As more intermittent renewable energy sources, such as wind and solar, are added to the electric grid, pumped storage facilities are vital to stabilization of the electric grid. Traditionally, pumped storage facilities have been used to take advantage of the varying cost of electricity. During periods when the cost of power was low, such as nighttime hours, pumped storage facilities would draw water from a lower elevation reservoir and pump it to a higher elevation reservoir with that low cost electricity. As the price of electricity increased during the day, the pumped storage facilities would drain that water stored in the upper reservoir to the lower reservoir, through a hydraulic turbine generator, selling the generated power at a higher price point. However, with the heavy addition of intermittent renewable energy sources to the grid, the function and purpose of existing pumped storage facilities must change to help add stability to the grid. This will also enhance the potential of additional renewable energies.
Instead of pumping water to the upper reservoir during nighttime hours when the price point of power is low, pumped storage facilities should be operating when wind and solar facilities are at their peak loads. During these times, solar power plants and wind farms are generating excess power that must be stored. Storing this excess energy at pumped storage facilities provides a clean and environmentally-friendly way to keep the lights on when the wind and solar energy sources are unavailable. A fear that many consumers have with intermittent renewables is that power will not be available to them when it is needed. Utilizing pumped storage facilities to provide power to consumers when solar and wind is unavailable can help to alleviate this concern.
An informative article by the Los Angeles Times describes how California is producing a lot of excess energy during periods of high solar irradiance (intensity) and high wind speed because of its investment in renewable energy sources. Back in March, California was producing so much energy through renewable sources that they needed to give the excess power away. In some cases, they actually had to pay other states to take it. This has raised the cost of renewable energy and has forced it to become underutilized. Furthermore, this same excess energy was not available for use at night, raising the price point of power during nighttime hours in California. California should invest in additional pumped storage facilities to store this excess energy produced during daylight hours for use at night. Giving it away for free or paying other states to take it is not a sound economic model. As other states in the US begin investing in installation of intermittent renewables, they should consider repurposing existing pumped storage facilities to support nighttime operations for electric grid stability. The addition of more pumped stored facilities will be necessary as more energy is generated through renewable energy sources.