Methane Gas Capture: two case studies

1. Methane Gas Capture:two case studies Ben Teague Mississippi Technology Alliance/ Mississippi Alternative Energy Enterprise

2. Methane Gas Capture General Overview

3. The Anaerobic Process to Make Biogas • In the absence of oxygen naturally occurring bacteria will break down manure • The break down and conversion to methane occurs in four basic steps. • Hydrolysis • Acidogenesis • Acetogenesis • Methanogenesis • The final stage methanogensis is the actual break down of the immediate compounds to methane • Biogas is usually composed of 55-75 percent methane. Carbon Dioxide and Hydrogen Sulfide make up the bulk of the remainder.

4. Types of Anaerobic Digesters

5. Three Main Types of Digester Design Options • Complete Mix (CSTR) – fully homogeneous contents • Plug Flow – mimics a series of laterally mixed units • Lagoon – energy recovery from treatment oriented design

6. Other Digester Types • Batch- fed reactor, such as the anaerobic sequential batch reactor (ASBR) • Temperature- phased anaerobic digester (TPAD) • Suspended particle reactor • Anaerobic filter reactor • Upflow solids reactor • Continuously stirred tank reactor with solids recycle • Upflow anaerobic sludge blanket reactor • Anaerobic pump digester • Fluidized- and expanded- bed reactors • Fixed film anaerobic digester AgSTAR August 2002 Haubenschild Farms Anaerobic Digester Final Report

7. Biogas Water Water . Solids Barn Manure Slurry Flash Mix CSTR Digestor Separator Complete Mix Digester • Contents kept mixed or periodically mixed • Batch or semi-batch operation • Mixing accomplished using mixer or pump • High rate and extent of biogas production • Complex solids handling • Comparatively expensive • Common with smaller systems • Lower L/S ratios (more water [+ & -]) • High level of mechanical wear

8. Plug Flow Digester Plug Transport Water . Solids Barn Manure Separator • PROS • Low maintenance • Batch or semi-batch operation • Rapid recovery time/ low retention time needed • Can be used effectively in multiple climates • CONS • Comparatively expensive • Smaller reactor volume • Labor intensive material handling issues Not 100% Necessary (Slurry in Digester) Biogas Mixing tank PF Digestor

9. Water . Solids Barn Manure Separator Covered Lagoon • PROS • Least Expensive • Low Maintenance • Material handling • Can handle low solids manure • CONS • Land availability • Efficient only in high temp climates • High retention time needed b/c of low • low efficiency and liquid amounts Biogas

10. Typical Digester System Design

11. IC Engine Liquid Fertilizer Cultured Growth To Grid Biogas Storage . Gas Compressor Heat Recovery Milking Parlor or other market Heaters Potential Protein Recovery Biogas Electricity Generation Barn Digestor Heating (winter) Screen Digestor Plant Bedding Liquids Storage Tank/ Lagoon Liquid Solids Separator Compost

12. General Benefits of a Digester System • Odor Control • Cash savings • Reduced risk of being subject to legal action • Renewable Energy Production • Heat • Electricity • Pathogen Reduction • Greenhouse gas reduction • Reduction in TOD (Total Oxygen Demand)

13. Two Case Studies Swine and Dairy

14. Two Sites in Mississippi • The Land Water Timber Resource Board has funded Mississippi Alterative Energy Enterprise (MAEE) to construct two Methane gas capture systems. • Swine system located in Montpelier, MS • Dairy system located in Forest, MS

16. Dairy System • Dairy manure characteristics matches well with a plug flow manure. • Due to the high solid content dairy manure can easily be scraped versus flushed • A scraping system adds no or very little water into the system. Thus a plug flow system is common. • However, this system at Forest is a hybrid system. It utilizes a high pressure low volume flushing system. • The manure will enter the digester at about 3-6% solids.

