Consumers are playing a small but increasing role in driving the US wind power market through voluntary purchases of green electricity. "Utility green power sales continue to show strong growth across the country," says Lori Bird at the National Renewable Energy Laboratory (NREL) on the release of its annual ranking of the leading green power purchase programs in the country. In 2006, total utility green power sales exceeded 3.5 billion kWh, about a 30% increase over 2005. More than 500,000 customers are participating in utility programs nationwide, up more than 10% from 2005. Ranked by renewable energy sales, the green power program of Austin Energy (Texas) is first in the nation, followed by Portland General Electric, Florida Power & Light, PacifiCorp and Xcel Energy. Since many of the more than 600 utility green power programs across the country include kilowatt hours from a mix of renewables, assessing wind power's contribution is less precise. Wind power, however, rarely provides less than 90% of the green power in these programs and often comes close to 100%. Three overall top green pricing programs for 2006 are solely wind-sourced. Among these, Xcel Energy sold an average continuous capacity of 27 MW, up from 16.9 MW in 2005; Basin Electric Power Cooperative sold 24.8 MW, up from 13 MW the previous year: and OG&E Electric Services sold 15.4 MW, up from 7.3 MW. NREL researcher Blair Swezey attributes the rise partly to improved marketing of green power packages, but also to a drop in the rate-premium associated with buying electricity from renewable energy technologies.