Base load refers to the minimum amount of electric power delivered or required over a given period at a steady rate. Base load power plants operate continuously because they are the most efficient and lowest-cost generators. Coal, nuclear, and large hydroelectric plants traditionally serve base load demand. As renewables grow, the concept of base load is evolving, solar and wind can now contribute to base load in some regions, supported by battery storage.
Base Load
The minimum level of electricity demand over a 24-hour period, typically supplied by always-on power plants.
Related Terms
Peak Demand
The maximum electricity consumption in a grid during a specific period, typically hot summer afternoons.
Capacity Factor
The ratio of actual electricity output to maximum possible output over a period, measuring plant efficiency.
Generation Mix
The combination of energy sources (coal, gas, nuclear, renewables) used to produce a state's electricity.
this entity is one of the U.S. state-level electricity rates and generation mix concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the the EIA Open Data API and State Electricity Profiles data behind every per-entity page on the site.
In the the EIA Open Data API and State Electricity Profiles data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.
Source: U.S. Energy Information Administration, 2026.