Politically "red" and "blue" US states are increasingly turning green as they push energy efficiency and renewable power to save money and protect the planet, says a report today with prominent bi-partisan support.

In the last two years alone, GOP-dominant red states have adopted policies that could serve as models for others seeking to meet proposed federal targets for reducing heat-trapping carbon dioxide emissions, according to the "State Clean Energy Cookbook" by Stanford University and the Hoover Institution.

Californian wind farms: support from both sides of US politics for renewables.

"There's no blue or red tinge to it. It's across the board," says George P. Shultz, co-chair of Hoover's Shultz-Stephenson Task Force on Energy Policy and U.S. secretary of State, Treasury and Labor under two GOP presidents. He says the new report shows "what works and what doesn't."

--Mississippi updated its commercial building code last year to a strict international standard that limits energy use, becoming the first Southern state to do so. Prior to the update, in 2012, the American Council for an Energy-Efficient Economy ranked it lowest among states for energy efficiency.