Gravity storage has been on the minds of green energy enthusiasts for years, as the dominant method so far of helping renewable energy become reliable energy.
Jim Kelly, CEO of Advanced Rail Energy Services in California, is looking forward to testing out a means of storing electricity that is efficient, innovative and unexpected –– by moving trains.
An engineer with Southern California Edison for 38 years, Kelly and his team at ARES want to store the excess energy created by photovoltaic solar panels and wind turbines, and use it to move trains, weighed down with cars filled with gravel, up an incline, where they would wait and hold onto the energy used to get them there.
When that energy is needed again, the trains would be allowed to roll back down the hill at up to 35 mph, and the electric motor that used electricity from the power grid to push the train uphill would become a dynamo, pumping electricity back into the same grid.
The idea operates on the same principle as pumped-storage hydropower, where energy is used to push large quantities of water uphill, or into a tower or behind a dam. Then, when the energy is needed, the water is released through a turbine, which releases the energy back.
The water systems work, which is why the method currently “accounts for 93 percent of energy storage worldwide,” according to Slate, but it takes a lot of water, which is usually hard to find in the kinds of places that have the bright sun and high winds that are generating the power in the first place.
Kelly’s train project has its challenges as well, requiring eight miles of track to store 500 megawatts of electricity. But it can also hold the energy forever, or as long as the train doesn’t move and the law of gravity doesn’t change.
Though it's just a first step, the city of Los Angeles is considering Kelly’s proposal as one of a series to help wean the city of fossil fuels forever.
But first, energy storage needs to make some serious progress.
“It’s going to take a rotary phone-to-iPhone type of leap,” Panama Batholomy, an adviser to the California Energy Commission, said to Slate.