Renewable portfolio standard
Many countries (and states in the USA) require utilities to buy a specified amount of their electricity from designated “renewable” sources, such as wind and solar but usually excluding existing hydro. This is called a “renewable portfolio standard” (RPS), “renewable electricity standard”, or “renewables obligation”.
Such a directive has little regard for cost, practicality, or science but is instead primarily an act of political virtue signalling.
Or it is a cynical act of crony capitalism: Besides placing burdens on utilities and ratepayers, an RPS serves to create a obligatory market for energy sources that would otherwise find it difficult to compete with more reliable and cheaper sources. Combined with subsidies, e.g., PTC, Feed-in tariff and the extra market for “green tags”, an RPS helps to guarantee attractive returns and tax avoidance for the investors in these “preferred” technologies.