed loop water pumping, have been proposed by Eldorado Valley and Blue Diamond, but nothing has developed.