Biomass Gasification System/SOURCE: XCEL ENERGY

The gasification technology mimics natural gas combustion characteristics, he says. The project’s $58 million price tag covers the cost of the gasifier equipment and some minor changes to the boiler to maximize heat recovery, as well as new fuel handling equipment such as another hydraulic truck dumper and conveyer belts to move the fuel to its storage area.

According to Donovan, the power plant will not see a decrease in power production post-conversion. “Currently, boilers one and two produce approximately 20 megawatts (MW) of electricity from 100 percent biomass,” he says. “Boiler number five, when burning 100 percent natural gas, it can produce about 32 MW; realistically about 28 MW on a consistent basis. With coal, we’re at 20 MW, and when we convert to biomass, we’ll replace that 20 MW.”

Xcel Energy expects it will need an additional 40 trucks per day to deliver fuel to the plant, according to Donovan. “It really depends on how much material the trucks bring in, but we expect each to load 20 to 25 tons,” he says.

Once delivered, the prepared biomass will be unloaded using Xcel Energy’s existing systems to put it into a storage pile or directly into a storage bin for combustion. “Once it comes through the gate, it’s very similar to how you’d handle coal or any other solid material,” Donovan points out.

Cost Factors
Xcel Energy has projected biomass fuel costs to be cheaper than coal, if current prices can be maintained. “This plant is small, and it has specific fuel requirements,” Donovan says. “We should be competitive with coal prices at that plant, and the analysis we’ve done so far is based on what it’s going to cost us to make the conversion and what kind of a rate impact that will have on our electric customers.”

Despite the cost benefits, Donovan admits the fuel procurement process has been long and arduous. “We have no rail access, and even if we did it is such a small plant; we couldn’t get the economies of scale for fuel delivery with rail,” he adds.

Biomass for the plant is trucked in from Duluth, Minn., Superior, Wis., or a freighter loads it to a storage dock, where Xcel Energy trucks it to the plant. “It’s a very labor-intensive process,” Donovan says.

Xcel Energy hopes to gain project approval from the PSCW in the fall, and has similar applications in Wisconsin and in North Dakota and Minnesota. “Because of the way our system operates, we share costs across a five-state jurisdiction,” he explains. “In Xcel’s northern territory, any investment made in Wisconsin is paid for by customers in North Dakota,
South Dakota, Michigan and Minnesota, and vice versa. We share all costs, and dispatch all of our generation resources as a system.”

Engineering, design and construction work is expected to begin in 2010, so the new Bay Front Power Plant could be operational in late 2012. By this time, the plant will be less than five years away from its 100th birthday, and will venture into a new century of life with a clean slate.

Anna Austin is a Biomass Magazine associate editor. Reach her at aaustin@bbiinternational.com or (701) 738-4968.

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