Grid balancing

[2] In a deregulated grid, a transmission system operator is responsible for the balancing (in the US electric system smaller entities, so called balancing authorities, are in charge, overseen by reliability coordinators[3]).

[5] As of the beginning of 2020s, the actual balancing service was provided primarily by the conventional power stations: [1] frequently, the only quick-response safety margin is the inertial response provided by the kinetic energy of the physically rotating machinery (synchronous generators and turbines).

If there is a mismatch between supply and demand the generators absorb extra energy by speeding up or produce more power by slowing down causing the utility frequency (either 50 or 60 hertz) to increase or decrease.

In Scotland this has resulted in payouts,[6] most recently over £6m in 33 days has been paid by the grid to wind farms to not generate electricity.

In areas with little hydroelectricity, pumped storage systems such as the Dinorwig Power Station can allow the energy to be used for operational reserve or at times of peak demand rather than run a natural gas peaking power plant.

Energy from wind, sunlight or other renewable energy is converted to potential energy for storage in devices such as electric batteries or higher-elevation water reservoirs. The stored potential energy is later converted to electricity that is added to the power grid, even when the original energy source is not available.