Landfill Lube A 30-foot flame once burned off methane seeping from the 500-acre Marathon County landfill near Ringle, Wis. Now the gaseous output of garbage decomposition converts sawdust into pellet fuel, heats the landfill power plant and generates electricity for 1,200 homes. For nearly nine years, Fiber Recovery Inc. has dried waste from a Wausau, Wis., area paper mill, converting it to wood pellets and selling them back for boiler fuel, says Scott Pempek, manager of the Fiber Recovery plant now located in the landfill. Then the recycling company recognized the potential of converting landfill gas to electricity to dry wood waste, heat the plant and sell for added revenue. Two years ago, in a unique partnership with the county, Fiber Recovery began capturing the landfill’s methane gas and running it through a complex scrubbing process. The resulting biogas powers three Caterpillar 3516 engines that generate power for sale to Wisconsin Public Service, Pempek says. In addition, systems capture exhaust gas from the 16-cylinder engines to dry mill waste and thermal energy from engine-jacket coolant water to heat the building. Amid the roar of three huge engines generating electricity from landfill biogas, CHS Certified Energy Specialist Jeff Tobin, left, checks performance monitors with Scott Pempek, Fiber Recovery Inc. plant manager. Wisconsin is home to about 20 farm-based methane digesters and more are in the pipe-line. National policy debate on sustainability and greenhouse-gas issues has boosted interest in digester technology. The Crave brothers — Charles, George, Thomas and Mark — operated a digester for two years before recently adding a second one in partnership with Clear Horizons, a Wisconsin firm specializing in biogas energy systems. The company owns and operates the farm’s two anaerobic (oxygen-free) digesters, controlled by computer from its Mil-waukee office an hour east. Karl Crave, Charles’ son, manages the digesters for Clear Horizons. “We planned the digester expansion from the beginning of our growth process,” says Charles, explaining every step of growth is carefully considered for years before moving forward. The family benefits from the arrangement, he points out, since it doesn’t have additional capital tied up in digester technology. Plus the farm has access to the resulting stabilized low-phosphorous, low-odor liquid fertilizer. Stopping Engine Abuse To prepare biogas for powering the gen-erators, scrubbers must remove siloxane, hydrogen sulfide, halides and other compo-nents of landfill gas that are highly volatile and tough on engine valves. Employees closely monitor and maintain siloxane and methane levels within acceptable ranges. Still, the engines need superior lubrica-tion to combat residual contaminants. For help, Pempek turns to Jeff Tobin, certified energy specialist (CES) for Customer One, a cooperative based at Marathon, Wis., who was referred by a construction company working at the landfill. From the Cenex Lubricants Terminal that Customer One uses to serve much of the state, Tobin supplies the landfill plant with bulk totes of Cenex ® NGEO engine oil geared for biogas and landfill gas engine uses. Pempek and Tobin, with help from Bob Theisen of CHS energy technical services, take oil samples every 250 hours for Lube Scan ® lab analyses. “Scott believes in timely maintenance,” says Tobin. “We’ve had excellent life from the oil,” adds Pempek, who runs NGEO in his land-fill engines 700 hours or more, depending on LubeScan results. Co-op Customer The family is a long-time energy, agronomy and feed customer of United Cooperative, based at Beaver Dam, Wis. Among the lubricants used in the family’s businesses is Cenex ® brand NGEO engine oil, specially formulated for biogas engines to cope with methane’s acidity. To handle the farm's expanded digester capac-ity, Clear Horizons installed a new natural gas engine/generator set made by GE’s Europe-based Jenbacher division. The Wisconsin company called in Bob Theisen, manager of CHS energy technical services, to run a field test of Cenex NGEO in the new engine to gain manufacturer certification. Theisen says startup and the first 2,000 hours of the 10,000-hour trial went flawlessly. He expects the Cenex biogas lubricant, a leader in the methane-digester field, to continue to do well since it has already proved its worth under similarly tough ag and industrial conditions. •• LEARN MORE •• Visit www.cenex.com to read more about Cenex ® lubricants. 24 July/August 2009 WWW.CHSINC.COM