It is only the 10th municipality in the nation and the third in Utah - with Park City and Moab - to earn the distinction.

To qualify, Alta's government, businesses and residents collectively had to buy at least 3 percent of their power from a renewable-energy source.

In Alta (population 365), 9 percent of all electricity consumed is bought as wind power through Rocky Mountain Power's Blue Sky program, which adds renewable energy to the grid instead of conventional coal-fired power if customers volunteer to cover the additional cost.

"We survive by having a good snowpack" for skiing and for the Salt Lake Valley's water supply, said Alta's assistant town administrator, Laura McIndoe. "We'd like to limit our use of fossil fuels and other types of energy that not only pollute the air but also contribute to global climate change."

Alta's green-power purchases prevent 1,045 tons of carbon dioxide from being released into the atmosphere each year. That's the equivalent of keeping 179 cars off the road.

Only 14 of Rocky Mountain Power's 226 residential customers in Alta participate in Blue Sky. The bulk of the community's green power is bought by Alta Ski Area, which purchases 75,000 kilowatt hours per month - or 23 percent of its electricity usage.

The town of Alta buys 5,700 kilowatt hours of Blue Sky energy per month, representing 30 percent of the government's needs.

rwinters@sltrib.com