Calculating Bioenergy Technical PotentialBiomass and Biogas Conversion TechnologiesHari YuwonoPromotion of Least-Cost Renewables in Indonesia (LCORE-INDO)Jakarta, 31 August 2018One Day Training “Planning for Bioenergy Development: Calculation of Technical Potential and Financial Aspects”

2OUTLINE• Biomass Technologies:

oDirect CombustionoGasification• Biogas Technologies: Anaerobic digestion

Biomass TechnologiesPlanning for Bioenergy Development: Potential, Technical and FinancialJakarta, 31 August 2018

Electricity from Biomass:Some Transformation Paths Source: wisions.net 4

Biomass Technology Status (1)Source: IEA Bioenergy 2009 5

Biomass Technology Status (2)Source: IEA Bioenergy 2009 6

LHV = Low Heating ValueMCw = Moisture ContentACd = Ash Content Consider density of fuel for transportation challenge, for example:• Rice husk density =122 kg/m3• Paddy grain density = 1400 kg/m3• Rice husk pellets up to 680 kg/m3Biomass Fuel Characteristics

7Source: World Bank Technical Paper N0. 422

•Bales/Pellets of biomass to provide an efficient transportation frombiomass sources to power plant site. Pellets take up a small storage area,and can be easily combusted in an automated process making the use ofthem even more efficient.•Pellets are made in an extruding die press. The feedstock is usually purewood biomass. Sometimes a small amount natural binder can be added tofacilitate the process.Bales Wood PelletsBiomass Densification8

Solid Wastes from Agro IndustriesBagasse Nut shells 9Empty Fruit Bunches from palm oil millRice husk from rice mill

Direct Combustion GasificationFuel flexibility High ModerateTechnology Status Mature Early CommercialTypical Size > 5 MWe except for cogeneration > 1 MWe < 1MWeReliability High Poor to reasonableComplexity High ModerateOperational aspect Relatively easy DifficultFurther information: iea.org and etsap.org, and World Bank Technical Paper no. 422,March 1999 BiomassTechnology Comparison

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Direct Combustion TechnologyPlanning for Bioenergy Development: Potential, Technical and FinancialJakarta, 31 August 2018

Fuel Steam ElectricityDirect Combustion : Steam BoilerEfficiency small (5 – 15 MWe) scale 15 to 20 %Efficiency Large (> 50 MWe) scale > 27 % AshSource: adapted from Takuma 12Generating electricity by burning biomass and producing steam to turn turbine and generator

BiomassstorageBiomassdistribution Cooling towerGeneratorDemin water unit ElectricityMake-up waterMake-up waterBiomassCondensate purgeSteam turbineBoiler CondenserPumpsSource: Adapted from Wikipedia 13Direct Combustion : Steam Boiler

Thermal Efficiency of Steam Boilerhttp://cusustainableenergy.pbworks.com High Thermal Efficiency requires:Input 3 : Temperature and Pressure highOuput 4: Temperature and Pressure lowLimiting factors:• Temperature of combustion• Materials• Investment 14

Mass and Energy Balance for Steam Boilerhttps://en.wikipedia.org 15

Traveling grate spreader stoker(1)The grate moves forward towards biomass input Mass Burn Grate(2)Biomass is pushed away by the grateand burnedSource : J. P. Wolf - Lasse Rosendahl, Biomass combustion science, technology and engineering (Cambridge: Woodhead Publishing, 2013)(1) Page 230(2) Page 232Biomass Combustion System

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Bubbling Fluidised Bed (BFB)(3)Biomass is fluidized by air injected from the bottom of the boiler, burned and the ash will fall Circulating Fluidised Bed (CFB)(4)Biomass is fluidized by air injected from the bottom of the boiler, burned, circulated in boiler and the ash will fall. Better combustion resultSource : J. P. Wolf - Lasse Rosendahl, Biomass combustion science, technology and engineering (Cambridge: Woodhead Publishing, 2013)(3) Page 234(4) Page 235Biomass Combustion System

