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