BASIC DATA ON BIOGAS - SGC

1 BASIC DATAON BIOGASS wedish Gas Technology Centre Ltd (SGC)Scheelegatan 3SE-212 28 MALM SGC 20122ndedition1000 copiesPrinted on Munken Pure 100g/m Print: Servicef rvaltningen i Lunds kommun, LundISBN: 978-91-85207-10-7 PrefaceRenewable gases such as BIOGAS and biomethane are considered as keyenergy carrier when the society is replacing fossil fuels with renewablealternatives. In Sweden, almost 80 % of the fossil fuels are used in thetransport sector. Therefore, the focus in Sweden has been to use theproduced BIOGAS in this sector as vehicle Data on Biogascontains an overview of production, utilisation,climate effects etc. of BIOGAS from a Swedish perspective. The purpose is togive an easy overview of the current situation in Sweden for politicians,decision makers and interested public. Swedish Gas Technology Center Ltd(SGC) has been responsible for the writing with financial support from AvfallSverige, Energigas Sverige, Gas Sverige AB, Greenlane BIOGAS AB,G teborg Energi AB, LRF, Lunds Energikoncernen AB, L ckeby Water AB,Malmberg Water AB, NSR AB, Processum Biorefinery Initiative AB,Stockholm Gas AB, Svensk BIOGAS i Link ping AB, Svenskt Vatten andSwedish energy Agency.

2 The translation has also been supported by EUthrough Biomethane Regions and Intelligent energy assignment of SGC is to co-ordinate the Swedish industrial interest inR&D focused on gas fuel technology. This is performed on a non profit Swedish government represented by the Swedish energy Agencyparticipates in financing the R&D-program. SGC was established in 1990. Formore information, please visit, publication is an updated version ofBasic Data on BIOGAS , that waspublished for the first time in Gas Technology Centre: BASIC Data on BiogasProduction of TWh of BIOGAS is produced annually in Sweden at approximately 230facilities. The 135 wastewater treatment plants that produce biogascontribute with around half of the production. In order to reduce the sludgevolume, BIOGAS has been produced at wastewater treatment plants fordecades. New BIOGAS plants are mainly co-digestion plants and farm landfilling of organic waste has been banned since 2005, thus thebiogas produced in landfills is : Swedish energy Agency, Produktion och anv ndning av BIOGAS r 2010; ES2011:07 BIOGAS plantsNumberEnergy in BIOGAS [GWh/year]Wastewater treatment plants135614Co-digeston plants18344 Farm plants1416 Industrial wastewater5114 Landfills57298 Sum2291 3871 Swedish Gas Centre: BASIC Data on BiogasSubstratePotential biogasproduction withlimitations*[TWh]Total biogaspotential[TWh]Food from parks and waste and residues(including food industry) from wastewater residues and manure** BIOGAS productionThere is a large potential to increase the Swedish BIOGAS production asbiogas can be produced from various types of substrates that are currentlytreated as residues or waste .

3 Agricultural residues represent the greatestpotential resource. The theoretical potential BIOGAS production in Swedenhas been estimated to be more than 15 TWh/year, which is around tentimes more than the current production.*Taking into account limitations in todays technical and economical situation.** TWh of this potential origins from straw which requires pretreatment before : Den svenska biogaspotentialen fr n inhemska restprodukter, can also be produced from crops. This potential is difficult to estimateand depends entirely on which assumptions are made regarding land use, cropand yield. If 10 % of the agricultural land in Sweden is used, approximately 7 TWh of BIOGAS could be produced annually.(Source: Biogaspotential och framtida anl ggningar i Sverige, 1998)Swedish Gas Centre: BASIC Data on BiogasThe BIOGAS processBiogas, which is mainly composed of methane and carbon dioxide, isproduced during the decomposition of organic matter in anaerobicconditions.

4 The organic matter is decomposed in a number of steps in acollaboration between several different types of microorganisms. Theefficiency of the BIOGAS production depends on how suitable the conditionsare for the microorganisms. To initiate a BIOGAS process, sludge containingthe bacteria for starting the process is inoculated from an existing BIOGAS process divided into a number of stages that take place duringdigestion. (Illustration:Energigas Sverige)3 Swedish Gas Centre: BASIC Data on BiogasParameters for the BIOGAS processLoading rateAmount of substrate added to the digester. kg VS per m3digester and productionAmount of produced BIOGAS between carbon and nitrogen content in to digestion, many substrates needs to bepretreated. This pretreatment can be pasteurisation,thickening or Solids VSWeight of organic matter in the substrate. Normallyexpressed as percentage of at 25 40 C. Usually around 35 37 of methane in the BIOGAS .

5 Normally expressedas percentage by yieldAmount of produced methane at 50 60 C. Usually around 50 55 Solids TSThe weight of the substrate after drying. Normallyexpressed as percentage of wet weight. Also called drymatter (DM)Dry DigestionDigestion of substrate with TS around 15 35 %.Hydraulicretention timeThe average time that the substrate is inside of VSDescribes how much of the substrate that is degradedin the digester. Usually expressed as percentage of digestionDigestion of substrate with TS around 2 15 %.Wet weightThe weight of the substrate including Gas Centre: BASIC Data on BiogasBiogas production for different substratesThe BIOGAS production varies between different substrates depending onthe composition of the substrate. The BIOGAS production figures in the tablebelow are determined in laboratory scale and therefore higher thanexpected during continuous operations in full productionMethaneconcentration[%][m3/ton TS][m3/tonwet weight ][%]Sludge from waste -water treatment plants53001565 Fish waste421 27953771 Straw7826520770 Sorted food waste3361820463 Liquid cattle manure92442265 Potato haulm154536856 Slaughter house waste165759263 Liquid pig slurry83252665 Sources: Substrathandbok f r biogasproduktion, SGC 2009 Den svenska biogaspotentialen fr n inhemska restprodukter, 2008 kad biogasproduktion vid Henriksdals reningsverk, 20095 Swedish Gas Centre.