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• When burning the biomass in the boiler, ashes may melt in the furnace, eroding boiler efficiency• With furnace temperature more than 1000C, EFB, cane trash, and palm shell creates more melt ashes than other biomass fuels, thus operating temperature is kept from increasingSource: Carl Bro GroupBiomass Combustion TechnologyFuel Aspect: Avoiding Melting Ashes

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EFB/fiber composition of 20/80 has ash melting point of above 1000CAt higher EFB composition e.g. 40/60, ash melting point will be lower than 1000C:Thus GA is advised to use 20/80 composition as it would be optimum fuel mix in term of clinker avoidance and energy contentSource: Carl Bro GroupBiomass Combustion TechnologyFuel Aspect: Ash Melting Temperature of EFB

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Electricity Production Calculation 20

Feedstock : Empty Fruit Bunch (EFB) Technology: Direct combustion biomass boilerCalculation:• Palm oil mill capacity: 60 ton/hr• EFB production: 23% x 60 ton x 20 hr/day = 276 ton/day• EFB calorific value: 1200 kcal/kg (50% moisture) = 5024 kJ/kg• EFB energy generated: 5024 kJ x 276,000 kg = 1,386,624 MJ/day• Electricity conversion: 1 kWh = 3.6 MJ• Boiler Plant Efficiency = 24% • Electricity production from EFB: 1.386.624 / 3.6 x 24%: 92,441.6 kWh/day = 92.44 MWh/day• Electricity generated: 92.44 MWh / 24 hr = 3.85 MW

Biomass Consumption Calculation21

Feedstock : Wood WasteTechnology: Direct combustion biomass boilerCalculation:• Power generated = 10,000 kW (10 MW)• Operational hour per day = 24 hours• Electricity generated per day = 240,000 kWh (Note: 1 kWh = 3600kJ)• Boiler Plant Efficiency = 24% • Thermal energy required from biomass per day = (240,000 x 3600 kJ)/24%= 3,600,000,000 kJ• Average calorific value of wood waste = 9200 kJ/kg• Biomass required per day = 3600,000,000 kJ / 9200 kJ/kg = 391,304 kg≈ 400 ton/day

Biomass Consumption CalculationParameter Unit Value NotePower Generated by Turbine kW 10 968Internal Energy Consumption % 10% Proposal vendor boilerNet Plant Heat Rate (NPHR) kJ/kWh 15197.71 about 2 kg of wood per kWh. 1kWh = 3600 kJ. Plant Efficiency about 24%Electricity Generated per year kWh 80 000 000 1kWh = 3600 kJThermal Energy per year kJ 1.2158x1012Thermal Energy per month kJ 1.0132 x1011Wood Calorific Value kJ/kg 9200 Average calorific value 9200 kJ/kgWood requirement per month Ton/month 11739Wood requirement per day Ton/day ≈ 400Transportation requirement Truck/day 80 Truck Capacity 5 ton 22

Gasification TechnologyPlanning for Bioenergy Development: Potential, Technical and FinancialJakarta, 31 August 2018

Biomass Gasification Power PlantGenerating electricity by converting solid fuels into combustible gas mixture of CO + H2 + CH4 to be burned in a gas engineSource: NexterraComponent Wood gas (volume percent) Charcoal gas (volume percent)Nitrogen 50-54 55-65Carbon monoxide 17-22 28-32Carbon dioxide 9-15 1-3Hydrogen 12-20 4-10Methane 2-3 0-2Gas Heating value (kJ/Sm3) 5,000–5,900 4,500-5,600Composition of Gas From Commercial Wood and Charcoal GasifierSource: FAO (1986) 24

Process in Biomass Gasificationhttps://www.ankurscientific.com

Biomass Consumption Calculationfor 2 MW Gasification UnitFeedstock: Wood wasteTechnology: GasificationCalculation:• Power generated = 2000 kW (2 MW); Operational 24 hours per day• Electricity generated per day = 48,000 kWh (Note: 1 kWh = 3600kJ)• Efficiency of gas engine = 40%; • Thermal energy required from syngas per day = (48,000 x 3600)/40% kJ= 432,000,000 kJ• Efficiency of the gasifier = 80% • Thermal energy required from biomass per day = (432,000,000)/80% kJ= 540,000,000 kJ per day• Caloric value of biomass = 9200 kJ/kg• Biomass required per day = (540,000,000/9200) kg = 58,695 kg per day

