Twenty-five states and the District of Columbia require electric utilities to deliver a certain amount of electricity from renewable or other clean electricity sources. Eleven states have requirements or goals that have expired, have not been re-upped, or have been repealed. Most of these requirements take the form of either:

• a renewable portfolio standard (RPS) — adopted by 18 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 8 states — requires a certain percentage of a utility’s electricity to come from low- or zero-carbon emitting energy sources
• an alternative portfolio standard (APS) requires a certain percentage of a utility’s electricity to come from other energy sources that are not necessarily renewables (e.g., combined heat and power, storage, efficient steam technologies).
• electric sector zero-emission standards — adopted by Colorado, North Carolina, and Oregon – require utilities to achieve an emissions reduction of 100 percent or carbon neutrality relative to a baseline.

Qualifying electricity sources vary for these ambitious standards. 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.

Colorado, North Carolina, and Oregon’s electric sector emissions standards operate through utility plans for emissions reduction submitted to their state public utility commissions. In 2019, Colorado enacted legislation that requires utilities serving greater than 500,000 customers to supply 80 percent of retail sales with clean energy sources by 2030 and 100 percent of retail sales with clean energy sources by 2050. In 2021, North Carolina enacted legislation that requires the Utility Commission to reduce power sector carbon dioxide emissions 70 percent from 2005 levels by 2030 and achieve carbon neutrality by 2050. In 2021, Oregon enacted legislation that requires retail electricity providers to reduce greenhouse gas emissions associated with electricity to 80 percent below baseline emissions levels by 2030, 90 percent below baseline emissions levels by 2035 and 100 percent below baseline emissions levels by 2040.

Six 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. Twelve states have also passed technology-inclusive clean energy policies, which allow for the support of technologies such as nuclear or carbon capture and sequestration (CCS).

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 August 2024.