Baseload

Baseload is the floor of the demand curve: the level below which system load never falls in a given period. In most European grids the overnight minimum sits at roughly 40 to 60% of the annual peak load; in Germany, for example, load rarely drops below about 35 to 40 GW against a winter peak near 80 GW (ENTSO-E data).

The term also describes a class of generators, typically coal, lignite and nuclear plants, whose high CAPEX, low fuel cost and slow ramping made it economic to run them at capacity factors of 80 to 93%. US nuclear has averaged above 90% since the early 2000s (EIA).

With rising shares of variable renewable energy, the concept is shifting. What remains after subtracting wind and solar output, the residual load, can fall close to zero or turn negative on sunny, windy days, which removes the steady market niche that inflexible baseload plants relied on. Planners now speak less of baseload and more of firm, flexible capacity: resources that can be dispatched or ramped on demand, including storage, hydro, gas and demand response.

Baseload plants can still be valuable for energy volume and low marginal cost, but their revenue increasingly depends on flexibility, not just availability.