TECHNOLOGY REVIEW OF HIGH SOLIDS DIGESTION OFSSO AND

FEASIBILITY STUDY OF ANAEROBIC DIGESTIONJANUARY 2010

PRESENTED TO NEW YORKPRESENTED TO NEW YORKSWANA TECHNICAL TRAININGSWANA TECHNICAL TRAINING

SEMINARSEMINARJUNE 20, 2012JUNE 20, 2012

Bob SpencerBob SpencerENVIRONMENTAL PLANNINGENVIRONMENTAL PLANNING

CONSULTANTCONSULTANTVERNON, VTVERNON, VT

FEASIBILITY STUDY OF ANAEROBICDIGESTION USING

DRY FERMENTATION TECHNOLOGY

MASS NATURAL COMPOSTINGMASS NATURAL COMPOSTINGFACILITYFACILITY

MASS NATURALMASS NATURAL’’S OPERATIONS OPERATION

Composting pads and a detention basin for runoffcontrol

Composting is accomplished by static pile and turnedwindrows

Mass Natural recently purchased two in-vesselcomposting systems that have expanded the range ofmaterials composted

MN also has a vermicomposting operation to producevermicompost, as well as red wiggler worms whichare offered for sale through the MDEP web site

MATERIALS COMPOSTED SINCEMATERIALS COMPOSTED SINCE1987: 24 YEARS OF OPERATION1987: 24 YEARS OF OPERATION

Paper mill sludge, or short paper fiberPaper mill sludge, or short paper fiber Chicken and horse manureChicken and horse manure Industrial food waste from processors of cranberries,Industrial food waste from processors of cranberries,

juices, soy, fish, bakeries, FOGjuices, soy, fish, bakeries, FOG Yard wasteYard waste Animal mortalities from former chicken egg farm atAnimal mortalities from former chicken egg farm at

Mass Natural and as emergency disposal site forMass Natural and as emergency disposal site forMDEPMDEP

Numerous trials with commercial food waste fromNumerous trials with commercial food waste fromrestaurants and supermarketsrestaurants and supermarkets

Started accepting SSO from supermarkets/restaurantsStarted accepting SSO from supermarkets/restaurantsin June 2011in June 2011

EXISTING PERMITS AT MASSEXISTING PERMITS AT MASSNATURALNATURAL

Solid Waste Facility Site Assignment from theSolid Waste Facility Site Assignment from theTown of Westminster Board of HealthTown of Westminster Board of Health

Solid waste composting permits from theSolid waste composting permits from theMassachusetts Department of EnvironmentalMassachusetts Department of EnvironmentalProtectionProtection

Agricultural composting registration from theAgricultural composting registration from theMassachusetts Department of AgriculturalMassachusetts Department of AgriculturalResources.Resources.

MASS NATURAL COMPOSTMASS NATURAL COMPOSTPRODUCTSPRODUCTS

““Top ShelfTop Shelf”” organic loam, a blend of compost, sand,organic loam, a blend of compost, sand,loam is distributed by a number of garden centersloam is distributed by a number of garden centers

Compost is distributed by a number of garden centersCompost is distributed by a number of garden centers Vermicompost and red worms for MDEP and gardenVermicompost and red worms for MDEP and garden

centerscenters Products have been used by the landscaping industryProducts have been used by the landscaping industry

for new lawns, organic lawn care, and athletic fieldsfor new lawns, organic lawn care, and athletic fields Wetland replication projectsWetland replication projects Landfill cap vegetative coverLandfill cap vegetative cover

SITE ADVANTAGESSITE ADVANTAGES

Existing permits to compost organics;Existing permits to compost organics; UnderUnder--utilized, existing buildings within permitted areautilized, existing buildings within permitted area Local electrical distribution line is capable of receivingLocal electrical distribution line is capable of receiving

considerable current from an onconsiderable current from an on--site engine generator;site engine generator; Existing equipment (frontExisting equipment (front--end loaders, rotary drum aerobicend loaders, rotary drum aerobic

compost vessel, agitated bay compost system, deck screens,compost vessel, agitated bay compost system, deck screens,trucks, etc.) and personnel to handle large volumes of organictrucks, etc.) and personnel to handle large volumes of organicmaterial;material;

Many years of experience with, and understanding of, the localMany years of experience with, and understanding of, the localorganics market;organics market;

Compost the dry fraction of the digested effluent to add valueCompost the dry fraction of the digested effluent to add valueto its current product;to its current product;

EXISTING STRUCTURESEXISTING STRUCTURES

6 former chicken houses with concrete pads 65 feet6 former chicken houses with concrete pads 65 feetwide by 450 feet long, which may be suitable as awide by 450 feet long, which may be suitable as afloor for some portion of a new AD facilityfloor for some portion of a new AD facility

