One of the oft-cited disadvantages of wind power is the lack of constancy of the energy source: power is available only when there is wind. Supply rarely matches demand.
This disadvantage would not exist if there were a “perfect battery”, i.e., a method for the energy to be stored so it can be made available to meet demand, and not just when the wind is blowing.
Such a battery exists for hydro-electric power: the dam. Since wind power does not have a counterpart, current wind farms are really no more sophisticated than placing small water turbines along a flowing river. If that approach doesn’t seem efficient, it’s because it isn’t, even if the flow of water is reliably constant.
One way to save up the energy of a wind turbine would be to use its energy (either mechanically or electrically) to raise a heavy load from one elevation to a higher one. I call this the grandfather clock approach. Like lifting the weight on a grandfather clock, a wind turbine can convert its kinetic energy to stored potential energy in a similar fashion. When the supply of wind exceeds energy demand, the weight is lifted; when it falls below demand, the weight descends. A reduction gear assembly regulates.
We have solved the constancy problem, but added to the complexity. We need a system of weights and regulators. In a large wind farm, it wouldn’t be practical for every wind turbine to have its own weight battery. Why not have the turbine array power a single, large battery?
One such battery could be a large water reservoir at a high elevation. The array of wind turbines could provide the pumping power to pump water from a low source (or sources) to the higher reservoir. The potential energy of the water stored in the reservoir could then be used to provide hydroelectric power as it flows back down to replenish its original sources.
Such a system solves 90% of the perfect battery problem. We now have delinked the unreliable wind supply from the potential energy demand. But we have introduced another potential inconstancy: a reliable source of water. During long droughts with little wind, the reservoir supply could fall below an exploitable threshold.
But there is a simple solution to the water supply challenge: wastewater, which is always in ample supply. Rather than dumping directly into a river after treatment, the water could be used to supply the reservoir.
But how many reservoirs exist at altitude? And how many could be constructed without significant environmental impact? These are engineering questions left to the engineers and environmental experts. Obviously, mountainous areas would have geographic and physical advantages over the prairie for this type of system. Our most populous state is blessed with the Sierra Nevada, ideal for many perfect batteries.
The Sierra Nevada is not only located adjacent to huge wind farms, it’s a short pipeline distance from the largest body of water on Earth: the Pacific Ocean.
However, seawater is salt water, and we don’t want to create a salt water reservoir high in the Sierra Nevada. But we won’t have to: we already have Mono Lake, a saline lake which needs salt water because of diversions from its watershed.
Mono Lake is our perfect battery. The energy from the wind farms supplies sea water to Mono Lake when the wind is blowing, and hydroelectric turbines meets electric demand as the water flows out of the lake back to the sea — in pipelines.
But do we really want to pipe the salt water all the way back to the sea? Why not use a fraction of the hydroelectric power generated to desalinate the water? This desalination plant would provide a bonus supply of fresh water to a water-starved state.