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 generally places an obligation on electricity supply companies to produce a specified fraction of their electricity from renewable energy sources. Certified renewable energy generators earn certificates for every unit of electricity they produce and can sell these along with their electricity to supply companies. Supply companies then pass the certificates to some form of regulatory body to demonstrate their compliance with their regulatory obligations. Because it is a market mandate, the RPS relies almost entirely on the private market for its implementation. Unlike feed-in tariffs which guarantee purchase of all renewable energy regardless of cost, RPS programs tend to allow more price competition between different types of renewable energy, but can be limited in competition through eligibility and multipliers for RPS programs. Those supporting the adoption of RPS mechanisms claim that market implementation will result in competition, efficiency and innovation that will deliver renewable energy at the lowest possible cost, allowing renewable energy to compete with cheaper fossil fuel energy sources.

RPS-type mechanisms have been adopted in several countries, including Britain, Italy, Poland, Sweden, Belgium, and Chile, as well as in 30 of 50 U.S. states, including the District of Columbia. Regulations vary from state to state, and there is no federal policy. Together these thirty states account for more than 42 percent of the electricity sales in the United States.

RPS mechanisms have tended to be most successful in stimulating new renewable energy capacity in the United States where they have been used in combination with federal Production Tax Credits (PTC). In periods, where PTC have been withdrawn the RPS alone has often proven to be insufficient stimulus to incentivise large volumes of capacity.

In 2007, the Edison Electric Institute, a trade association for America’s investor-owned utilities, reiterated their continuing opposition to a nationwide RPS; among the reasons included were that it conflicts with and preempts existing RES programs passed in many states, it does not adequately consider the uneven distribution of renewable resources across the country, and it creates inequities among utility customers, by specifically exempting all rural electric cooperatives, and government-owed utilities from the RES mandate.

In 2009, the US Congress has been considering Federal level RPS requirements. The "American Clean Energy Leadership Act" reported out of committee in July by the Senate Committee on Energy & Natural Resources includes a Renewable Electricity Standard that calls for 3% of U.S. electrical generation to come from non-hydro renewables by 2011–2013.