Most practitioners are familiar with the curtailment of variable renewable energy (VRE) resources like wind and solar photovoltaics as a reduced production of power relative to what would be available from the wind and solar resource. This curtailed energy is the difference between the total available energy and actual production. More generally, curtailment is the intentional reduction of instantaneous power from supply or demand resources to aid balancing of the electricity grid. It is more often applied to supply-side resources whose output is reduced relative to what would be available from the primary resource, regardless of technology type. This general definition is like the well-known “dispatch down” instruction a system operator would use for any resource to reduce their generation.
When the supply of wind and solar photovoltaics exceeds the demand for electricity, considering the operational constraints of remaining generators, operators cannot further integrate the available wind and solar energy and instead curtail (in the absence of demand-side participation, expanded networks, storage technologies or exports to neighboring systems). While curtailment can be a cost-effective alternative to network expansions when installing VRE, too much curtailment reduces the economic benefits of potential new wind and solar, considering their low marginal costs. Curtailment also limits the extent to which electric grids can decarbonize using VRE alone by limiting the contributions of VRE capacity. Building storage, implementing demand-side management, and/or expanding the network can help reduce curtailment and increase the use of available energy from VRE generators.
Learn more about these trends and their impact on the future of renewable energy integration by reading the full fact sheet.