Currently, 32 states and the District of Columbia (DC) have renewable portfolio standards (RPS), standards that require a specific percentage of renewable energy in an electricity sale. Twenty-six states and DC have emission reduction targets , 18 states and DC have clean energy targets, and 21 states and DC aim to achieve either a 100 percent emission reduction or a 100 percent clean energy goal.
In response to climate change, emission reduction and clean energy goals have become increasingly common, and many states that have adopted RPS do not yet have either an emission reduction or a clean energy goal. The first RPS policy can be dated back to 1983 when Iowa passed the Alternative Energy Production Law, which required the state’s investor-owned utilities to purchase an average of 105 megawatts of electricity from renewable energy sources. It was not until twenty years later that Maine enacted the nation’s first greenhouse gas emission reduction legislation in 2003. According to an article in The Energy Journal, states that have adopted RPS policies were likely driven by factors like “strong renewable potential, a restructured electricity market, a small share of natural gas in the electricity fuel mix, strong Democratic presence in the state legislature, and organized renewable energy interests.” This may explain why some states have adopted RPS policies but not yet emission reduction or clean energy targets: RPS legislation can be driven by politics, private interests, or renewable energy potential.