Thermal Energy Storage: A Low-Cost Option for Electricity Storage
The integration of increasing amounts of intermittent renewable energy sources into the grid has some utilities concerned about the duck-shaped load curve, which creates ramping challenges in the late afternoon as electricity usage rises and wind and solar generation diminishes. Existing technologies offer some simple solutions. At the Winter Meetings of the National Association of Regulatory Utility Commissioners (NARUC), Jim Lazar highlighted two of ten low-cost strategies for aligning resources and load to make the load curve easier to serve.
Electric water heat accounts for 4 percent of electricity consumption in the United States. If system operators could harness water heaters to provide ancillary services to the grid, either decreasing or increasing load as needed to keep the grid balanced when wind or solar production may vary, the amount of renewable resources on the U.S. electric grid could be doubled without disrupting customers’ hot water usage. Along the same lines, ice or chilled water storage can be implemented to shift the majority of the system load for air conditioning off peak, while still providing cooling when needed. Mr. Lazar encourages regulators and utilities to consider these forms of thermal storage, which are much cheaper than batteries, pumped storage, compressed air energy storage, or other methods to store electricity.