Water Energy Bank, Shifting California State Water Project Pumping Using Aquifer Storage

The growth of renewable energy generation, as a result of California energy and environmental policies, has caused a surplus of power during the spring months when there is ample solar and wind generation but relatively low electricity demand, resulting in relatively low energy costs. This imbalance between springtime renewable power supply and demand is projected to increase as more renewable energy is brought on-line. In contrast, during the summer months, there is insufficient renewable energy supply to meet all demands; this requires bringing temporary power on-line to meet demand, which then results in relatively high energy costs.

One of the largest uses of electricity in California (up to 3 to 4 percent of the total) is the California State Water Project, which pumps water over the Tejon Pass from Northern to Southern California. This report includes an analysis that determines the benefits of shifting water pumping from high to low energy demand periods by using aquifer storage at the Willow Springs Water Bank. This analysis indicates that shifting California State Water Project pumping can reduce both energy-related operating costs and greenhouse gas emissions, help California integrate renewable energy sources, and operate the power grid at a lower cost. The Willow Springs Water Bank aquifer storage facility can be used as a “water-energy bank” to create a seasonal shift in California State Water Project pumping while entirely preserving all aspects of the project’s water supply deliveries, reliability, and timing to Southern California. This study characterizes both the potential amount of seasonal water shift and the potential cost and savings benefits of a water-energy bank under an avoided cost analysis and total resources cost savings framework.