How to define and provide evidence of the Performance of Biogas Plants

The administration and performance evaluation of biogas plants in GermanyJan Postel, Dr. Britt Schumacher, Dr. Jan Liebetrau

The 3rd International Cooperation Conference on Biogas Industrialization in China (Organizers: CAAA, DLG, CBS) 19.05.2012 Nanjing, China

DBFZ Deutsches Biomasseforschungszentrum gemeinntzige GmbH, Torgauer Str. 116, D-04347 Leipzig, www.dbfz.de

DBFZ Deutsches Biomasseforschungszentrumgemeinntzige GmbH

Performance evaluation of biogas plantsEfficiency: Ratio of actual power output and power input

What is required to evaluate a biogas plant?Mass balance of in- and outputEnergy balance of the biogas plant, including in- and outputData of the reliability of the equipment (hours/year)

What is needed for the mass/energy balances and the reliability data?Characterization of substrates Main state of the art technologies (data acquisition)Losses/EmissionsEvaluation of the overall biogas plant concept

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Performance evaluation of biogas plants (process chain)Energy cropsDistribution/Application digestateBiogas

Storage tank (digestate)

Excrements

Preliminary tankSubstrate-Feed in

Gas-storage

Digester

SiloSubstrate-storage

Digestate

Biogas-utilization3What is required to evaluate a biogas plant?Mass balance of in- and outputEnergy balance of the biogas plant, including in- and outputData of the reliability of the equipment (hours/year)e.g. combined heat and power plant (CHP)

Requirements for energy balancesas basis for efficiency evaluation Efficiency: Ratio of actual power output and power inputWhat is necessary for a qualified evaluation?Definition of theoretical energy outputEvaluation, documentation, quantification of mass and energy streams,Evaluation of operational hours, (documentation of down times, flaring events, maintenance periods etc. )Calculation of capacity utilizationActual theoretical comparisonIdentification of bottlenecksOptimization

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Mass balance 5

Grass silageCattle ManureDigesterDigestateInorganic matterOrganic matterWaterWater vapourCarbondioxidMethaneDocumentation and quantification of all relevant mass streams

Mass balancesevaluationDoes the quality and amount of input masses realized in practice meet the design assumptions?Is the Biogas production according to the theoretical value? (consider the conversion efficiency within the CHP as important factor if no direct quantification of the biogas mass flow is available!!)If not check:Substrate quality (is the assumed biogas potential correct?) Infeed amount correct?Quantification of degree of degradation by means of a gas potential test of the digestateStability of biological process (acid concentration?)TemperatureInhibition effectsLeackage of biogas within the gas collection system

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Energy balance

A high degree of utilization of waste heat from the CHP is of enormous relevance for the overall efficiency

Energy balance evaluationIs the energy output as expected?

Electrical: If not check: Biogas production as assumed?CHP unit conversion efficiency as assumed?Consumption of devices on site to large?Downtime - what are bottlenecks of the process? Thermal:If not check: Losses due to poor insulation?Are there other options for heat utilization?8

Characterization of substrates

Biomass / Substrates10

Energy cropsBy-products & ResiduesOrganic waste

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Substrate characteristicsGas potential (maximum biogas yield obtainable) measured or calculated (digestion tests, animal nutrition test, elementary analysis)

Degradation rate (reduction of the concentration of organic substance)

Content of micro (trace) and macro elements

Content of potential inhibitory substances as nitrogen, sulphur, antibiotics etc.

Material handling: pumpability, content of disturbing material (e.g. sand, stones)11

Characterization of Substrates - CompositionDry matter content (DM): waterless (anhydrous) share of a mixture after drying at 105 C.Organic dry matter content (oDM): Mixture free of water (anhydrous) and free of inorganic substances generally per drying at 105 C and annealing at 550 CFractions of fat, protein and carbohydrate analyzed by Weender Animal nutrition analysis12

Representative samples of the biomass are essential for meaningful results!

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Methods of substrates characterization13

Animal nutrition analysisDiscontinuous anaerobic digestionContinuous anaerobic digestion

Methods of substrates characterization14EffortInformative valueDigestion testsBatchMedium (approx. 35 days)Medium (general degradability)ContinuousHigh (months)High (degradability under real conditions, inhibition, deficiencies) Tests to calculate the biogas yieldAnimal nutritionMedium (approx. 1 week)Medium (fat, protein, various carbohydrates, ash)Elementary analysisMedium (approx. 1 week)Low (all elements, but carbon as lignin is not degradable)Data from literaturelowDepended on the quality of source

Representative samples of the biomass are essential for meaningful results!

