Source Separated Organic Materials Anaerobic Digestion Feasibility Study
Prepared for
Ramsey/Washington Counties Resource Recovery Project Board
And theSt 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 compostingFood waste direct to livestockFood waste manufactured into animal feedSSOM composting
Significant amount of SSOM still disposed in the mixed MSW waste stream
Estimated SSOM and Yard WasteAs Disposed
Material Type Residential(tons)
Commercial(tons)
TOTAL(tons)
Source Separated Organic Material
189,000 200,000 389,000
Yard Waste (+Smaller Wood Waste)
47,000 13,000 60,000
TOTAL 236,000 213,000 449,000
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:EAWEISEmissions: air, water, solidsOther Federal, State/MPCALocalPUC
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 FeesDebt Service estimated at $30 per tonEstimated 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
