In electric grid power generators, curtailment is the deliberate reduction in output below what could have been produced in order to balance energy supply and demand or due to transmission constraints.
[5] Curtailment is a loss of potentially useful energy, and may impact power purchase agreements.
[8][9][10][11] After ERCOT built a new transmission line from the Competitive Renewable Energy Zone in West Texas to the central cities in the Texas Interconnection in 2013, curtailment was reduced from 8-16% to near zero.
[14] Curtailment has since increased[8][15] to 150-300 GWh/month in spring of 2020 and 2021,[16][17] mainly solar power at noon as part of the duck curve.
[20] In United Kingdom, 1.35 TWh of wind power was curtailed in early 2023.