Currently, Northern States Power has no additional emissions controls planned for Bay Front Boiler #5 and plans to cease coal combustion at that boiler by Jan. 1, 2015, in order to comply with the Wisconsin mercury reduction rule.
“The boiler will continue to available for operation, but will burn only natural gas,” said the Xcel Energy (NYSE: XEL) subsidiary in a brief Oct. 25 filing at the Wisconsin Public Service Commission.
The filing was to answer a commission follow-up question related to a Sept. 12 application for permission to install a baghouse and activated carbon injection equipment for emissions on boilers #1 and #2 at the coal- and biomass-fired Bay Front plant in Ashland, Wisc. These new controls would reduce particulate matter and mercury emissions from boilers #1 and #2 and ensure the utility achieves compliance with the U.S. Environmental Protection Agency’s National Emission Standards for Hazardous Air Pollutants for Major Sources: Industrial, Commercial and Institutional Boilers and Process Heaters.
Also on Oct. 25, the utility filed with the commission a 2006-2011 rundown of fuel burn at boilers #1, #2 and #5. All three boilers had a gradually reduced level of coal burn during the period, though the 2011 coal burn picked a bit for both, with #1 burning 6,014 tons of coal in 2011 and #2 burning 12,906 tons. Both of these units burned a lot of wood, railroad ties and some natural gas during the period.
Boiler #5 burned 31,827 tons of coal in 2011, down from 103,070 tons as recently as 2007. It burned petroleum coke in the 2006-2009 period, but none in either 2010 or 2011. Its only other fuel during the period was natural gas.
Bay Front is located on about 50 acres of land on the shores of Chequamegon Bay of Lake Superior in Ashland, Wisc. The plant originally began operation in 1916. By 1960, it operated five boilers and six turbines. Two of the boilers and three of the turbines have since been retired. The three remaining boilers feed into a combined steam header system that can support three turbine-generator sets. Of the remaining turbine/generator sets, #4 can produce 22 MW and came into service in 1949, #5 can produce 22 MW and came into service in 1952, and #6 can produce 30 MW and was placed in service in 1957.
Biomass is currently the primary fuel used in boilers #1 and #2. The new emissions project will involve installation of a pulse jet baghouse on boilers #1 and #2, as well as a compressed air system, ductwork and supports, and fly ash handling equipment. The activated carbon injection system will consist of a material storage silo, bin vent, rotary discharge valve and associated piping. By installing this new equipment, the utility will be able to continue to use biomass as the primary fuel in these boilers. Installation activities for these new systems are scheduled for the winter of 2012-2013, with completion in March 2014.