Xcel Energy plans to convert coal unit to biomass

By Ryan C. Christiansen
Web exclusive posted Oct. 3, 2008 at 9:58 a.m. CST

Xcel Energy plans to spend $55 million to $70 million to convert the last remaining coal-fired unit at its Bay Front Power Plant in Ashland, Wis., to a biomass gasification system. The conversion will allow the facility to use 100 percent biomass in all three boilers.

The gasification system will convert biomass to syngas, which burns cleaner with far fewer emissions than coal. The syngas will be used as fuel for the unit's boiler. The project is expected reduce emissions of nitrogen oxides by 50 percent, sulfur dioxides by more than 85 percent and particulate matter by 90 percent, the company said. Xcel Energy recently announced that it will submit an application to the Public Service Commission of Wisconsin for its approval of the project. If approved, the company said it expects the engineering, design and construction work to begin in 2010 and the unit could be operational in late 2012.

The Bay Front Power Plant has been burning waste wood to generate electricity since 1979, the company said, and the plant has burned over 4 million tons of waste wood to generate power during its lifetime. The biomass used at Bay Front is primarily waste wood from area forest harvest operations and local independent contractors who secure the waste wood and transport it to the plant. According to Xcel Energy the plant currently uses just over 200,000 tons of waste wood each year. When the project is complete, the plant will use an additional 185,000 to 250,000 tons per year and will be able to generate enough electricity to serve 40,000 homes. Through its purchases of waste wood and related services, the company said the plant has a $20 million annual economic impact on a six-county region around Ashland.

An April 2007 study with the Energy Center of Wisconsin determined that forests within 50 miles of the plant, including those in the Wisconsin counties of Ashland, Bayfield, Douglas, Iron, Sawyer and in Gogebic County, Mich., could support the additional biomass removal without adverse impacts to the local ecosystem. According to the report, the U.S. Forest Service North Central Station estimates that about 860,000 tons of harvest residues, including 121,000 tons from softwoods and 739,000 tons from hardwoods, are generated in the region annually. Most forest administrators and owner representatives indicated that additional removal and chipping of residues, especially tree tops, would be a welcome activity for their forest operations, the report stated.

The three boilers at the Bay Front facility can burn a variety of fuels, including waste wood, railroad ties, discarded tires, and natural gas, to produce steam to drive three turbine generators to produce electricity, the company said.

Xcel Energy currently generates 11 percent of its electricity in Wisconsin from renewable resources and plans to reduce carbon dioxide by 22 percent from 2005 levels in its Midwest generation system by 2020, according to Dick Kelly, president and chief executive officer for Xcel Energy.