Xcel Energy to switch third boiler to biomass

By Susanne Retka Schill
Xcel Energy is on track to convert the last remaining coal-fired unit at its Bay Front Power Plant in Ashland, Wis., to a biomass gasification system. The conversion, estimated to cost between $55 million and $70 million, will allow the facility to use 100 percent biomass in all three boilers.

Xcel Energy announced in October that it will submit an application to the Public Service Commission of Wisconsin. If approved, the company said it expects the engineering, design and construction work on the third boiler to begin in 2010 and finish in late 2012.

The gasification system will convert biomass to synthesis gas to be used as fuel in the boiler. Compared with coal, the biomass boiler is expected to reduce emissions of nitrogen oxides by 50 percent, sulfur dioxides by more than 85 percent and particulate matter by 90 percent, the company said.

The Bay Front Power Plant has been burning wood waste to generate electricity since 1979, using more than 4 million tons during its lifetime. The biomass used at Bay Front is primarily wood waste from area forest harvest operations supplied by local independent contractors. According to Xcel Energy, the plant currently uses just over 200,000 tons of wood waste each year.

When the project is complete, the plant will use an additional 185,000 to 250,000 tons of wood waste annually. The boilers at the Bay Front facility can burn a variety of things, including wood waste, railroad ties, discarded tires and natural gas, to produce steam to drive turbine generators that produce electricity, the company said. The power plant has a $20 million annual economic impact on a six-county region around Ashland.

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 of Xcel Energy.

An April 2007 report by the Energy Center of Wisconsin determined that forests within 50 miles of the plant could support additional biomass removal without adverse impacts to the local ecosystem. An estimated 860,000 tons of harvest residues are generated each year. 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, according to the report.