The Center for Climate and Energy Solutions released a study November 17 that found that a federal clean energy standard offers a flexible way to meet clean energy goals. The report, Clean Energy Standards: State and Federal Policy Options and Implications, also said that without new policies to promote clean energy, the nation’s renewable power capacity will remain largely the same for at least the next 25 years. Currently 31 states and the District of Columbia have renewable or alternative energy portfolio standards, and another eight have voluntary clean energy goals.