Ash and Charcoal Utilizationhttp://rodliyahsafitri19.blogspot.com; https://alamtani.com//; https://kabartani.com; https://homeairguides.com; https://homeairguides.com

Ash and charcoal for planting media about Rp. 5000/kg Activated carbon for industrial filter and medicineRp. 30000/kg

Biogas TechnologyPlanning for Bioenergy Development: Potential, Technical and FinancialJakarta, 31 August 2018

Biogas Feedstock from Agro IndustriesSource: http://www.mesintepungindustri.com; Liquid waste from starch Liquid waste from POME (palm oil mill effluent) 29

SUBSTRATES- Organic material- Liquids (i.e. POME)- Solids- Residues Agriculture Industry Households- Energy plants PRODUCTS:Anaerobic Digestion BIOGAS- Methane (CH4)- Carbon dioxide (CO2)- H2S- Water traces (H2O)- Sludge- Fertilizer (N-P-K)Biogas Generation ProcessAnaerobic Digestion Process & Technology30

No Parameters Unit Liquid Waste StandardRange Average Ministry of Environment1 BOD mg/l 8200 - 35000 21280 502 COD mg/l 15103 - 65100 34740 1003 TSS mg/l 1330 - 50700 31170 1504 Ammonia (NH3-N) mg/l 12 - 126 41 205 Oil and Fat mg/l 190 - 14720 3075 156 pH 3.3 – 4.6 4 6-9Source: Pedoman Pengelolaan Limbah Industri Sawit, Departemen Pertanian 2006, Permen LH Nomor 3 Tahun 2010 Methane content of POME typically 20 to 25 m3/ton. BOD (Biochemical oxygen) demand is dissolved oxygen needed to break down organic material present in a given water sample at certain temperature over a specific time period. COD (Chemical oxygen demand ) is the mass of oxygen consumed per liter of solution, measured i.e. using ISO 6060 TSS (Total suspended solid)

Typical Characteristics of POMEAnaerobic Digestion Process & Technology31

Source: nachwachsende-rohstoffe.deAnaerobic Process & Biogas CharacteristicsC6H12O6 → 3CO2 + 3CH4Simplified chemical equation for anaerobic process :Elements Formula Concentration (Vol. %)Methane CH4 50-75Carbon dioxide CO2 25-45Water vapour H2O 2-7Oxygen O2 < 2Nitrogen N2 < 2Hydrogen sulphide H2S < 2Ammonia NH3 < 1Hydrogen H2 < 1 Source: Biogas Green Energy, lemvigbiogas.comAnaerobic Digestion Process & Technology

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GrowthMicroorganismRequirement: • Nutrient (macro and micro) such as C, H, O, N, S, P , Zn, Mn, Mo, Co• Environment: Temperature, pH• Enzyme, coenzyme• VitaminAnaerobic Digestion Process & Technology33

Source: Biogas Handbook, Seadi, 2008Biogas Production

34Every organics material has different biogas yield

Biogas from Solid WastesSource: Waste Solutions & KompofermSolid wastes such as EFB 35

Biogas generation from liquid waste with total solid of 0.5 to 3 %. Liquid wastes are contained in geo textile lining to capture methane released during anaerobic biological conversion. Typical Hydraulic Retention time is 30 to 60 daysSource: Waste Solutions and EPABiogas:•CO2: 25 – 45 %•CH4: 50 – 75 %•Water Vapor: 2 – 7 %•H2S < 2 %•Hydraulic Retention Time (HRT): 30 – 60 days•Total solid: 0.5 – 2 %( CIGAR )(1). Covered Lagoon Anaerobic DigesterBiogas Technology: Liquid Wastes36

The anaerobic digester contains waste water (POME), bacteria within the digesterdigest organic content of the POME, and produce methane (biogas) which iscaptured under the large cover. Capturing and utilizing the methane will reducegreenhouse gas emissions while also creating a source of renewable energySource: Univanich(1). Covered Lagoon Anaerobic DigesterBiogas Technology: Liquid Wastes37