17. Dairy Methane Gas Capture System • Location: Mills Dairy in Forest, MS • Farmer: Quentin Mills • Total Project Cost ~$750,000-$800,000 • Digester system cost: ~$282,000 • Gas Use: Heating and Electricity • Heating – direct use • Electricity- through methane capable genset • Estimated Annual Power Savings • Farmer: $25,000 • Construction is due to be completed by April 22, 2004. (Earth Day) A tour will be scheduled in the afternoon.

18. Why Here? Why Now? • Mills Dairy (a 400 head dairy) • Within the range of successful digester farms • Accurate representation of an average to high number Mississippi Farm. • Farm Bureau pointed us toward the Mills Dairy because they were transitioning from pasture to a confined operation • This transition time was a perfect penetration point due to capital expenditures, construction economies of scale and need for manure management changes. (lagoon would not be large enough)

19. Offset purchased Propane methane Electricity to operate system, excess to Grid Genset Barns Anaerobic Digestion Clear Water Existing Lagoon Solids Separator Equalization Basin Compost Recirculation for barn flushing Dairy System Schematic Spray irrigation

24. Dairy Activities to Date • Educated the farmer on Technology • Finalized working agreement issues • Refined planning assumptions • Executed project contract • Visited Florida Dairies & UF AD facility • Defined communications/reporting requirements • Concept design Dairy (design/waste treatment plant layout) • Identified permit issues • Preliminary engineering & permit package • Site Preparation

25. Dairy Activities to Date Cont… • Submit permit package • Finalize design documents (09-11-03) • Finalize equipment/contractors agreements • Receive permit (90 days) • Pour barn concrete (meeting 09-11-03) • Procure equipment & materials • Begin construction

27. Swine Methane Gas Capture SystemReview • Location: M&N Nursery in Montpelier, MS • Farmer: Mike Shinn • LWTRB Grant: $114,000 • Prestage has donated $20,000 • Gas Use: Heating and Electricity • Heating – direct use • Electricity- through methane capable genset • Estimated Annual Savings • Farmer: $11,587 • Prestage:$3,755 (see next slide) • 8 barns = ~ 6,500 hogs at an average weight of 38 pounds per hog. (grown from 12-50lbs) • M&N is paying ~ 7.5 cents per kwh for power and consuming ~ 88,685 kwh per year. In 2000 M&N paid $6,659 • Because M&N is a Prestage grower they have a capped cost of 45 cent per gallon of propane. However the total propane cost in 2000 was $16,614

28. Swine System Savings (Total Savings $15,343) ($.85/ gal $.07 retail $.02 sell back) retail actual = .075 per kwh

29. M&N Swine System Existing lagoon Biogas for direct burn barn Covered lagoon biogas Genset Used on farm IC Engine Liquid Fertilizer To the grid Cultured Growth Liquids pumped from lagoon

30. Existing Lagoon BARNS Anaerobic Digester Swine Schematic genset Flare

31. Swine System • Technology- This system utilizes a covered lagoon approach • Markets for Biogas- The biogas will fill all heating needs and will then flow over to a generator to supplement or replace power needs. • Construction- Construction should be complete by April 22,2004 • Paybacks was based on Propane cost offset and on gas production. However, assuming average production and $1.00 per gallon of propane cost the system should be able to pay itself back within 5-6 years simple payback

32. Swine Activities to Date • Many necessary “back office” issues have been completed. These activities pave the way for construction activities • Meeting with DEQ to determine possible permitting • Construction contracts in draft form • Feasibility study performed earlier by Phil Badger • Detailed financial models produced • Investment secured from Prestage Farms. (09-12-03)

33. Swine Activities to Date cont… • Soil samples have been taken for digester site to determine necessity for clay lining and amount of clay needed • Educated participating farmer on the system • Complete working agreement and contracts • Identify planning assumption • Engineering blueprints • Finalize equipment/ contractors agreements • Procure all equipment and materials • Site Preparation

34. Key Closing Thoughts • Economics or regulatory demands will drive the proliferation of these systems in the Southeast. • Types of manure match well with certain technologies at this point; however, the lines are being blurred by new technologies. • A predetermined market for power or biogas product is key to the economic viability • Relationship with the Local Power Provider is key

35. Questions ?