A renewable portfolio standard (RPS) aims to ensure a market for the power produced by renewable energy providers, mandating a target and letting the market decide what technologies are deployed. As of September 2009, 29 states and the District of Columbia have implemented RPS policies, and five additional states have set non-binding renewable energy goals.

Twenty-three U.S. states and four Canadian provinces are actively participating in the design and implementation of three regional cap-and-trade programs to reduce greenhouse gas emissions (the Regional Greenhouse Gas Initiative - RGGI; the Midwestern Greenhouse Gas Accord; and the Western Climate Initiative - WCI). Participating U.S. states account for one-half of the U.S. population and Gross Domestic Product (GDP), and one-third of all U.S. greenhouse gas emissions.

Regional Cap-and-Trade Agreements: Three mandatory regional carbon trading markets, the Northeast and Mid-Atlantic Regional Greenhouse Gas Initiative (RGGI), the Midwestern Greenhouse Gas Reduction Accord (MGGRA) and the Western Climate Initiative (WCI) are being established by state governors to limit emissions and spur energy innovation.

Energy Efficiency Resource Standards: Nineteen states have minimum energy efficiency resource standards which encourage more efficient generation, transmission and use of electricity and natural gas.

With action to capture feasible mid-term resources (particularly solar PV), the author's assessment suggests each state can generate renewable electricity equal to at least 20 percent of its current electric power sales.