• Total Solid: 3 – 10 %• Hydraulic Retention Time (HRT): 5 – 20 daysSource: www.daviddarling.info and IEA BioenergyBiogas generation from liquid waste with total solid of 3 to 10 %. Liquid wastes are contained in a tank to capture methane released during anaerobic biological conversion. Typical Hydraulic Retention time is 5 to 20 days(2). Complete Mix Digesters (CSTR)Biogas Technology: Liquid Wastes

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MUST BE A LONG NARROW TANKCoverWastewaterEffluent Structure Influent StructureWastewaterBiogas Storage• Total Solid: 11 – 13 %• Hydraulic Retention Time (HRT): 18 – 20 days Source: EPABiogas generation from liquid waste with total solid of 11 to 13 %. Liquid wastes are contained in a tank to capture methane released during anaerobic biological conversion. Typical Hydraulic Retention time is 18 to 20 day(3). Plug Flow DigestersBiogas Technology: Liquid Wastes

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• Hydraulic Retention Time (HRT): 0.5 – 5 days• Typical organic loading range 0.5 to 40 kg/m3/day Source: Wastewaterengineering.comBiogas generation from liquid waste with typical organic loading range 0.5 to 40 kg/m3/d. Liquid wastes are contained in a tank to capture methane released during anaerobic biological conversion. Typical Hydraulic Retention time is 0.5 to 5 day(4). UASB Reactor (Upflow Anaerobic Sludge Blanket)Biogas Technology: Liquid Wastes

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• Hydraulic Retention Time (HRT): 0.5 – 5 days• Typical organic loading range 0.5 to 40 kg/m3/day(4). UASB Reactor (Upflow Anaerobic Sludge Blanket)Biogas Technology: Liquid Wastes41

Technology Advantages DisadvantagesLarge and medium-scale technologiesComplete-mix digester (CSTR) • Compact• High solid concentration allowed • High cost• High level of technologyUASB • High COD loadings allowed• Short HRT • High cost• High level of technology• Limited to low solids concentrationCovered anaerobic lagoon • Low capital and operation cost• Simple technology• Large volume provides equalization • Requires more space• Geo membrane often not available locally• Maintenance of geo membrane cover• Limited to low solids concentrationPlug flow digester • Allow high solids concentration• Low operation cost • Undesired thermal gradients may existHRT: Hydraulic Retention TimeCOD: Chemical Oxygen DemandTechnology ComparisonBiogas Technology: Liquid Wastes

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Technology Wastes Type Construction (Months) Capital Cost($/kWe) Operation ComplexityCovered Lagoon Thin liquid(< 3 % DM) 14 to16 2200 - 3500 LowCSTR (Tank) Liquid 12 to 14 3500 - 6000 MediumConcrete Solid 24 2500 - 3000 MediumTank Solid 24 3500 - 4000 HighBiogas Technology: Liquid WastesNote: DM = Dry MatterSource: Feasibility Study – Anaerobic Digester and Gas Processing Facility in the Fraser Valley, British Columbia, Electrigaz, November 2007 with adaptation 43

Parameter Unit Abrev. Range RemarkTemperature Degree (Celcius) ̊C 35 – 3855 – 57 Mesophilic ProcessThermophilic ProcessResidence Time Day d 20 – 90 Effluent DependentConcentration (POME) COD ppm < 80,000 Mill DependentFlow rate (POME) m3 per day m3/d Mill DependentMass Flow Rate (FFB) Ton FFB per day t/d Mill DependentMethane Concentration Biogas Percentage % 50 – 75 Substrate DependentpH 6.7 – 7.5 During FermentationProcess Parameters for Biogas: POME

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45BIOGAS- Methane (CH4)- Carbon dioxide (CO2)- H2S- Water traces (H2O) •Electricity Generation•Combined Heat & Power (CHP)•Pipeline Distribution•CNG•Lighting•Vehicle fuelBIOGASPURIFICATION TREATED BIOGASIncrease:CH4 contentReduce:CO2, H2S, H2OSource: ashdenawards.blogspot.com, siwi.org, IEA

