Renewable portfolio standard

A renewable portfolio standard (RPS) is a regulation that requires the increased production of energy from renewable energy sources, such as wind, solar, biomass, and geothermal. Other common names for the same concept include Renewable Electricity Standard (RES) at the United States federal level and Renewables Obligation in the UK. The RPS mechanism places an obligation on electricity supply companies to produce a specified fraction of their electricity from renewable energy sources.

Source: Wikipedia — Renewable portfolio standard (CC BY-SA 4.0)