A 9,000 sf former egg processing/packaging/storageA 9,000 sf former egg processing/packaging/storagefacilityfacility

Electrical building with 3Electrical building with 3--phase powerphase power Existing padmount distribution transformer that isExisting padmount distribution transformer that is

rated 1,000 kVA, sufficient to export the entire 848rated 1,000 kVA, sufficient to export the entire 848kW output from the proposed anaerobic digesterkW output from the proposed anaerobic digester

Water supply wellsWater supply wells OfficeOffice

WET VS DRY TECHNOLOGYWET VS DRY TECHNOLOGYOROR

LOW SOLIDS VS HIGH SOLIDSLOW SOLIDS VS HIGH SOLIDS Project started by looking at both wet and dryProject started by looking at both wet and dry

fermentation systemsfermentation systems Decision to not pursue wet fermentation due to theDecision to not pursue wet fermentation due to the

fact that there is no sewer connection available atfact that there is no sewer connection available atMass Natural to handle the significant amount ofMass Natural to handle the significant amount ofliquid wastewater that would be generated by a wetliquid wastewater that would be generated by a wetfermentation systemfermentation system

Although the liquid wastewater can potentially beAlthough the liquid wastewater can potentially beland applied, that scenario would have requiredland applied, that scenario would have requiredconstruction of very large holding tanks, and thenconstruction of very large holding tanks, and thencontracting for land application, something Masscontracting for land application, something MassNatural is not prepared to do at this point in time.Natural is not prepared to do at this point in time.

FEEDSTOCKS FOR HIGHFEEDSTOCKS FOR HIGHSOLIDS ANAEROBICSOLIDS ANAEROBIC

DIGESTIONDIGESTION Approximately 52 tons/day Solids Content 62% Volatile Solids 88% of Total Solids Ammonia/Ammonium Concentration: 3,777Mg/l Biogas Generation: 480 m3/hour Methane Content 62% Electrical Output Potential 1,109kW Based on engine-genset electrical efficiency of 36.3%

Electricity GenerationElectricity Generation At full output, the Jenbacher JS3 316 engine gensetAt full output, the Jenbacher JS3 316 engine genset

has a heat rate of approximately 9,400 Btu/kWh,has a heat rate of approximately 9,400 Btu/kWh,which translates to an electrical efficiency of 36.3%.which translates to an electrical efficiency of 36.3%.

Given typical operations and maintenance schedules,Given typical operations and maintenance schedules,one can expect an engine genset to operate at fullone can expect an engine genset to operate at fullcapacity a maximum of 90% of the hours in a yearcapacity a maximum of 90% of the hours in a year

A dry digestion system will typically use about 7.5%A dry digestion system will typically use about 7.5%of the rated electrical output to run the pumps andof the rated electrical output to run the pumps andcontrols of the plantcontrols of the plant

Mass Natural can expect to export a maximum ofMass Natural can expect to export a maximum of6,128,496 kWh/yr.6,128,496 kWh/yr.

Thermal EnergyThermal Energy Mass Natural can benefit from the thermal energy released from tMass Natural can benefit from the thermal energy released from the waste heathe waste heat

from the enginefrom the engine The combined heat that can be captured from the engine jacket isThe combined heat that can be captured from the engine jacket is about 1.95about 1.95

MMBtu/hrMMBtu/hr The amount of heat that can be captured from the exhaust stack iThe amount of heat that can be captured from the exhaust stack is about 1.9s about 1.9

MMBtu/hrMMBtu/hr A potential use of the heat is to dry incoming feedstocksA potential use of the heat is to dry incoming feedstocks A rotary drum dryer that would be appropriate at Mass Natural woA rotary drum dryer that would be appropriate at Mass Natural would have auld have a

thermal efficacy of about 60%thermal efficacy of about 60% For each 4 MMBtu/hr of heat available, a dryer can evaporate appFor each 4 MMBtu/hr of heat available, a dryer can evaporate approximately 2,500roximately 2,500

pounds of water or 300 gallonspounds of water or 300 gallons Therefore, in a typical 8Therefore, in a typical 8--hour shift, MNF could dry 5 tons of material that has ahour shift, MNF could dry 5 tons of material that has a

solids content of 35% into 4 tons of material that has a solidssolids content of 35% into 4 tons of material that has a solids content of 45%content of 45% Mass Natural could utilize the 3.85 MMBtu/hr available from theMass Natural could utilize the 3.85 MMBtu/hr available from the waste heat of thewaste heat of the

engineengine Another option would be to uses the thermal heat for a greenhousAnother option would be to uses the thermal heat for a greenhousee

HIGH SOLIDS BATCH PROCESSINGHIGH SOLIDS BATCH PROCESSING

In a batch process, the digester is completely filledIn a batch process, the digester is completely filledwith organic matter and closed with a gaswith organic matter and closed with a gas-- and liquidand liquid--tight sealtight seal

The digester remains closed until the end of theThe digester remains closed until the end of thedesired retention time, typically 14 to 28 daysdesired retention time, typically 14 to 28 days

It is then emptied and filled with new material, oftenIt is then emptied and filled with new material, oftena mixture of partially digested material that was justa mixture of partially digested material that was justremoved and fresh, undigested materialremoved and fresh, undigested material

The partially digested material acts a seed material toThe partially digested material acts a seed material torere--start the digestion process.start the digestion process.