DIRECTCOMBUSTION Biogas Utilization Biogas Application •Cooking•Heating•Boiler FuelUTILIZATION

Technology Cost Efficiency Complexity ReliabilitySimple CombustionBurner Low High Low HighBoiler Low High Low HighElectricalGenerator High Medium Medium HighTurbine High Medium High MediumBiogas Upgrading Very high High High VariableSource: Feasibility Study – Anaerobic Digester and Gas Processing Facility in the Fraser Valley, British Columbia, Electrigaz, November 2007Biogas Application

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The biogas from digester is first cleaned of impurities such as H2S and traces of waterthen consumed by gas engines to generate electricity.Source: BioGasCleanH2S ScrubberGas Engine Demoisturizer

H2S Scrubber, Demoisturizer & Gas EngineElectricity Generation from Biogas47

• Stoichiometry for complete oxidation of Methane:CH4 + 2O2 ----------- 2H2O + CO21 kmol CH4 (= 16 kg) requires 2 kmol of O2 or Oxygen Demand (=64 kg)• 64 kg of Chemical Oxygen Demand (COD) will produce 16 kg of Methane (CH4), therefore 1 kg COD = 0.25 kg Methane. • At 0oC and 1 bar (STP), 1 kmol CH4 has 22.4 Sm3. Therefore 1kg O2oxidizes 0.35 Sm3 or 0.25 kg of methane. (Theoretical)Note: Molecular weight of carbon (C) = 12, Hydrogen = 1, Oxygen = 16Conversion of COD into Methane

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Example:• Palm Oil Mill capacity 45 ton/h. • Assuming 1 ton of fresh fruit bunch (FFB) generates 0.65 m3of palm oil mill effluent (POME) and • Mills operate at 20 h/day• POME COD of 60000 mg/l, • Efficiency of COD conversion into biogas of 84%, • Methane concentration of 55%, • Electrical efficiency of gas engine at 38%• Biogas plant yearly operation at 7200 h. Electricity Production Calculation49

The calculation of electricity generated from a mill with capacity of 45 ton/h fresh fruit bunch is as follows:• Daily POME Flow: 45 ton FFB/hr x 20 hr/day x 0.65 m3 POME/ton FFB = 585 m3/day• COD Loading: 60000 mg/l x 585 m3/day x (1/1000000) kg/mg x 1000 l/m3 = 35100 kg/day• CH4 production: 35100 kg/day x 0.35 Nm3/kg x 0.84 = 10319.40 Nm3/d• Power Generation Capacity: 10319.40 m3/d x 35.7 MJ/Nm3 x 0.38 x 1/(24x60x60) d/s = 1.62 MWeCOD to Methane conversion: 0.35 Nm3 methane/kg CODMethane energy value: 35.7 MJ/Nm3 50Electricity Production Calculation

Notes: Electricity generated from POME biogas depends on amount of waste water flow and COD level. Every palm oil mill has their own COD level. In this calculation assumed COD is 60,000 mg/l. Description Unit 30 tph 45 tph 60 tphAnnual FFB tones FFB/year 180,000 270,000 360,000 Daily throughput tones/day 600 900 1,200 Effluent rate % 0.65 0.65 0.65 Daily water flow m3 390 585 780 Typical COD mg/l 60,000 60,000 60,000 Conversion to methane Nm3 CH4/kg COD 0.35 0.35 0.35 COD convesion estimate 0.84 0.84 0.84 Methane production estimate Nm3 CH4/day 6,879 10,319 13,579 Assumed methane content % 0.55 0.55 0.55 Biogas flow hourly m3/h 459 669 918 Methane energy value MJ/m3 35 35 35 Average generation efficiency % 38% 38% 38%Continuous generation capacity MWe 1.08 1.62 2.16Internal consumption MWh/day 2.14 2.14 2.14 Availability factor % 0.90 0.90 0.90 Electricity sold to grid MWh/year 7,813 12,071 16,329

Typical Electricity Generated from POME Biogas

Thank you“Planning for Bioenergy Development: Calculation of Technical Potential and Financial Aspects”Jakarta, 31 August 2018yuwono.hari@gmail.com