Customer choice programs are an important stimulus for growth in renewable energy supply. In 2006, total utility green power sales exceeded 3.5 billion kWh, about a 30 percent increase over 2005. More than 500,000 customers are participating in utility programs nationwide, up more than 10 percent from 2005.

Each year, the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) acknowledges the leading programs and the utilities that run them.

NREL develops Top 10 rankings of utility programs in the following categories. Here are the top-ranked utilities in each category:

Sales: Austin (Texas) Energy

Customer participation rates: City of Palo Alto (Calif.) Utilities

Number of participants: Xcel Energy

The category of lowest premium price charged is the most complicated. Customers in some programs are exempt or protected from changes in utility fuel charges. Thus the "premium" for renewable energy from Austin Energy was actually a credit of a fraction of a penny per kWh as of December 31, 2006, the data cutoff for the lists.

Utility green pricing programs are one segment of a 2,500 MW green power marketing industry. Companies served by multiple utilities, such as Starbucks and PepsiCo, often prefer to go through brokers to buy renewable energy in the form of RECs that cover all locations nationwide.

NREL analysts attribute the success of utility programs to persistence in marketing and creative marketing strategies. Utility partnerships with independent green power marketers also deserve credit.

Under these voluntary programs, consumers can choose to help support additional electricity production from renewable resources such as solar and wind. More than 600 utilities across the United States offer these programs.