LOADING A DRYLOADING A DRY--BATCHBATCHDIGESTER CELLDIGESTER CELL

GENERATOR AT BEKON FACILITYGENERATOR AT BEKON FACILITY

ADVANTAGES OF HIGH SOLIDSADVANTAGES OF HIGH SOLIDSAD TECHNOLOGYAD TECHNOLOGY

Because dry material is stackable, the digester can be loaded wiBecause dry material is stackable, the digester can be loaded with ath afrontfront--end loader, which is already at a compost facilityend loader, which is already at a compost facility

When the material is finished digesting, it still has a relativeWhen the material is finished digesting, it still has a relatively highly highsolids content. Therefore, the effluent can be composted withousolids content. Therefore, the effluent can be composted without havingt havingto remove much liquid from itto remove much liquid from it

Pumping liquid percolate is much easier than pumping slurries, wPumping liquid percolate is much easier than pumping slurries, which ishich isthe case in most commercial digestion systems. Pumping slurry rthe case in most commercial digestion systems. Pumping slurry requiresequiressignificant horsepower, and the pipes are prone to cloggingsignificant horsepower, and the pipes are prone to clogging

To reduce the impact of reduced biogas production that occurs whTo reduce the impact of reduced biogas production that occurs when theen thedigester is redigester is re--filled, multiple digesterfilled, multiple digester ““cellscells”” can be employed so thatcan be employed so thatseveral are operating at capacity at any one timeseveral are operating at capacity at any one time

If one digester cell has an upset condition, the percolate fromIf one digester cell has an upset condition, the percolate from it is dilutedit is dilutedby the percolate from the other cells, making it easier to reby the percolate from the other cells, making it easier to re--start astart a““stuckstuck”” cell. In an extreme case, the percolate can be completelycell. In an extreme case, the percolate can be completelyisolated and removed from circulationisolated and removed from circulation

DryDry--Batch Digester Installations inBatch Digester Installations inEuropeEurope

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BEKON AND BIOFERMBEKON AND BIOFERM

Mass Natural solicited proposals from twoMass Natural solicited proposals from twoGerman companies, Bekon and Bioferm, thatGerman companies, Bekon and Bioferm, thatappear to be market leadersappear to be market leaders

Each has more than a dozen operatingEach has more than a dozen operatingdigesters in Europe and is constructing moredigesters in Europe and is constructing moreeach montheach month

Both technologies share a similar processBoth technologies share a similar process

SIMILAR PROCESSSIMILAR PROCESS Digestible, organic matter is loaded into a long, narrow gasDigestible, organic matter is loaded into a long, narrow gas--tight buildingtight building Once the building is sealed, it is saturated with percolate thatOnce the building is sealed, it is saturated with percolate that containscontains

anaerobic microanaerobic micro--organisms from an active digesterorganisms from an active digester Percolate is periodically drained and rePercolate is periodically drained and re--sprayed into the digester over asprayed into the digester over a

period of approximately 28 daysperiod of approximately 28 days Biogas is collected and a combusted in an engineBiogas is collected and a combusted in an engine--genset to producegenset to produce

electricityelectricity Waste heat from the engine is used to maintain an ideal temperatWaste heat from the engine is used to maintain an ideal temperature withinure within

the digestersthe digesters After the prescribed retention time, the digester is opened, theAfter the prescribed retention time, the digester is opened, the organicorganic

matter is removed, and some of it (a third to half of it) is mixmatter is removed, and some of it (a third to half of it) is mixed with freshed with freshorganic material and loaded back inside the digesterorganic material and loaded back inside the digester

The digested material is actively composted.The digested material is actively composted.

