Grid-Scale Electricity Storage

Grid-scale electricity storage policies require minimum levels of energy storage such as batteries, pumped hydro, or compressed air, to store electrical energy. Typically, storage policies set a minimum level of storage capacity that must be achieved in a target year with clear, annual targets ramping up to the final year value. This additional storage increases the flexibility of the electric grid, enabling a more dynamic balance between variable generation and variable demand.

In the EPS, a storage mandate can be represented with the mandated grid battery construction lever (Boolean Use Non BAU Mandated Grid Battery Capacity Construction Schedule). In the BAU case, the model builds a scheduled quantity of grid battery capacity each year from input data (BPMGBSA BAU Policy Mandated Grid Battery Storage Additions), representing batteries that are planned or required regardless of their economics. When the lever is enabled, the model replaces that BAU schedule with a user-specified schedule of annual additions (PMGBSA Policy Mandated Grid Battery Storage Additions). Mandated batteries are added on top of any batteries the model builds for economic reasons, add to grid battery spending, and are available to the grid for storage dispatch. This lever is independent of the mandated construction lever for generating capacity (see Policy Mandated Capacity Additions and Retrofits).

Because energy storage represents a rapidly developing set of technologies, policies should be technology neutral and focus on acquiring storage capacity at least-cost. Reverse auctions, in which developers submit bids to the body choosing projects, are an effective mechanism for minimizing costs and remaining technology neutral.