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What’s Ahead for Biomass The pieces are all in place to make cellulosic biomass a viable part of the U.S. energy security puzzle, according to Chris Zygarlicke, deputy associate director for research at the Energy & Environmental Research Center in Grand Forks, N.D. He spoke about the current state of biomass and where it’s headed at Biomass ’09. Cellulosic biomass meets the carbon dioxide emission life-cycle targets, it’s sustainable, has growing incentives and support, has an established window for demonstration of viable technologies for production and conversion and is gathering significant business investment, he said. Success will depend on government policies, incentives, the development of sustainable biomass feedstocks and proving new conversion technologies in nearcommercial-scale biorefineries and bioenergy systems, he added. Cellulosic biomass must become a major, if not the primary, source for biobased fuels, he said. Oil-bearing, non-food crops such as jatropha and oil from new strains of algae appear to be on the verge of becoming important resources for liquid biofuels.
Zygarlicke addressed policy and incentives, feedstocks, biofuels and bioenergy. “Policy and legislation are crucial in moving forward,” he said, citing the Energy Independence & Security Act of 2007, the American Recovery and Reinvestment Act of 2009, which provided $72 billion for clean energy projects and $20 million in clean energy tax incentives, and the 2009 Climate Bill. It could be the first legislation to limit carbon dioxide, he said of the Climate Bill. “This will be a huge factor, one way or the other.” Biomass feedstock availability and sustainability is largely dependent upon commodity crop prices, he said. Biomass is also highly susceptible to climate and climate change. Right now, fewer than 1 billion dry tons of biomass are available, but that number could climb to just over 1 billion with modest changes and higher yields, he showed in a bar graph. Feedstocks can include agricultural and wood residues, municipal solid waste, triacylglycerides and energy crops. “The days of corn ethanol-only are gone,” he said as he began to discuss biofuels. Emerging thermal and fermentation tech-
nologies are moving along in the cellulosic biomass to biofuels sector. In the area of bioenergy, the U.S. has few incentives for large utility cofiring of biomass, Zygarlicke said. “But we are starting to Chris Zygarlicke see a positive slope.” deputy associate Distributed biomass director, EERC gasification is one good solution, he said. It requires low water consumption and simple gas cleanup, among other positive aspects. In conclusion, Zygarlicke took the crowd down the biomass road before us. Sustainable feedstocks must not compete with food, and agricultural processes must minimize water consumption, he said. Opportunities abound for commercialization. “Technology has never been more poised, I don’t think, to determine a future for renewable biomass resources,” he said.
Agricultural Anaerobic Digestion on the Rise National trends in anaerobic digestion of agricultural manure have increased between 2000 and 2007 from fewer than 50 million kilowatt hours (kWh) per year to more than 200 million kWh per year, according to Dan Stepan, senior research manager with the Energy & Environmental Resource Center in Grand Forks, N.D., and a presenter at the organization’s Biomass ’09. A key niche for the process is converting biomass materials to methane gas. In the U.S. this year, 98 anaerobic digesters are using dairy farm manure, 19 use hog manure, three use manure from caged layers, two from ducks and one each from boilers, beef and mixed manure, Stepan told the crowd. “But there’s still potentially a large untapped resource,” he said. The potential biogas-to-energy production from swine farms is more than 3.1 billion kWh per year, he showed in a graph, and the potential from dairy farms is more than 3.3 billion. About half of the country’s wastewater treatment facilities have anaerobic digesters, but only 19 percent use the biogas, Stepan said. Anaerobic digestion is an old technology. “By ‘old,’ I mean really old,” Stepan said. The process was used in Assyria in the 10th century to heat bath water and has been used in the U.S. for the past 100 years to treat municipal and industrial waste and 44 BIOMASS MAGAZINE 9|2009
wastewaters. According to Stepan, it’s an attractive solution for several reasons: the high water content of many biomass materials makes them impractical for combustion; drying costs to achieve a combustible condition exceed the value of energy recovered by combustion; and anaerobic digestion produces a valuable fuel gas. But the process has challenges when it comes to processing different feedstocks, Stepan said. “Siloxanes are a unique attribute of municipally-derived biogas,” he said. The volatile silicon-based compound is used today in personal care products and paints, among other products. It can be found in municipal digester and landfill biogas at high concentrations and forms silica, or glass, when it’s combusted. Accumulated silica damages engine cylinders, turbine blades, exhaust heat exchangers and piping. The typical processes to control Siloxane include refrigeration at less than 40 degrees Fahrenheit followed by activated carbon; advanced refrigeration to minus 25 degrees F; and selexol liquid absorption, Stepan said. Hydrogen sulfide is another gas produced during anaerobic digestion and control techniques include chemical, physical and biological processes. EERC has developed a proprietary sulfide control process with a blend of ingredients that minimizes
the production of hydrogen sulfide, kills the bacteria that produces it, and scavenges any that is produced. It also possesses long-term control effects and comes at a low cost, Stepan said. EERC will demonstrate its sulfide control technology capabilities in anaerobic digestion of dairy manure on the Haubenschild Farm Dairy in Princeton, Minn. The project will take place over the next 2½ years and consists of three phases: lab screening experiments, bench-scale testing and pilot-scale demonstration, Stepan said. Lab screening experiments are taking place now and bench-scale digester design activities have been initiated. Haubenschild Farm has a 500,000-gallon digester that uses the manure from 850 cows, Stepan said. The process produces 72,500 cubic feet per day of biogas with a methane content of 60 percent. The combined-heat-and-power unit, made with a diesel engine and an electrical generator, generates enough electricity for the farm’s operations plus 60 homes and enough heat for the digester and all other buildings on the farm, Stepan said. The digested manure is used as fertilizer, which saves an estimated $40,000 a year, he added.