Storing energy in gravity is a possibility
Currently, the U.S relies upon fossil fuels such as coal and natural gas to generate two thirds of its power. While alternative energy such as solar and wind are picking up momentum, their unpredictable nature make them unreliable.
Advanced Rail Energy Storage, a California based company is working on an interesting solution using gravity to store the energy instead of an battery.
The power generation system is comprised of a small electric railroad that takes the power from the wind or solar farm when there is a surplus of energy. Advanced Rail Energy Storage drives train cars loaded with heavy rocks/weights up a slope.
The operator would let the train car roll down the slope when there is a shortage. The system collects the energy generated from the brake, similar to the technology used in a Formula 1 race car, to feed into the power grid.
This company recently received approval to build a commercial 50-megawatt storage and production facility in southern Nevada. This facility will include a 5.5 mile railway with a 2,000 foot grade.
The facility, which will be completed in early 2019 will use train cars that are loaded with precisely 9,600 tons of weight at full scale.
It would have a power capacity of 50 megawatts and can produce 12.5 megawatt-hours of energy.