On-Farm Gasification Unit Turns Straw Into Electricity

On-Farm Gasification Unit Turns Straw Into Electricity ENERGY Alternative Fuels 32-3-4 Early results suggest an on-farm gasifier developed in Washington State could make excess crop residue more valuable than ever. Jack Zimmer is the project manager for Farm Power, a non profit organization overseeing the gasifier project. He says the second-generation unit should be ready for start up about mid May with hopes for a commercial unit by fall. "We successfully operated a prototype unit for 100 hours and then engineered new components based on that test," says Zimmer. "The idea is to use finely chopped straw off the field without baling or pelletizing." The 27-ft. tall, 12-in. dia. tube within a tube is built from stainless steel pipe. It's designed to use pyrolysis to spin straw and other biomass material into carbon gold. Temperatures of 1,800 degrees will produce hydrocarbon gases that can be used to replace up to 80 percent of the diesel fuel needed to power an electrical generator. Straw stored in a neighboring shed is blown to the top of the tube. As it falls down the length of the tube, it's turned into gas, with the ashes removed at the bottom for spreading back on the fields. "It will produce enough fuel to power itself and produce 350 kW of electricity to feed onto the grid," says Zimmer. "The nitrogen is gone, but the potash, phosphate and other trace minerals will be returned to the fields." The design is based on a process for coal gasification. Cast iron components were used for bluegrass gasification at the University of Wyoming, but they wouldn't stand up to the higher temperatures needed for biomass gasification. It was also more than four times heavier than the stainless steel. The prototype unit was designed and built with a Federal research grant and constructed on the Larry Gady farm in eastern Washington. The blue grass seed producer has high hopes for the unit's success. "We used to burn our bluegrass straw, but have been unable to do so for the past 13 years," he says. "This gasifier could revolutionize the use of crop byproducts like that straw." Although costs for developing the gasifer may total more than a million dollars, the basic design is simple, says Gady. "It's so simple that you look at it and wonder what it is," he says. The real beauty of the gasifer is its on-farm design, suggests Gary Banowetz, research leader, USDA Ag Research Service, Corvallis, Oregon. He's working with the project to determine how much straw can be taken from surrounding fields without mining nutrients or encouraging erosion. He is also looking at the nutrient value of the ash and how to apply it. Most biomass-to-energy conversion systems require the straw or other material be baled and transported to a central facility. Even in corn country, economics are doubtful. In the West, it's an even bigger issue. "In a lot of places we can only take off a ton per acre, and fields are scattered," says Banowetz. He estimates a commercial Farm Power gasifier will likely cost around $350,000 and should pay for itself in about three years. In addition to generating electricity, the gasses produced by the unit can also be turned into a liquid fuel at the rate of 60 gal./ton of straw. Contact: FARM SHOW Followup, Gary Banowetz, USDA ARS, 3450 SW Campus Way, Corvallis, Oregon 97331 (ph 541 738-4125; fax 541 738-4160; gary. banowetz @ars.usda.gov) or Jack Zimmer, Farm Power (ph 208 772-7294; seedguys@verizon.net).

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