Black Dog Generating Station

Location: Burnsville, Minn. on the Minnesota River.

Plant Description: Black Dog is a coal- and gas-fired generating station, located on the Minnesota River just south of the Twin Cities.

The original Unit 1 boiler/turbine and the Unit 2 boiler, installed in the 1950s and fired on coal, recently were replaced with a natural gas combined-cycle unit (Unit 5), which includes a natural gas-fired turbine-generator combined with a heat recovery steam generator. Exhaust heat from Unit 5 powers the Unit 2 steam turbine. The repowering project, completed in summer 2002, boosts output from the two original units by more than 100 megawatts, and results in greater operating efficiency and cleaner power production.

Units 3 and 4 are dual-fuel boilers with steam turbines that continue to utilize coal as the primary fuel. Natural gas is the backup or topping fuel used to obtain maximum generation for both units.

Power Production Capability: (In-Service Dates) 538 megawatts: Unit 2 – 98 MW (1987); Unit 3 – 108 MW (1955); Unit 4 – 170 MW (1960); Units 5 (2002) – 162 MW.

Fuel Sources: Low-sulfur western coal and natural gas

Black Dog takes its name from the Black Dog band of Sioux - or Dakotah - and their leader Chief Black Dog, who settled an area on the south bank of the Minnesota River around 1750. The settlement was the oldest Mdewakanton tribe in the area.

All four original Black Dog units were built in the 1950s, and by 1960 Black Dog was the second largest base load plant in what was then the Northern States Power system, a predecessor to Xcel Energy. In 2002, with the addition of the new combined cycle unit, the plant regained its status as the second largest fossil fueled plant in Xcel Energy’s North region. Black Dog’s coal units generate power 24 hours a day, seven days a week. The natural gas combined cycle unit is designed to provide intermediate generation during higher load periods.

Black Dog is located in the Minnesota River Valley, also home to variety of waterfowl and other wildlife. A good vantage point to view migrating waterfowl is along Black Dog Road between Interstate Highway 35W and Cedar Avenue. Xcel Energy owns about 1,500 acres around the Black Dog cooling ponds that it leases to the U.S. Fish and Wildlife Service so it can maintain a preserve. Black Dog Preserve includes rare plant families more than 4,000 years old, along with thousands of waterfowl and songbirds, hawks, squirrels, gophers, chipmunks, foxes, beaver, raccoons, deer and mink.

Black Dog's use of western coal limits sulfur emissions and the plant employs electrostatic precipitators to remove fly ash particulate from Units 3 and 4. Precipitators act on the principle of static electricity attracting dust. In this case, the dust is fly ash particles. Fly ash in exhaust gases passes through an electric field, where the particles receive a negative charge. Positively charged plates attract and collect the negatively charged ash particles. Hammers that periodically strike the plates knock fly ash into hoppers. Virtually all of the ash that's captured is used for construction purposes in concrete and road base material.

New Unit 5 operates on natural gas. It utilizes state-of-the-art technology for controlling nitrogen oxide (NOx) releases. Emissions from the new unit are running below permit levels.

Plant management actively partners with the city of Burnsville in the upkeep of Minnesota River frontage. The plant also is partnering with the Burnsville school system in a mentoring program for technically inclined students. Plant employees are involved in various community activities, such as Meals on Wheels and athletic programs.