Anaerobic Digestion - eXtension English System standard measure of heat energy. ... , a heat recovery system ... An enclosed tank in which anaerobic digestion of organic wastes takes place. Digestate

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  • Anaerobic bacteria Microorganisms that live and reproduce in an environment containing no free or dissolved oxygen.

    Anaerobic digester Avesselandassociatedheatingandgascollectionsystemsdesignedspecificallytocontainbiomass

    undergoingdigestionanditsassociatedmicrobiallyproducedbiogas.Conditionsprovidedbythedigesterinclude:anoxygen-freeenvironment,aconstanttemperature,andsufficientbiomassretentiontime.

    Anaerobic digestion Abiologicalprocessinwhichmicrobesbreakdownorganicmaterialinanoxygen-freeenvironmentwhile

    producingbiogasasaby-product.

    Anaerobic lagoon Aholdingpondforlivestockmanurethatisdesignedtoanaerobicallystabilizemanure,andmaybedesignedto

    capturebiogaswiththeuseofanimpermeable,floatingcover.

    Annual capital cost The equivalent annual capital cost converts the total capital costs into an annual charge. The equivalent annual

    capital cost is calculated according to the formula EAC=pv/(1/r-1/(r*(1+r)^n))wherepvisthepresentvalueortotalcapitalinvestmentintodaysdollars,risthe

    discount rate, and n is the life of the capital investment.

    Biogas Forthepurposesofthisdocument,therawandun-cleanedgasproducedbyadigester,consistingofmainly

    methane(~60%),carbondioxide(~40%),watervapor,andhydrogensulfide.

    Biological Oxygen Demand (BOD) Theamountofoxygenrequiredbyaerobicmicroorganismstodecomposetheorganicmatterinasampleof

    water,suchasthatpollutedbysewage.Itisusedasameasureofthedegreeofwaterpollution.

    British Thermal Unit (Btu) TheEnglishSystemstandardmeasureofheatenergy.IttakesoneBtutoraisethetemperatureofonepound

    ofwaterbyonedegreeFahrenheitatsealevel.

    Capital cost Aone-timefixedcostincurredonthepurchaseofbuildingsandequipment.Adigesterscapitalcostincludes

    the purchase of land the system is on, permitting and legal costs, the equipment needed to run the digester, costofdigesterconstruction,thecostoffinancing,andthecostofcommissioningthedigesterpriortosteady-state operation of the digester.

    Carbon dioxide (CO2) Acolorless,odorless,non-flammablegasfoundinbiogas.

    ANDIGDecember, 2012

    Anaerobic Digestion Glossary of Terms

  • Carbon to Nitrogen Ratio (C/N) Therelationshipbetweencarbonandnitrogenthatfacilitatesbiogasproduction.AC/Nratioof30permits

    digestiontoproceedatanoptimumrate,assumingotherconditionsarefavorable.

    Centralized digester Ananaerobicvesselwhichusesfeedstocksfromseveralfarmsand/orotherbiomasssources,withinarelatively

    proximate distance to the digester location.

    Co-generation Thesequentialuseofenergyfortheproductionofelectricalandusefulthermalenergy.Thesequencecanbe

    thermalusefollowedbypowerproductionorthereverse,subjecttothefollowingstandards:(a)Atleast5%oftheco-generationprojectstotalannualenergyoutputshallbeintheformofusefulthermalenergy.(b)Whereusefulthermalenergyfollowspowerproduction,theusefulannualpoweroutputplusone-halftheusefulannualthermalenergyoutputequalsnotlessthan42.5%ofanynaturalgasandoilenergyinput.

    Combined Heat and Power (CHP) Thesequentialorsimultaneousgenerationoftwodifferentformsofusefulenergymechanicalandthermal

    fromasingleprimaryenergysourceinasingle,integratedsystem.CHPsystemsusuallyconsistofaprimemover,agenerator,aheatrecoverysystem,andelectricalinterconnectionsconfiguredintoanintegratedwhole.

    Complete mix digester Ananaerobicvesselthatismixedwithoneormoremixingtechniques.

    Covered lagoon digester Thissystemcapturesbiogasunderanimpermeablecover,whiletakingadvantageofthelowmaintenance

    requirementofalagoon.Twolagooncellsareneededforthesystemtooperateefficiently.

    Dewater Todrainorremovewaterfromanenclosure.Dewateralsomeansdrainingorremovingwaterfromsludgeto

    increase the solids concentration.

    Digester Anenclosedtankinwhichanaerobicdigestionoforganicwastestakesplace.

    Digestate Effluent;Materialremainingaftertheanaerobicdigestionofabiodegradablefeedstock.Digestateisproduced

    bothbyacidogenesisandmethanogenesis,andeachhasdifferentcharacteristics.

    Discount rate Theinterestrateusedindiscountingfuturecashflows.

    Distributed generation Adistributedgenerationsysteminvolvessmallamountsofgenerationlocatedonautilitysdistributionsystem

    forthepurposeofmeetinglocal(substationlevel)peakloads.

