Dominick's grocery stores announced a conversion of its truck fleet to biodiesel Thursday, a move it estimates will eliminate more than a million pounds of carbon emissions annually.

President Don Keprta said Dominick's is the first retailer in Illinois to convert its entire fleet -- including 78 tractors and 350 refrigerated trailers -- to biodiesel. “This is a huge step in lessening our impact on the environment,” Keprta said at a news conference Thursday.

Dominick's, which operates 99 stores in the Midwest, is owned by retail food and drug giant Safeway Inc., which said it will convert its entire national fleet to a biodiesel blend.

Mayor Daley attended the announcement at a Dominick's store in the city's Ukrainian Village neighborhood, using the occasion to promote his goal of making Chicago the nation's greenest city.

 “We are able to carry out the message to the business community that as the city moves forward it must do so in a way that saves energy, saves money for businesses and its individuals, and creates economic opportunity for its residents,” Daley said.

The grocery store chain also became the first retailer to join the Chicago Climate Exchange, a trading system to reduce greenhouse gas emissions. Joining the exchange is voluntary, but members are legally obligated to meet yearly emissions reductions.

Richard Sandor, chairman and CEO of the Chicago Climate Exchange, lauded the "creativity" the grocery chain showed in converting its vehicles to B20, a mixture of biodiesel and regular petroleum diesel. He said switching to biodiesel reduces greenhouse gas emissions by 78 percent.

“We think that Chicago is the natural home for environmentalism, and it’s the natural home for exchanges and trading,” Sandor said. “The marriage of those two will show that financial incentives can lead to great social objectives.”