Curtailment (electricity)

In the electric power industry, curtailment is an involuntary reduction of the electric generator output ("dispatch down") made to maintain grid stability (for example, in grid balancing). While curtailment is a standard technique that has been applied throughout the history of electric power production, in the 21st century it has become an economic issue for the owners of wind and solar generation plants. These variable renewable energy plants, due to the absence of an expendable resource (like fuel), have quite low marginal electricity production costs, so curtailment affects the economics of projects in a much more significant way than with conventional units.

Curtailment is a loss of potentially useful energy and may impact power purchase agreements. However, using all available energy may require costly methods such as building new power lines or storage, becoming more expensive than letting surplus power go unused.