    Distribution system (electric utility) Thesubstations,transformersandlinesthatconveyelectricityfromhigh-powertransmissionlinesto

    consumers.

  • Effluent Digestate;MaterialexitingtheADvessel.

    Emission Thereleaseordischargeofasubstanceintotheenvironment;generallyreferstothereleaseofgasesor

    particulates into the air.

    End-use sectors The residential, commercial, transportation and industrial sectors of the economy.

    Engine-Generator set Thecombinationofaninternalcombustionengineandageneratortoproduceelectricity;maybesingleordual

    fueled depending on the location and set up.

    Feedstock Anyorganicmaterialwithbiogasproductionpotential.

    Filtrate Liquid component of the digestate after separation.

    Fiber Solid component of the digestate after separation.

    Fixed film digester Acolumnpackedwithmedia,suchaswoodchipsorsmallplasticrings,whichfacilitatesmicrobialcolonization

    enablingthedigestertohaveasmallerfootprintandreducingHRT.

    Flare Adeviceusedtosafelycombustsurplusorunusedbiogas.

    Greenhouse Gas (GHG) Agas,suchascarbondioxideormethane,whichcontributestoawarmingactionintheatmosphere.

    Grid Theelectricutilitycompaniestransmissionanddistributionsystemthatlinkspowerplantstocustomers

    throughhighpowertransmissionlineservice;highvoltageprimaryserviceforindustrialapplications;mediumvoltageprimaryserviceforcommercialandindustrialapplications;andsecondaryserviceforcommercialandresidentialcustomers.Gridcanalsorefertothelayoutofgasdistributionsystemofacityortown.

    High solids digestion Alsoknownasdryfermentation,highsolidsdigestionisusedtotreatstackablematerialssuchasfood

    scraps,yarddebris,andmunicipalsolidswastes.Asthenameimplies,highsolidsdigestersworkwithmaterialsthathaveasolidscontentof25-50%.

    High strength waste Feedstocks,suchasfats,oils,andgreasesorotherorganiccomponents,thathaveahighBiologicalOxygen

    Demand.Thesefeedstocksgeneratealotofbiogasbutcanalsomakeadigestergosourifnotmanagedcorrectly.

  • Hydraulic retention time (HRT) The length of time material remains in the digester.

    Hydrogen sulfide (H2S) Atoxic,colorlessgasthathasanoffensiveodorofrotteneggs.Hydrogensulfidehasseriousnegative

    implicationsforthewearofgashandlingequipmentforananaerobicdigestersystem.

    Hydrolysis Abiologicaldecompositionprocessinvolvedintheanaerobicdigestionoforganicmaterial.

    Influent Biomassonthein-flowsideofatreatment,storage,ortransferdevice.

    Installed capacity Thetotalcapacityofelectricalgenerationdevicesinapowerstationorsystem.

    Kilowatt-hour (kWh) Themostcommonlyusedunitofmeasureoftheamountofelectricpowerconsumedovertime.Thestand-

    aloneunitindicatesonekilowattofelectricitysuppliedforonehour.

    Loading rate Meteringfeedstocksintoadigesterataregular,calculatedrateovertime.

    Lagoon Inwastewatertreatmentorlivestockfacilities,ashallowpondusedtostorewastewaterwherebiological

    activitydecomposesthewaste.

    Manure Thecombinationofurineandfeces.

    Mesophilic Of,relatingto,orbeingatamoderatetemperature(35-40C).

    Methane (CH4) Aflammable,explosive,colorless,odorless,gas.Methaneisthemajorconstituentofnaturalgas,andalso

    usuallymakesupthelargestconcentrationofbiogasproducedinananaerobicdigester.

    Methanogens Activeinphase3ofthedigestionprocess,acids(mainlyaceticandpropionicacids)producedinphase2are

    convertedintobiogasbymethane-formingbacteria.

    Microturbine Asmallcombustionturbinewithapoweroutputrangingfrom25-to500-kW.Microturbinesarecomposedofa

    compressor,combustor,turbine,alternator,recuperator,andgenerator.

    Net generation Grossgenerationminustheenergyconsumedatthegenerationsiteforuseinmaintainingenergyneeds(heat

    orelectric).

  • Net Present Value (NPV) Thepresentvalueofaninvestmentsfuturenetcashflowminustheinitialinvestment.Generally,iftheNPVof

    aninvestmentispositive,theinvestmentshouldbemade.

    Operation and Maintenance (O&M) costs Operatingexpensesareassociatedwithrunningafacility.Maintenanceexpensesaretheportionofexpenses

    consistingoflabor,materials,andotherdirectandindirectexpensesincurredforpreservingtheoperatingefficiencyorphysicalconditionofafacility.

    Plug-flow digester Adesignforananaerobicdigesterinwhichthematerialentersatoneendandistheoreticallypushedinplugs

    towardstheotherend,wherethematerialexitsthedigesterafterbeingdigestedoverthe design HRT.Present value The current value of one or more future cash payments, discounted at some appropriate interest rate.

