More than 600 utilities in 37 states offer green energy, but unless you read the fine print on your bill, you may not know if your power company is one of them. (To find out, visit eere.energy.gov/greenpower.) If you don't live in a green power zone, you can support the industry by buying renewable energy certificates, which allow you to purchase green energy in another part of the country. The extra dollars will dispense green power to the national power grid.