The 538-megawatt plant, which produces enough electricity to supply 400,000 households, has been shut down while the cause of the explosion is under investigation by the Burnsville Fire Department and Xcel Energy, utility spokeswoman Patti Nystuen said.
The utility, which is based in Minneapolis, will buy additional power and does not supply anticipate problems, Nystuen said.
Burnsville firefighters were called to the plant, located on the Minnesota River at 1410 Black Dog Road E., at 7:25 a.m. after Xcel workers noticed smoldering in a coal bin, Nystuen said.
While firefighters were on the site, there was a "small explosion" in the sheet metal shed, Nystuen said.
As a precaution, Xcel workers shut down the plant's Unit 3 coal-fired boiler, which was closest to the explosion, and also the plant's Unit 4 coal boiler.
The plant's remaining boiler, called 5-2 because it replaced the old Unit 1 and 2 boilers with a modern natural gas unit, was already offline for maintenance, Nystuen said. It remained shut
At the time of the explosion, the plant had 44 Xcel workers, 24 contractors and 17 construction workers on site, Xcel spokesman Tom Hoen said.
The Black Dog plant, originally built in the 1950s, has not had an explosion or similar incident in the past 20 years, Hoen said.
However, in March 1989, the plant had to shut down after a line carrying lubricating oil for one of the plant's turbines ruptured, spilling oil that ignited and caused a fire. No injuries were reported in that incident.
Coal dust is highly combustible so Xcel workers water a plant's stored coal frequently and monitor it, Nystuen said.
In March 2008, an explosion and fire in the coal-crushing building adjacent to the 588-megawatt Allen S. King power plant in Oak Park Heights closed the plant for more than a week. One firefighter was injured while trying to extinguish the blaze.
An explosion and fire at the same plant occurred in December 2007 near a conveyor belt that feeds coal to a boiler.
Xcel Energy has proposed closing Black Dog's two remaining coal-fired boilers and converting them to modern and larger natural gas units by 2016. The proposal is pending before the Minnesota Public Utilities Commission.
If approved, the project would resemble work Xcel has done in recent years at its two aging coal plants in St. Paul and Minneapolis.
The High Bridge Plant in St. Paul and the Riverside Plant in Minneapolis have been converted to cleaner-burning combined-cycle natural gas plants as part of a metro-wide effort to reduce harmful emissions, including carbon-dioxide that has been tied to climate change.
The state is also served by Xcel's largest coal plant -- the massive 2,400-megawatt Sherco coal power plant near Becker 45 miles northwest of the Twin Cities, and two nuclear power plants.
Written by Saint Paul Pioneer Press
Courtesy of YellowBrix - YellowBrix