Biogas potentialSubstrateTS, VS%, %TSbiogas potentialm3/t substratebiogas potentialm3/t VScow manure8-11, 75-8220-30200-500pig manure7, 75-8620-35300-700cow manure25, 68-7640-50210-300Chicken manure32, 63-8070-90250-450Corn silage20-35, 85-95170-200450-700Rye silage30-35, 92-98170-220550-680molasses80-90, 85-90290-340360-490Separately collected biowaste40-75,50-7080-120150-600Lipids from grease separator2-70, 75-9311-450700Glycerin (SEEG)47, 704251295

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15http://www.liquid-energy.eu/Biogasproduktion_und_Glyzerin.138.0.html?=&no_cache=1http://www.rrbconference.com/bestanden/downloads/61.pdf

Characterization of Substrates - ConclusionSubstrates differ in energy density, composition and degradabilityMostly pre-treatment enhances the degradability of substrates, except for lignin, which is only aerobic degradable High amounts of extreme easy degradable substrates can lead to process failure, due to a excessive acid productionMono-fermentation can lead to an unbalanced nutrient supply, therefore a suitable mixture of substrates or a supply with lacking nutrients are recommendable High concentrations of ammonia can lead to difficulties in the biological processHigh concentrations of sulphur can cause damage e.g. CHPSand and stones can lead to technical difficulties16

2. main state of the art technologies

General technical requirements18high reliability/durability and short maintenance interruptions of all plant components are essential for high operating and full load hours the overall process has to be reliable!

Technology has to match the substrate/biomass, sufficient flexibility for change in substrate

Capacity of the plant as a whole and the plant components have to match the actual substrate and mass flows

Low energy consumption

Easy to monitor and control

Biomass and reactor type19Digester type is selected according to the substrate characteristics

Agricultural application TS between 3 12 % continuous stirred tank reactor (CSTR), manure and energy crops

plug flow digesters mostly for higher total solid concentrations

Box/garage type digestion only for biomass, which is stackable and can be easily saturated by percolate (landscape management material, separately collected biowaste), highly insensitive to sand, rocks, disturbing material

Continuously stirred tank reactor (CSTR)

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Plug Flow Tank Reactor (PFTR)21

verticalhorizontalIntakeDischarge

Batch Reactor22

Prozeschema Boxenfermenter (Abbildung: BEKON GmbH Co. KG); Fotos: Bekon GmbH (oben), DBFZ (unten)Garage type digester discontinuous

Process evaluationLaboratory testsDegradation of VS, TS, TOC, CODContent of organic acids (sum parameter)Content of organic acids (portion of each acid)

not permanent availableneed of sampling time consuming, difficult to automate, high information content

Online measurementInputGas production ratepH-value Methane contentCarbondioxid contentHydrogen contentTemperature

Permanent available,easy integration to automated processinformation content???

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Technologies - Conclusion

Energy output depended on many factors (substrate qualities, stability of biological process, efficiencies and availabilities technical devices)

Primary target should be: process stability, reliability of technology

Secondary target: gas production rate and energy output

The energy consumption of all devices should be kept by a minimum

A high degree of utilization of waste heat from the CHP is of enormous relevance for the overall efficiency

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Losses/Emissions

Losses / Emissions

Losses reduce the energy output and lead to emissions (gaseous, liquid, solid)

Need to minimize losses toprevent environmental pollution avoid the release of greenhouse gasesprevent the release of toxic substancesensure high energy efficiency ensure economical operation

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Sources of emissions within the process chainEnergy cropsDistribution/Application digestateBiogas

Storage tank (digestate)

Excrements

Preliminary tankSubstrate-Feed in

Gas-storage

Digester

SiloSubstrate-storage

Digestate

Biogas-utilizationElevated N2O undNH3-Emissionsdue to crop growing ?Humus balance?Nutrition balance?Silage losses5-20% ?No data available - preliminary tankmethane losses of the plant? Leakages? Coverage? Relief pressure valve? Emissions not extensively investigated yet dependend on substrates, moisture content of the soil,climate, time and period of application Large variations in N2O emissionse.g. Methane emissions from open storage tanks;Dependend on processing + substratesMethane losses Biogas upgrading?

