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Source Separated Organic Materials Anaerobic Digestion Feasibility Study. Prepared for Ramsey/Washington Counties Resource Recovery Project Board And the St Paul Port Authority By Foth Infrastructure & Environment. Scope. Review AD processes & current development
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Source Separated Organic Materials Anaerobic Digestion Feasibility Study Prepared for Ramsey/Washington Counties Resource Recovery Project Board And the St Paul Port Authority By Foth Infrastructure & Environment
Scope • Review AD processes & current development • Examples of large scale AD plants • Option for biogas generation and use • Energy market status • Availability/composition of SSOM in metro area • Facility Design Considerations • Permitting and Environmental Considerations • Economic Analysis • Schedule
Definitions • Process to degrade organic material in the absence of oxygen. • Microorganisms transforming degradable organics into water, carbon dioxide, and methane • Degradable portion forms biogas • Non-degradable portion forms digestate
State of the Technology • Most facilities used on MSW feedstocks are located in Europe • Anaerobic digestion of MSW sources not yet common in US • Report examined process types, technology suppliers, and selected vendors • Project focused on systems at 100,000 tpy
Biogas Use Options • Direct use – typically provides best economics, requires user proximity • Electric generation – proven technology, scalable, renewable • Combined heat and power – benefits of both direct use and electricity • Fuel cells – unknown with AD of MSW or SSOM • Pipeline quality – treatment required, expensive
SSOM Supply Assessment • Notable current recovery programs: • Backyard composting • Food waste direct to livestock • Food waste manufactured into animal feed • SSOM composting • Significant amount of SSOM still disposed in the mixed MSW waste stream
Facility Design Considerations • Originally intended to work with experienced system vendors to describe and develop cost estimates • Did not happen • Developed preliminary facility design assumptions and costs via building up components
Facility Design Considerations • Process Flow & Scalability • Mass Balance • Receiving & Preparation • Processing • Site Needs
Facility Design Considerations • Ideal = scalable & redundant (2 lines) • Conveyors, bag breakers, trommels, metal separation, shredder, blending tanks, digesters, gas conditioning, end use, digestate handling • Scalable – # of lines, # of digesters, etc • 21 days in digesters • Biogas yield of 400,000 to 525,000 MMBTUs per year • 165 tons per day of dewatered compost
Site Needs • 8 acres • Digesters require high soil loading support • Utilities – electricity, steam, compressed air, sewer • Site security - typical
Permitting and Environmental Considerations • No current AD facilities operating with MSW as a feedstock • Permit needs anticipated to include: • EAW • EIS • Emissions: air, water, solids • Other Federal, State/MPCA • Local • PUC
Economic Analysis • Capital costs • System vendor response lacking • Published sources • “Plant build up” estimate • O&M costs • Published • Plant build up • Revenues
Economic Analysis • Capital costs – published sources • Adjusting for scope, cost range is $30M to $45M for 100,000 tpy facility • Capital Cost – Plant Build Up • $38,580,000 • O&M Published Sources • Typical $20 to $60 per ton • O&M Plant Build Up • $53/ton for direct use option • $58/ton for electrical generation option
Economic Analysis • Revenues • Electrical generation: >$3M/yr or $30/ton (assuming $0.06/kWh) • Biogas sales: $2.28M to $4.24M/yr or $23 to $42/ton (assuming $6-$8/MMBTU) • Anticipated Tip Fees • Debt Service estimated at $30 per ton • Estimated Net cost per ton $55-$60
Schedule • Siting 3 - 6 mo • Funding 3 - 9 mo • Prelim engineering 3 mo • Permitting 12 -15 mo • Construction 18 - 20 mo • Startup/commissioning 3 - 4 mo • Total 42 – 57 mo