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Unconventional “Hydraulic Hydro Storage” System Offers Energy Storage for the Grid on a Grand Scale
Author: Will Bierbower
One of the main barriers to the diffusion of renewable energy sources such as wind and solar power is their inherent variability. If excess energy produced could be stored cheaply and used during times of lower production, this issue could be largely mitigated. Several technologies are under development as possible options for storing energy from the grid, including batteries that store energy in chemicals, mechanical flywheels that store energy as rotational energy, and hydroelectric dams that convert mechanical energy into electrical energy by retaining and channeling rivers.
And, on the bizarre end of the spectrum, we can find a hydraulic water storage system proposed by physicist Dr. Eduard Heindl, a professor at Furtwangen University in Germany.
Heindl’s idea is to store potential energy by using water as a hydraulic fluid to transfer power underground. A project would involve carving out a gigantic cylinder of dense rock, such as granite, by drilling two underground circular tunnels with 500-meter radiuses, one tunnel several hundred meters deep and another at a 1-kilometer depth directly underneath the first. A saw mill would be lowered into the tunnels connected to a saw mill at the surface via a wire saw. The saw mills would work away at the rock to separate the cylinder from the deposit. A seal would then be placed within the first tunnel to close off the system to prevent the loss of potential energy.
Water would be pumped down an adjacent mine shaft to the base of the cylinder. Under enough pressure, the rock cylinder (representing a “piston” in hydraulic engineering terms) would then lift, storing potential energy in the system as pressurized water. Extra electricity produced on the grid could be stored within the system by converting electric energy to mechanical energy using a generator to power the pump. When the grid required energy, the process could be reversed to generate electricity for the grid.
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