    Rate of return The annual return on an investment, expressed as a percentage of the total amount invested.

    Siloxane Anyofaclassoforganicorinorganicchemicalcompoundsofsilicon,oxygen,andusuallycarbonand

    hydrogen,basedonthestructuralunitR2SiOwhereRisanalkylgroup,usuallymethyl.

    Slug Alargeinjectionoffeedstockintoadigester.

    Slurry Thecontentsofadigesterundergoinganaerobicdigestion.Whenremovedfromthedigester,slurryisknownas

    digestate.Digestatecaneitherbelandappliedasacropnutrientsource,orfurtherprocessedandseparatedintofiltrateandfiber.

    Sour digester condition Adigestergoessourwhenfermentingbacteriaareproducingmoreorganicacidsthanmethanogenscan

    convertintomethane,causingthepHoftheslurrytodrop.WhenthepHdropsbelow6.8,methanogensdieoffand methane production ceases.

    Stabilization Occurswhenthevolatilesolidscontentofafeedstockisbiologicallyreducedviadetentiontimes,mixingand

    interactionwithfermentingbacteria.

    Thermophilic Of,orrelatingto,orbeingatarelativelyhightemperature(50-60C).

    Thermal sink Astructurethatabsorbsheat.

    Tipping fees Moniesthatarepaidtoasitethatisacceptingoutsidesourcesoforganicmaterial(non-farmbiomass).

  • USDA/NIFA National Facilitation Project The Role of a 21st Century Engaged University

    Thispublicationisavailableonlineat:http://blogs.extension.org/andig1/files/2013/01/ANDIG-Glossary.pdf

    On-linetrainingprogramsonbioenergyandsustainability,on-farmenergyconservationandefficiency,andanaerobicdigestionareavailableonlineat:http://fyi.uwex.edu/biotrainingcenter

    Treatment volume Insidevolumeofananaerobicdigesterthat,undernormaloperatingconditionswouldbefullofmaterial

    undergoinganaerobicdecomposition.

    Turbine Adeviceforconvertingtheflowofafluid(air,steam,water,orhotgases)intomechanicalmotion.

    Volatile solids Thosesolidsinwaterorotherliquidsthatarelostonignitionofthedrysolidsat550degreesCentigrade.

    Glossary definitions come from the following sources:

    Gooch,C.AandJ.L.Pronto.2009.CapitalizingonEnergyOpportunitiesonNewYorkDairyFarms.ParticipantBriefingPaper:ReferenceDocument.PreparedbyCurtA.GoochP.E.andJenniferL.ProntoforDairyPowerNewYorkSummit:CreatingaGreener,CleanerFuture,October29-30,2009.Availableat:

    http://www.usdairy.com/Public%20Communication%20Tools/Sustainability%20GHG%20Projects/Dairy%20Power/Dairy%20Power%20New%20York%20Summit%20Participant%20Brief%20-%20Reference%20Docu-ment%20-%20FINAL%2010%2020%2009.pdfverified12/2012

    LezbergS.,M.C.GouldandM.Jungswirth(eds.).2013.IntroductiontoAnaerobicDigestionCourse.On-line Curriculum.BioenergyTrainingCenter.Availableat:http://fyi.uwex.edu/biotrainingcenterverified12/2012

    Sourcesofadditionalenergytermsusedintheanaerobicdigestionindustrycanbefoundat: PublicInterestEnergyResearch.2006.Glossaryofenergyterms.Availableat: www.pierminigrid.org/glossary.htmlverified12/2012 Kramer,J.2009.WisconsinAgriculturalBiogasCasebook.PreparedforFocusonEnergy.Availableat: http://www.focusonenergy.com/files/Document_Management_System/Renewables/biogas09_casestudy.pdf verified12/2012

    http://blogs.extension.org/andig1/files/2013/01/ANDIG-Glossary.pdfhttp://fyi.uwex.edu/biotrainingcenterhttp://www.usdairy.com/Public%20Communication%20Tools/Sustainability%20GHG%20Projects/Dairy%20Power/Dairy%20Power%20New%20York%20Summit%20Participant%20Brief%20-%20Opportunity%20Analysis%20-%20FINAL%2010%2020%2009.pdfhttp://www.usdairy.com/Public%20Communication%20Tools/Sustainability%20GHG%20Projects/Dairy%20Power/Dairy%20Power%20New%20York%20Summit%20Participant%20Brief%20-%20Opportunity%20Analysis%20-%20FINAL%2010%2020%2009.pdfhttp://www.usdairy.com/Public%20Communication%20Tools/Sustainability%20GHG%20Projects/Dairy%20Power/Dairy%20Power%20New%20York%20Summit%20Participant%20Brief%20-%20Opportunity%20Analysis%20-%20FINAL%2010%2020%2009.pdfhttp://fyi.uwex.edu/biotrainingcenterwww.pierminigrid.org/glossary.htmlhttp://www.focusonenergy.com/files/Document_Management_System/Renewables/biogas09_casestudy.pdf