Emissions- from the Co generation unit ?Emissions influenced by distribution techniques 27

Possible losses I28Silage storage facilities Respiration and decomposition of organic matter

Hopper/ preliminary tank/ open hydolysisHopper used for mixing of substrate with digestateMethane (CH4), Hydrogen (H2)

Solid material feed in deviceRespiration and decomposition of organic matter

Digester Permeability of rubber membrane, leakages and pressure relief valves Mainly Methane (CH4)

Possible losses II29

Storage tank (digestate)Methane (CH4), nutrients (fertilizer value) (NH3,(N2O))

Gas utilizationCo generation unitMainly Methane (CH4) and unburnt hydrocarbon (CnHm)

Upgrading facilities (Feed in with natural gas quality)Methane slip (CH4)

30Gas potential of digestatesSpecific biogas yield (l*kgVS-1)

Time (d)Low retention times lead to incomplete substrate utilizationFor comparison: 18-70 m/t digestate

3. Losses / Emissions - Conclusion

due to environmental and economic reasons losses should be avoided

Plant design, substrate and operation of the plant affect the amount of losses

Frequent check of the plant and operational management should be self-evident

Actual theoretical comparison is needed for precise identification of losses!

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4. Evaluation of the overall biogas plant concept

Evaluation for OptimizationAim: Achieving of a defined target state (optimum) by well-directed modification of current situation

No independent optimization of isolated items possible, due to mutual dependency33Source: Leitfaden Biogas; www.fnr.deProcedureProcess controlAvailabilityCapacity utilizationEfficiencyGreenhouse gas emissionsOdour emissionsNoise emissions

Investment costsOperational costsIncome

4. Evaluation of the overall biogas plant concept - ConclusionAre technology and substrates (texture/amount) a good match? Which ratio of energy production to energy consumption is achievable? (electricity and heat)Fits the plant to operational needs, infrastructure and consumers - gas, electricity and/or heat grid?Are collection and documentation of data appropriate to avoid malfunction?Are the losses reduced to a minimum?Which climatic conditions are to consider? Are insulation or cooling needed?Are the distances between biogas plant and substrates source respectively between biogas plant and residues application short enough? (logistics, costs)Are aspects of environmental protection to consider?34

Research for the Energy of the Future

Deutsches BiomasseForschungsZentrum German Biomass Research CentreTorgauer Strae 116D-04347 Leipzig

www.dbfz.deTel./Fax. +49(0)341 2434 112 / 133Contact: Dr.-Ing. Jan Liebetrau Jan Postel Dr. Britt SchumacherThank you very much for your attention!

Diagramm30.036801733600-0.0427674109000.036828447624.2888641823.744969839217.963475413119.826770139115.48944775060.036990216739.432947092353.531703896128.945744672833.827868624929.15989020620.037056168761.347954636184.044598944748.822137203146.196688879239.96199003290.036859151995.6525921422116.042737499269.5195178559.346094499151.44361404910.0369489779113.8742296877154.218031117875.364972800171.144192530462.29828040020.0367995962143.9413085251200.100794915282.155443612382.1955207971.86528059770.0369720101163.1682013105247.148816308386.283997496489.070114440978.944214640918.1043804415182.5853476528296.016856696691.833562471497.451822190787.081865337620.5753329264196.3882511773327.12412518496.6918561434102.343415020592.576413884323.215476845205.1723860263355.106558033101.472504288111.643246478100.49074833326.4489176758215.0709691751370.1234115651107.4012493327117.8629586111106.042097989429.3986168948224.4831108517382.4353613865113.455585547123.9116529222111.489172776630.4980780353232.3951107458395.1975198263119.2847348533129.7138502844117.113966309628.1397015623236.0095271145407.4528311219124.090289448133.9517708901121.398164670529.588328857244.4535668312420.9170867402130.3061022831138.4576728466126.33961955134.0577135412253.7051234915433.1062917004135.6000843857142.3535864443130.158719996130.6837585966256.9932855981444.5715667966142.0708974294146.9681342931134.970429632130.0062866985261.3016254596456.3654673081148.7524337071152.4399204428140.409356778232.0685199081266.9265640072465.2940040935153.9404894306156.6582864519144.364116844628.8860934328267.0320243098472.7815909262158.523218268160.8695615249148.396642371129.5505988299271.1309707286479.3022849899164.5114915863165.3268441401152.585896288330.5577061123274.8015982962485.7966351982170.4425121079170.4150948254157.299766809729.836728306277.2496855538490.6887138913175.7075551538175.0799917825161.528378244331.1852582621279.8282117886496.322967393181.6672712215180.7414927909166.253379834731.1694702897281.1464123785497.9276809353184.0356328706181.277760158167.878587077531.5483898265282.6324934666502.7941974651190.304367817184.1859613399171.927236063935.6147204683287.9266075342506.6646702319194.8247116821188.8936778943176.102710483938.7391732981292.2207340233510.5797125024199.6703195557193.297085256179.94017380639.2345002576294.6079227072510.6763406867200.6166869748193.5679990744180.65746770137.6639192067294.7620347796512.968290541204.7254771817195.9582530968183.057915971138.7443964908297.2044644005521.364182839214.6422056651204.8957617555191.699379840.3157744028300.2935324009521.5003529231215.7432279647205.834343543192.650006536540.6128052872301.7347436513342.2728690322305.62454156113445.4936469533309.98953638773546.36381038533646.39141404873745.366759028638

