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Oregon’s Methane Project - Experience and Potential Mike Gamroth Oregon State University Dept. of Animal Sciences.

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Presentation on theme: "Oregon’s Methane Project - Experience and Potential Mike Gamroth Oregon State University Dept. of Animal Sciences."— Presentation transcript:

1 Oregon’s Methane Project - Experience and Potential Mike Gamroth Oregon State University Dept. of Animal Sciences

2 The process Anaerobic digestion – like the rumen –Longer retention Methane collection Methane use –Heat, hot water –Combustion engine electricity “Methane digester”

3 Basic concepts Decomposition of organic material Oxygen-free environment Numerous strains of microorganisms Biogas –Methane 50-80% –CO % –Other gases

4 Ambient temperature –Covered lagoon –Lowest output Mesophilic –Around 100º F –More forgiving Thermophilic –Highest output, lower retention time

5 Digester types Plug flow –Suited to scraped manure –Most common on dairies –Long rectangular tanks –Heat added, in-ground or insulated –Retention time (RT) 15 to 20 days

6 Digester types Complete mix –Typically upright round tanks –Benefits from regular feeding –Can handle “wetter” manure –When co-digesting, mixing important

7 Digester types Covered lagoon –Lowest cost, simplest to operate –Best suited to warm climates, wet manure –Lowest gas output –Often will be “seasonal”

8 Digester types Biofilm –Can augment any digester –A place for bacterial activity –Reduces retention time

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10 Economics 101 A thrifty digester system can payback in 7 to 10 years –Initial cost –Operation costs –Value of energy, tax credits –Other benefits – odor control, solids sales

11 Benefits of digestion Generate energy from biomass Odor reduction More readily available nitrogen Pathogen reduction $65$68$80$83

12 Why there aren’t more… Poor design Lack of skills, time Excessive maintenance, operation time Diminishing returns over time Lack of interest Out of business EPA and Meyer, et al

13 Keys to success Know your manure quality Match the digester technology with the manure Select a tested design and keep it simple Take advantage of incentives Monitor the system daily Line up operation and maintenance backup

14 Resources Our project: –Energy Trust of Oregon –Oregon Beef Council –Oregon Dairy Farmers Association Amanda Green (360) Amanda Green (360)

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16 A partnership of Cal-gon Farms and Portland General Electric

17 The system Scraped manure Piston pump to feed digester Digester effluent through a screw- press screen Liquids stored in lagoon Solids in covered bunker

18 Uses Lagoon liquids mixed with water and irrigated onto field corn Solids are sold off the farm and used as bedding Recycling lagoon liquids through separator when not used for digester

19 Research project Questions about the farm’s nutrient balance Questions about the start-up and stabilization of the digester Received money from a grant program to sample the digester during start-up and for a two month period during operation Evaluate solids as a soil amendment

20 Electrical Output Generation Record (based on PGE bills) Cal-Gon Farms Biogas Project /3/ /27/ /29/ /28/ /29/ /30/ /30/2002 Avg kWh/day# DayskWh Ending Svc Date

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22 Basic results Lb. / 1000 gallons DM %NPK CFU/100 ml E. coli Raw manure mill. Digester effluent mill. Solids /t2.4/t3.7/t

23 Exporting solids to reduce nutrient loading Lb./cow-year (3.5 ton/cow) NPK Avg. separated solids Bernie’s separated solids Bernie’s lagoon solids Average of 51 separators, Willamette Valley, 1995

24 Solids plots

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26 DAF separation TSTSS Raw1.9 Sludge3.3 Effluent %+ P removal


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