1. Converting Farm Waste to Energy A Primer of Anaerobic Digestion of Dairy Waste S.J. Grimberg Dept. Civil Environmental Eng. Clarkson University, Potsdam, NY

2. U.S. Energy Consumption by Source US Primary Energy Consumption

3. To get 1000 MW electrical: Method Investment needed Photovoltaic 100 km 2 @ 10% efficiency (40 sq. miles) Windmills6,660 wind turbines @ 150 kW (20 m blades) 666 wind turbines @ 1.5 MW (40 m blades) Biogas 7,143,000 cows 60,000,000 pigs 800,000,000 chickens Bioalcohol6,200 km 2 of sugar beets (2,400 sq. miles) 7,400 km 2 of potatoes (2,800 sq. miles) 16,100 km 2 of corn (6,200 sq. miles) 272,000 km 2 of wheat (104,00 sq. miles) Bio-oil 24,000 km 2 of rapeseed (9,000 sq. miles) Biomass 30,000 km 2 of wood (12,000 sq. miles) U. Mich.-Schwank Source:Gottfried Besenbruch, General Atomics

4. Anaerobic Digestion of Manure Biologically converts organic matter to biogas – 55-68% CH 4, 32-45% CO 2, trace H 2 S – Biogas can be used as a fuel source for engine generator sets or boilers. Manure management – Dairy manure produced in the U.S.: Approx. 1x10 9 tons/year Approx 4 million cows on farms with at least 300 cows – Translates to 1.5x10 8 tons manure /year – This could produce > 400 MW of electric power – Odor reductions and nutrients – Reduction in fecal coliforms and pathogens

7. U.S. Farm Digesters Mostly single farm digesters – Simple structures, often lack reliability – Poor treatment efficiency; i.e. high capital cost http://www.biogas.psu.edu/othertypesmod.html http://www.nyserda.org/programs/Environment/ag&indwastemgt.asp

8. Anaerobic Digestion Process Schematic Gas Organic Composites MS AA HAc, HPr, HBu, HVa, NH 3, CO 2, LCFA Acetate H 2 CO 2 CH 4 CO 2 CH 4 H2H2 H2OH2O Liquid Ac -, Pr -, Bu -, Va -, NH 4 +, HCO 3 -, LCFA - HCO 3 - Gas Microbes NH 3 NH 4 + Lipids Carb. Proteins Inerts Decay Growth Physiochemical Processes Biochemical Processes

10. Dairy Manure Characteristics

12. Microgy FMicgogy

13. Plug Flow Digester Example AA Dairy has been meticulous in obtaining data for more than 6 years biogas production (total & per cow) biogas composition (CO2 measurements) oil consumption (daily) electricity generated on the farm electricity sold to the grid difference between generated & sold is electricity used on the farm

21. Odor Issues Defined by VFAs 0 5000 10000 15000 20000 25000 12-May1-Jun21-Jun11-Jul31-Jul20-Aug Concentration (mg/L) Influent Date Acetic 55% Propionic 23% Isobutyric 5% Butyric 7% Isovaleric 5% Valeric 5% VFA distribution- Acetic 63% Propionic 37% Effluent Influent Effluent VFA reduced in Digester Stinkier Larger VFA molecules not found in effluent

25. Sheland Farms

30. Downtime Cost (lost revenue) By using remote smart grid protocols and monitoring, the uptime could be improved for an additional $12k per year over current operations.

31. Interesting Possibility: Co-generation w/ Food Wastes –Benefits to farmer »Increased biogas production »Improved gas quality (reduced concentrations of H 2 S »“Tipping fees” can be substantial –Benefit for Food Waste Generators »Potential Savings for disposal

36. Need for improvement NY State incentives: – Limited to farmers only – Treatment of no more than 25% non farm waste Farm digester design largely empirical. – Cannot predict mixed waste performance A system model may significantly improve operation and design process.

37. ADM1: Modeling Anaerobic Digestion For any organic material (COD basis) Potential to simulate mixed substrates Continuous flow stirred tank reactor (CSTR) Plug flow reactors can be simulated using reactors in series. Includes: 26 mass balances 19 biochemical kinetic processes 3 gas liquid transfer kinetic processes Requires numerous stoichiometric and kinetic constants Readily available data however: Waste COD Total VFA Biogas composition

38. Approach Develop a simplified input data set using the laboratory data (Page et al, 2008) Develop and validate model parameter set using laboratory and full scale steady state data using trial and error approach (Page et al, 2008). – With good results for primary parameters but could not predict reaction intermediates Develop parameter set to simulate pilot digester operated at non-steady state using detailed measurements and optimization routines

39. Pilot plant

40. COD Removal Average Influent COD: 92.7±43.0 g/L Average Effluent COD: 45.5±16.2 g/L

41. Biogas Results Average CH4 content: 57%

42. Volatile Fatty Acids

43. Conclusions Anaerobic digestion of farm waste represents a good opportunity for farmers to generate revenues and reduce energy needs Mixing dairy wastes with other wastes improves process economics Models needed that can handle mixed waste to optimize design Calibration of the wastewater model provided encouraging results. concentration, and ammonia.

44. Acknowledgements Students: – David Page, O’Brian and Gere, Syracuse, NY – Ben Durfee, Stearns and Wheler, LLC – Shawn Jones, SUNY Canton, summer research student Clarkson University – Ying Zhang, Yunghui Deng, MS students Clarkson University – Mark Venczel, Rajiv Narula, PhD students, Clarkson University – Noelle du Juvigny, Institut Polytechnique LaSalle Beauvais, France – Alex Maxwell, summer research student Clarkson University Drs. Powers, Pillay, Welsh and Thatcher North Harbor Dairy Drs. Christian Rosen, Darko Vrecko and Ulf Jeppsson (all Lund University) for providing the Matlab ADM1 code. Funding Sources: USDA, DOE, New York Ag and Markets, NYSERDA

45. Thank you for listening