Before the plant could be built, city officials needed to make sure that it would be a good neighbor. “The city has been working with the company for eight years,” says Benson City Manager Rob Wolfington. Early on, a small team of city officials went to tour the three United Kingdom plants. One of the main concerns the Benson community initially had was that of the smell; poultry litter is stinky stuff. “There were no odor issues associated with those plants,” he says. “Some in the surrounding communities weren’t even aware there was a power plant using poultry litter as fuel.” Even so, the company was sensitive to Benson’s concerns. “We keep a close relationship with the community,” says Terry Walmsley, Fibrowatt’s vice president of environmental and public affairs. “We set up a citizen’s advisory panel where these types of things are discussed.”

Conventional or otherwise, a power plant must be positioned near adequate infrastructure. “It has to be near transmission lines and a substation,” Wolfington says. “Benson and its electrical infrastructure met the technical standards needed.” A 12.2 MW city power plant already in Benson helped seal the deal for Fibrominn, which chose a site adjacent to the ethanol plant. It took two years of permitting in “the land of 10,000 permits,” Wolfington quips, in addition to public hearings. Subsequently, the citizen’s panel unanimously approved locating the plant in Benson. “We spoke Fibrowatt’s language,” he says.

Litter Procurement, Odor and Process
Turkey farmers, who also produce corn, soybeans and other crops, use the turkey litter as fertilizer because of its nutritive value. However, many turkey farmers produce more litter than they can use, which can cause environmental problems if too much is spread on the fields. “Poultry litter is good to spread, but you can’t have too much of a good thing—otherwise, it’s not good,” Fraser says.

Walmsley says Fibrominn pays about $2 a ton for the turkey litter depending on its moisture content and ash characteristics. On average, poultry litter contains about 4,000 British thermal units per pound. The 55 MW Fibrominn plant, once running at full capacity, is expected to consume 2,000 to 2,500 tons of poultry litter a day. “We recognize some farmers will still want the litter for a soil amendment, that’s why we are only going after the excess litter,” Walmsley says. A majority of the feedstock required is under long-term contract with groups of poultry farmers. Approximately 50 percent of Fibrominn’s feedstock will come from the area surrounding the plant. The rest will be trucked in from about a 100-mile radius of the facility, which will be dictated by the availability of the fluctuating supply, Walmsley says. Project developers believe that in purchasing the excess litter, they are providing a valuable service to the poultry industry and the environment. It reduces the regulatory burden on the poultry farmers; lessens the risk of contaminating water supplies from too much phosphorous and nitrogen; improves biosecurity; reduces cleanout costs, and adds a couple of dollars per ton to the farmer’s bottom line. Since poultry waste originates in grains, its carbon impact in the atmosphere is low, especially when it’s compared with a coal-fired power plant.

Although odor is hard to regulate in a permit, Fibrominn operates smartly to keep the stench at bay. “The best way to avoid odor is to contain it,” Walmsley tells Biomass Magazine. Beginning when the turkey litter is picked up, the trucks are covered with tight-fitting tarps and the loads are hauled on the right routes reducing odor release significantly. Once on-site, the litter is treated for three to five days to optimize the burn. From the fuel storage hall the litter is fed into the Foster-Wheeler-designed boiler by mechanical distribution. “Poultry litter is very difficult to move and manage because of the characteristics, if you will,” Strickler says. Fifteen years of experience has taught Fibrowatt irreplaceable proprietary secrets in handling and combusting poultry litter. In moving the litter from the fuel hall to the boiler, negative pressure draws air inward to the facility. Inside air pressure is lower than it is outside, so air rushes into the plant and, therefore, doesn’t allow the odor to escape the vicinity. The incoming draft air helps the litter burn in the grate-fired boiler—a single-drum steam generator type. The high-pressure boiler steam then goes into a direct-drive steam turbine/generator combo. Urea injections treat nitrogen oxide emissions, and the flue gas undergoes additional treatment before leaving the boiler. Additional management occurs as the gases enter the scrubber and baghouse.

The resulting ash—80,000 to 100,000 tons from firing approximately 700,000 tons of biomass a year—is sold to North American Fertilizer LLC, which is adjacent to Fibrominn. “A conveyer belt takes the ash to a 60,000 or 70,000 square-foot building, where it’s stored, conditioned and made into fertilizers,” Fraser tells Biomass Magazine. “This helps restore an environmental balance—not wasting, but recycling. The ash is a great fertilizer. All farmers are chemists today. They know what the land needs. There will be no shortage of customers for the ash.”

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