U.S. State Electricity Portfolio Standards

Thirty states and the District of Columbia require electric utilities to deliver a certain amount of electricity from renewable or other clean electricity sources. Most of these requirements take the form of either:

  • a renewable portfolio standard (RPS)—adopted by 20 states and the District of Columbia—requires a certain percentage of a utility’s electricity to come from renewable energy sources
  • a clean energy standard (CES)—adopted by nine states—requires a certain percentage of a utility’s electricity to come from low- or zero-carbon emitting energy sources

The standards range from modest to ambitious, and qualifying electricity sources vary. Some states also include “carve-outs” (requirements that a certain percentage of the portfolio be generated from a specific energy source, such as solar power) or other incentives to encourage the development or maintenance of particular resources (e.g., nuclear power) in their standards.

Eight states have voluntary electricity goals, which generally lack enforcement mechanisms, unlike states with legally binding standards. Some states have multiple, legally binding standards. For example, Massachusetts has an alternative portfolio standard (APS), RPS, and CES.

Although climate change may not be the primary motivation behind the implementation of these standards, the use of renewable or clean energy can deliver significant greenhouse gas reductions. Other benefits of increasing a state’s use of zero-emitting energy include job creation, energy security, and cleaner air. The majority of states passed or strengthened their standards after 2000; consequently, while many of these efforts have increased the penetration of renewables, others have not been in effect long enough to do so. Many states allow utilities to comply with the RPS, CES, or APS through tradeable credits.

While the success of state efforts to increase renewable or alternative energy production will depend in part on federal policies like production tax credits, states have been effective in encouraging the deployment of clean energy generation.

Last Updated February 2022