1. NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC Anaerobic Digestion Overview Hawaii and Guam Energy Technology Demonstration Project Jerry Davis Senior Engineer Project Development & Finance Section 20 Sep 2011

2.  Anaerobic Digestion Overview  Current Projects  WWTP Project Characterization  Potential Navy Applications Presentation Outline National Renewable Energy Laboratory Innovation for Our Energy Future

3.  Anaerobic Digestion Overview  Current Projects  WWTP Project Characterization  Potential Navy Applications Presentation Outline National Renewable Energy Laboratory Innovation for Our Energy Future

4. ThermalBiochemical Combustion Gasification/ Plasma Pyrolysis Heat Fuel Gases (producer gas) (CO + H 2 +CH 4 ) Char, gases, aerosols (syn gas) Pretreatment Fermentation Transesterification Ethanol Biodiesel No Oxygen Partial Oxygen Excess Oxygen Digestion CH4 Energy Pathways National Renewable Energy Laboratory Innovation for Our Energy Future

5. Process Overview National Renewable Energy Laboratory Innovation for Our Energy Future In feed Reactor End User Feed Stock  Organic Food Waste  Human Waste  Oils/Fats  Wood/Paper  Agricultural Wastes  Food Processing Waste Biogas  Engine/generator  Boiler  Heater Liquids Nutrients/Fertilizer

6. Low Solids .05-3% total solids by weight  Little or no suspended solids  Single phase liquid system, readily mixed Medium Solids  3% to 12% total solids by weight  Contains suspended solids  Slurry system, can still be mixed High Solids  12 to 25% total solids by weight  “Solids-processing” system  Requires mixing General Categories of Digesters National Renewable Energy Laboratory Innovation for Our Energy Future

7. Potential Yield National Renewable Energy Laboratory Innovation for Our Energy Future Source: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex11397

8. Thermophilic:  Decomposition and biogas generation is more rapid  More sensitive to upsets and disturbances  Results in more complete destruction of pathogen Mesophilic:  Tend to be larger vessels  More “forgiving”  More common Psychrophilic  Lagoons and swamps  Slower process Temperature Range National Renewable Energy Laboratory Innovation for Our Energy Future Thermophilic (122ºF - 135ºF) Mesophilic (77ºF - 100ºF) Psychrophilic (65-70ºF)

9.  Anaerobic Digestion Overview  Current Projects  WWTP Project Characterization  Potential Navy Applications Presentation Outline National Renewable Energy Laboratory Innovation for Our Energy Future

10.  Total farm-scale projects: 156  Total regional/centralized projects: 11 Farm Based AD National Renewable Energy Laboratory Innovation for Our Energy Future Source: EPA AgStar Website

11. Wastewater Treatment Plant Projects National Renewable Energy Laboratory Innovation for Our Energy Future  1,066 WWTPs in CONUS  544 with AD  106 with AD and biogas utilization  Declining trend of biogas utilization at smaller sizes

12.  Anaerobic Digestion Overview  Current Projects  WWTP Project characterization  Potential Navy Applications Presentation Outline National Renewable Energy Laboratory Innovation for Our Energy Future

13. Key site attributes:  At least 3 million gallons per day (MGD) intake for energy recovery  Per EPA, >6.8 MGD for a CHP application WWTP: Project Characterization National Renewable Energy Laboratory Innovation for Our Energy Future

14. Project Economics National Renewable Energy Laboratory Innovation for Our Energy Future For a 6.8 MGD facility with 130 KW microturbine  Equipment costs for biogas treatment and electrical generation: $390,500  Installed cost: $564,953  Operating costs: $.022/kWh  Total electricity costs: $.03 to $.065 per kWh (depending on assumptions used to calculate avoided costs)

15.  Anaerobic Digestion Overview  Current Projects  WWTP Project characterization  Potential Navy Applications Presentation Outline National Renewable Energy Laboratory Innovation for Our Energy Future

16. WWTP facilities  Per ORNL study, about 140 WWTPs with >3 M GPD within 5 miles of federal facilities  Per NREL study, 3 Navy sites have ~3M GPD on site  Fort Kam, ~ 5.2 MGD  Puget Sound NSY, ~ 6 MGD  Apra Harbor, Guam, ~ 2.9M GPD Potential Navy Applications National Renewable Energy Laboratory Innovation for Our Energy Future

17. Jerry Davis Senior Engineer Project Development and Finance Deployment & Market Transformation National Renewable Energy Laboratory 1617 Cole Blvd, MS-302 Golden, CO 80401 303-275-3199 jerry.davis@nrel.gov Contact Info National Renewable Energy Laboratory Innovation for Our Energy Future