While Congress and the EPA have struggled with a federal program to reduce greenhouse gas (GHG) emissions, a majority of the states have moved ahead with programs intended to cut GHGs by increasing the use of alternative energy sources, such as wind and solar.

So-called Renewable Portfolio Standards (RPS) or goals are in effect in 33 states plus Washington, D.C. The standards set a deadline by which electric utilities must generate a specified percentage of their power from renewable energy sources. The percentages and dates vary–for example, Michigan requires that utilities generate 10 percent of their power from renewable sources by 2015, while Connecticut requires 27 percent from renewables by 2020. The definition of what constitutes a renewable source also varies by state.