BEKON AD TECHNOLOGYBEKON AD TECHNOLOGY

BEKON FACILITYBEKON FACILITY

COMPUTER MONITORING OFCOMPUTER MONITORING OFEACH DIGESTER BATCHEACH DIGESTER BATCH

BIOFERM FACILITYBIOFERM FACILITY

SUMMARY OF FEASIBILITY STUDYSUMMARY OF FEASIBILITY STUDY

High solids anaerobic process was best suited for the site.High solids anaerobic process was best suited for the site. Mass Natural could digest approximately 52 ton per day ofMass Natural could digest approximately 52 ton per day of

mixed organic mattermixed organic matter Sufficient biogas to power an 848Sufficient biogas to power an 848--kW engine genset thatkW engine genset that

would export over 6.1 MWh a year of renewable electricitywould export over 6.1 MWh a year of renewable electricity The system would cost $5.5M to $8.4MThe system would cost $5.5M to $8.4M Annual operating budget of about $277,000Annual operating budget of about $277,000 Ancillary benefits would include over 3.8 MMBtu/hr ofAncillary benefits would include over 3.8 MMBtu/hr of

thermal energy for onthermal energy for on--site usesite use Over 3,250 greenhouse gas emissions credits for sale.Over 3,250 greenhouse gas emissions credits for sale.

OPERATING COSTSOPERATING COSTS

Operating costs for the anaerobic digestersystem were estimated by the Brendle report tobe approximately $130,000 per year assuming1.5 full-time equivalent employees

Operating costs for the CHP operation areestimated at $137,000 per year

Total operating cost of $277,000 per year

MASS NATURAL PROJECTMASS NATURAL PROJECTREVENUE AND FINANCING FORREVENUE AND FINANCING FOR

$8.4 MILLION FACILITY$8.4 MILLION FACILITY Project revenue is estimated at approximately $1.9 million in

the first year of full operation. That revenue is based on anaverage tipping fee of $45/ton of feedstock, and receipt of$0.10/kwh of electricity generated.

Assumptions for project financing were based on 35.5% oftotal costs financed with solid waste bonds, 23% byinvestment tax credit, and the balance by equity investment.With this combination of revenue and financing the estimatedreturn on investment, EBITDA (earnings before interest, taxes,depreciation and amortization), divided by pre-debt capitalcosts, is 13.4%

This yields a payback period of 7.5 years

STUDY CONCLUSIONSSTUDY CONCLUSIONS

• Based on laboratory testing of many of these foodwastes, it was determined that 20,000 tons per year offood wastes would generate sufficient quantities ofbiogas to power a 848 kW generator.

• Two technology vendors with numerous, successfullyoperating high solids anaerobic digestion technologiescurrently operating in Germany have technology that istechnically feasible for implementation at Mass Natural.

• Sufficient types and quantities of industrial food wasteare available within economical hauling distances ofMass Natural’s Westminster, Massachusetts compostingfacility to supply a 20,000 ton per year high solidsanaerobic digestion facility.

• The electrical interconnection from a generator poweredby an anaerobic digester is feasible and economical atMass Natural.

STUDY CONCLUSIONSSTUDY CONCLUSIONS• The Mass Natural site has sufficient space to locate an anaerobic

digestion facility• The current composting operation at Mass Natural would be a

complimentary operation for an anaerobic digestion facility• The regulatory approval process for an anaerobic digestion facility

at Mass Natural was determined to be feasible.• The capital costs for an anaerobic digestion facility at Mass Natural

was determined to be between $5.5 and $8.4 million. For a 20,000ton per year facility this was determined by Mass Natural to be amarginal investment.

• Mass Natural would like to conduct further evaluation to identifyless costly high solids dry fermentation technologies.

PROJECT COMPONENTSPROJECT COMPONENTS

HARVEST POWER FACILITYHARVEST POWER FACILITY

GICON FACILITYGICON FACILITYGERMANYGERMANY

METHANIZATION TANKS &METHANIZATION TANKS &GAS STORAGEGAS STORAGE

BAL FACILITYBAL FACILITYGERMANYGERMANY

OSH KOSH, WISCONSINOSH KOSH, WISCONSINBIOFERMBIOFERM

OSH KOSH PLANTOSH KOSH PLANTSTARTS OPERATION 2011STARTS OPERATION 2011

LESSONS LEARNEDLESSONS LEARNED

NEED SOURCES OF SSONEED SOURCES OF SSO NEED LONGNEED LONG--TERM CONTRACTS FORTERM CONTRACTS FOR

SSOSSO NEED RFPSNEED RFPS NEED CONTRACTS FOR SSONEED CONTRACTS FOR SSO NEED WASTE ORGANIC WASTE BANSNEED WASTE ORGANIC WASTE BANS CT, VT, MA BANSCT, VT, MA BANS NEED REGULATIONSNEED REGULATIONS

LESSONS LEARNEDLESSONS LEARNED

NEED FEEDNEED FEED--ININ--TARRIF OF $0.12/KWHTARRIF OF $0.12/KWH MODEL FACILITIESMODEL FACILITIES R&DR&D CORPORATE/INSTITUTIONALCORPORATE/INSTITUTIONAL

SUSTAINABILITYSUSTAINABILITY INFORMATION EXCHANGEINFORMATION EXCHANGE LESS PROPRIETARY PARANOIALESS PROPRIETARY PARANOIA