For years, District Energy St. Paul has been phasing out its use of coal to heat buildings downtown, in Energy Park and in Duluth. On Sunday, the nonprofit utility company burned its last load of coal.

The elimination of coal comes two years earlier than originally planned.

“It’s exciting,” said Ken Smith, District Energy president and CEO. “District Energy has been wanting to do this for a very long time.”

By cutting out coal, officials say they will reduce the heating system’s carbon-dioxide emissions by 16 percent. That equates to about 10,000 tons per year — as much as removing 2,100 cars from the road annually.

When District Energy began serving customers in 1983, it burned coal to heat the water that circulated into the heating systems of connected buildings. In 2003, District Energy installed a biomass-fired combined heat and power plant in its 100-year-old former coal burner along Kellogg Boulevard in downtown St. Paul. As a result of that, and improved energy efficiency, Smith said District Energy had reduced carbon emissions from its heating operations by 57 percent.

Instead of coal, the combined heat and power plant burns about 250,000 tons of waste wood chips annually. The wood waste comes from throughout the Twin Cities area, mainly trees that were damaged by storms, residential yard waste and, more recently, trees cut down as area cities deal with the infestation of the emerald ash borer.

District Energy St. Paul heats 197 buildings and 300 single-family homes and cools another 116 buildings in downtown St. Paul and surrounding areas.

Smith said District Energy is planning several additional steps over the next few months to further reduce the system’s carbon footprint. Company officials expect to announce those moves, and the utility’s greenhouse gas reduction goals, by July.

“We are in those discussions right now,” he said. “This [eliminating coal] has been a major item for us to check off the list. And to get this goal completed is excellent.”

In response to growing international interest in District Energy’s St. Paul operations, the utility created a subsidiary called Ever-Green Energy in 1998. Ever-Green Energy is working — either as a consultant or in management and operations — on energy projects throughout North America.