Carbon taxes have been a subject of debate in the United States, the world's leading consumer of fossil fuels, as some communities try to reduce the output of gases scientists link to global warming.

Syndicated New York Times columnist Thomas Friedman and others have argued for a gradual increase in US gasoline taxes. That would bring motor fuel prices up closer to prices paid in Europe and fund projects to develop alternative energy and make cars more efficient. So far, that idea has found scant support.

The Boulder tax will raise average home bills US$1.33 per month and businesses will pay an extra US$3.80 per month, according to the town. The tax will generate about US$1 million for the city annually. Utility Xcel Energy will collect the tax.

The money will fund energy audits for homes and businesses and visits by energy experts to advise homeowners how to save energy through means such as energy efficient lighting and insulation.

Residents that choose to purchase wind power will not be assessed the tax.

The measure introduced in August by the City Council won with about 58 percent of Tuesday's vote, said Sarah Van Pelt, Boulder's environmental sustainability coordinator. A business group, Boulder Tomorrow, opposed the tax.