AltenoBassumHoppstdtenFrankfurtBblingenKirchstockach

Tabelle1AltenoBassumHoppstdtenFrankfurtBblingenKirchstockach

Tabelle10.036801733600-0.0427674109000.036828447624.2888641823.744969839217.963475413119.826770139115.48944775060.036990216739.432947092353.531703896128.945744672833.827868624929.15989020620.037056168761.347954636184.044598944748.822137203146.196688879239.96199003290.036859151995.6525921422116.042737499269.5195178559.346094499151.44361404910.0369489779113.8742296877154.218031117875.364972800171.144192530462.29828040020.0367995962143.9413085251200.100794915282.155443612382.1955207971.86528059770.0369720101163.1682013105247.148816308386.283997496489.070114440978.944214640918.1043804415182.5853476528296.016856696691.833562471497.451822190787.081865337620.5753329264196.3882511773327.12412518496.6918561434102.343415020592.576413884323.215476845205.1723860263355.106558033101.472504288111.643246478100.49074833326.4489176758215.0709691751370.1234115651107.4012493327117.8629586111106.042097989429.3986168948224.4831108517382.4353613865113.455585547123.9116529222111.489172776630.4980780353232.3951107458395.1975198263119.2847348533129.7138502844117.113966309628.1397015623236.0095271145407.4528311219124.090289448133.9517708901121.398164670529.588328857244.4535668312420.9170867402130.3061022831138.4576728466126.33961955134.0577135412253.7051234915433.1062917004135.6000843857142.3535864443130.158719996130.6837585966256.9932855981444.5715667966142.0708974294146.9681342931134.970429632130.0062866985261.3016254596456.3654673081148.7524337071152.4399204428140.409356778232.0685199081266.9265640072465.2940040935153.9404894306156.6582864519144.364116844628.8860934328267.0320243098472.7815909262158.523218268160.8695615249148.396642371129.5505988299271.1309707286479.3022849899164.5114915863165.3268441401152.585896288330.5577061123274.8015982962485.7966351982170.4425121079170.4150948254157.299766809729.836728306277.2496855538490.6887138913175.7075551538175.0799917825161.528378244331.1852582621279.8282117886496.322967393181.6672712215180.7414927909166.253379834731.1694702897281.1464123785497.9276809353184.0356328706181.277760158167.878587077531.5483898265282.6324934666502.7941974651190.304367817184.1859613399171.927236063935.6147204683287.9266075342506.6646702319194.8247116821188.8936778943176.102710483938.7391732981292.2207340233510.5797125024199.6703195557193.297085256179.94017380639.2345002576294.6079227072510.6763406867200.6166869748193.5679990744180.65746770137.6639192067294.7620347796512.968290541204.7254771817195.9582530968183.057915971138.7443964908297.2044644005521.364182839214.6422056651204.8957617555191.699379840.3157744028300.2935324009521.5003529231215.7432279647205.834343543192.650006536540.6128052872301.7347436513342.2728690322305.62454156113445.4936469533309.98953638773546.36381038533646.39141404873745.366759028638

AltenoBassumHoppstdtenFrankfurtBblingenKirchstockach

Tabelle2

Tabelle3