View
219
Download
1
Tags:
Embed Size (px)
Citation preview
Anaerobic Digestion: Turning One Man’s Trash Into Another
Man’s Treasure
January 20, 2009
Dr. Catherine Keske
Dr. Sybil Sharvelle
Recovering Manure to Produce Energy
• Benefits of Anaerobic Digesters
• How Digesters Work
• Trends and Feasibility
• Economic Issues
• How to Get Involved or Learn More
• Questions
Benefits of Anaerobic Digesters
Environmental
• Production– Soil management– Manure management– Biogas production
• Reduces environmental pollution– Water– Green house gases– Ammonia
Economic and Social
• On-farm energy generation (avoid electricity purchases)
• May sell energy to utilities
• Savings on bedding
• Sale of composted solids
• Carbon credits available
• Renewable energy certificates
• Odor control
Anaerobic Digestion: How It Works
High BOD Waste
Organics Acids
Acids CH4
High NutrientLow Odor
Waste
Anaerobic Environment
Cogeneration
Hot Water
CH4
Green Power
ADM Soybean Processing
Biodiesel Plant
Anaerobic Digester
Frito Lay
Hot Soybean Oil
Cold Soybean Oil
Hog Waste
Food Waste
Green Power
Model Project: Quadra Project in Indiana
WE Can Do This in Colorado Too!
Waste Suitablility
• Low solids content, < 14% solids
• Low inorganic content– Soil– Rocks
• Higher organic content, more energy content
Colorado – Dry Climate
Average Annual Precipitation In Colorado
Need to Find Nearby Source of Wastewater or Add Groundwater to Waste
Alternative Design - Two Stage Leachate Collection
Low MoistureManure and
Other Waste
Organics
High Organic Leachate Anaerobic Digester Methane Gas
Costs of Anaerobic Digesters
• Cost of the digester:
Approximately $1 million
Average life: 15 yrs. (Range: 10-20)
• Cost of the solids separator:
Approximately $75,000
**Key to raising profitability**
• Opportunity cost
Cost of your next best alternative
Are Digesters Profitable? “Yes…”
• Several models show profitability– Measured in cash flows associated with the
investment
• Critical to use a solids separator– Use the solids as a co-product– Bedding is the most economic use
• Larger herds lead to economies of scale
• Key element to profitability: Energy prices
“…But…Will a Digester Work for My Operation?”
• Greater than 500 head (more than 1,000 head preferred)
• Requires steady flow of manure (CAFOs)• Climate matters – the warmer the better• Must be able to use the biogas• “Community” digesters are an option
– Pipelines transport waste to central site– Could consider other facilities (e.g. food
processing)
“Yes, But…”Economic Considerations
• Majority of studies conducted in the East
• Profitability relies on carbon credits– $2 per metric ton of CO2
• “Net positive gain” may include a net gain to the environment (not necessarily a net gain to the farmer/rancher)
• Profitability critically depends upon energy prices
Want to Learn More?
• Contact Us!
• Institute for Livestock and the Environment: http://ile.colostate.edu
• USDA Producer Workshop
2/19/09 York, Nebraska
• AgStar: http://www.epa.gov/agstar/
• Colorado Governor’s Energy Office:
http://www.colorado.gov/energy/index.asp
Sponsoring feasibility studies