You can take advantage of alternative energy – and brand yourself environmentally friendly – by signing up with your local utility if you live in Iowa, Minnesota, Montana, New Mexico and Washington.There, alternative energy mandates allow utility customers to sign up to buy “green” energy from wind, solar, geothermal and even hydropower installations.For a few cents more than the cost of conventional energy sources like coal, natural gas and oil, customers can purchase alternative energy. Of course, there is no way of knowing for certain that you’re actually buying kilowatt hours from solar, for example, but you have the comfort of knowing that your few extra pennies will help maintain and expand green power options.Elsewhere in the country, even though green power isn’t a mandate, utilities do sponsor green energy programs, and you can participate in these by simply calling, or e-mailing, your provider.The National Renewable Energy Laboratory, or NREL, has ranked nationwide utilities in two categories, sales and customer participation. In the first category, the top utilities offering green power programs are: Austin Energy (Texas), Portland General Electric (Oregon), PacifiCorp (California) and Xcel Energy (Colorado, Minn.). In the second category, the top-ranked utilities are: City of Palo Alto (Calif.) Utilities, Lenox (Iowa) Municipal Utilities, Montezuma (Iowa) Municipal Light & Power, Portland General Electric, and Sacramento (Calif.) Municipal Utility District.Of course, if your area utility doesn’t offer green power, and state and federal tax incentives (like the Clean Energy Tax Stimulus Act of 2008) aren’t enough to make a your own personal rooftop solar program affordable, you can sign up with One Block Off the Grid, or 1BOG, whose volume pricing can reduce upfront solar installation costs by up to half.You can participate if you own your own home and are the client-of-record on the utility bill. You will have to commit to certain energy-saving measures, such as using compact fluorescent bulbs and using the dishwasher at night, but the solar bargaining collective, which started in San Francisco and now networks 20 cities, assures customers it can deliver a solar system for about $6,000 for a two-kilowatt array.1BOG now operates in the following cities: Aspen, CO; Austin, TX; Bergen County, NJ; Berkeley, CA; Boston, MA; Brooklyn, NY; Chicago, IL; Denver, CO; Las Vegas, NV; Los Angeles, CA; New Orleans, LA; Miami, FL; Oakland, CA; Portland, OR; Sacramento, CA; San Diego, CA; San Francisco, CA; San Jose, CA; Seattle, WA; Washington, DC.With the number of utilities and solar power companies participating in green energy programs, many of them incorporating solar or using solar as an exclusive platform, there is no longer any excuse for not going green. It’s a shame to waste a perfectly good sun.