6 BASIC Data on BiogasBiogas production from cropsBiogas production in Sweden could be greatly increased by using are given in the table )TSMethane yieldSubstrateneedLandrequirement[ton/ha and year][% of wetweight][Nm3methane/ tonwet weight][ton/GWh][ha/GWh]Jerusalemarticho ke2)602248150025 Maize433095107025 Potato2625100102039 Sugar beet3)502494109022 Grass223595110050 Wheat )Harvest quantities are valid in the area of M )Data is valid for harvest of )Harvest quantities are valid in the area of Sk : , 2011-02-156 Swedish Gas Centre: BASIC Data on Biogas7 Composition of biogasThe composition of BIOGAS depends on a number of factors such as theprocess design and the nature of the substrate that is digested. The maincomponents are methane and carbon dioxide, but several othercomponents also exist in the BIOGAS . The table below lists the typicalproperties of BIOGAS from landfills and digesters as well as a comparisonwith Danish natural :Energigaser och milj , SGC , , 2011-02-15 Landfill gasBiogas from ADNatural gasLower calorific valueMJ/Nm3162339 index, upperMJ/Nm3182755 Methane number>130>13573 MethaneVol-%456590 Methane, rangeVol-%35 6560 7085 92 Heavy hydrocarbonsVol-%009 HydrogenVol-%0-30 Carbon dioxideVol-% dioxide, range Vol-%15 4030 , rangeVol-%5 40 Oxygen, rangeVol-%0 5 Hydrogen sulphideppm<100< sulphide,rangeppm0 1000 Total chlorine as Cl-mg/Nm320 2000 5 Swedish Gas Centre: BASIC Data on BiogasUpgrading of biogasTo increase the energy density of the BIOGAS , it is possible to upgrade it withdifferent technologies.

7 In practice, this is performed by removing themajority of the carbon dioxide. Examples of techniques are given in thetable SwingAdsorption (PSA)Adsorption of carbon dioxideon activated scrubberAbsorption of carbon dioxidein andcounter flow of reaction betweencarbon dioxide and amine based through amembrane that is permeablefor carbon dioxide. CryogenicseparationCooling until condensation orsublimation of the carbondioxide To increase the energy density even further, it is possible to condense thebiogas by cryogenic cooling. Liquified BIOGAS is normally abbreviated Gas Centre: BASIC Data on BiogasEnergy content of biogasA typical normal cubic meter of methane has a calorific value of around 10kWh, while carbon dioxide has zero. The energy content of BIOGAS istherefore directly related to the methane concentration. In other words,assuming a BIOGAS composition with 60% methane, then, the energycontent would in this case be around kWh per normal cubic : , , 2011-02-15 Preem, , 2011-02-15 This in turn implies that the energy content in 1 Nm3biogas corresponds toaround litre petrol and the energy content in 1 Nm3natural gascorresponds to around litre the figure below, the volumes of compressed (200 bar) and liquefiedbiogas with the same energy content as 1 liter petrol are litre litre biogas200 litre LBG9 Vehicle fuelEnergy content [kWh]1 Nm3upgraded BIOGAS (97 % methane) Nm3natural litre litre litre E85(vehicle fuel with 85%ethanol and 15% gasoline) (summer, 85% ethanol) (winter, ethanol)Swedish Gas Centre.

8 BASIC Data on BiogasMethaneMethane is the simplest alkane and consistsof one carbon atom and four hydrogen atomsand is probably the most abundant organicmolecule on , , liquidekg/m3423 Upper calorific calorific index, index , range% point C exists several safety aspects that need to be considered duringproduction and handling of BIOGAS . It is very important to be aware of therisks and to minimise these. The most common risks are: Flammability Poisoning (mainly H2S) Suffocation Risks caused by high pressures Thermal injuriesAs the density of upgraded BIOGAS is lower than air, any gas leaking will riseupward. In addition, upgraded BIOGAS has a higher temperature of ignitionthan both petrol and diesel. This means in turn that the risk of fire orexplosion in traffic accidents is smaller for upgraded BIOGAS than for petrolor : Encycopedie des Gaz, L air LiquideSwedish Gas Centre: BASIC Data on BiogasUtilisation of biogasThe annual energy use in Sweden is around 600 TWh and it origins mainlyfrom four energy carriers: oil (187 TWh), nuclear power (166 TWh), biofuels(141 TWh) and hydro power (67 TWh).

9 The annual energy use, withoutconversion losses, is estimated to around 400 of the 117 TWh oil (without conversion losses) that is used annually inSweden, almost 80% is used in the transport sector, which makes this sectorthe most fossil fuel depending sector. Electricity and heat production ismainly produced from non-fossil energy carriers. This makes the utilisationof BIOGAS as a vehicle fuel the best way to decrease the fossil fueldependency in can be used in many ways. Typical applications in Sweden include:HeatThe gas is combusted in a boiler. The heat generated warms upwater which can be used to heat the digester and nearbybuildings or be exchanged on a local district heating network. Agas boiler works like a boiler for solid and liquid fuels, but withthe difference that the boiler is specially modified to can be used as a fuel in stationary engines, typically Ottoor diesel engines, or gas turbines.

10 About 30-40% of the energyin the fuel is used to produce electricity while the remainingenergy becomes fuelBiogas can be used as a vehicle fuel for cars, buses and trucks,providing it is upgraded by removing carbon dioxide, water andhydrogen sulphide. Water scrubbing, chemical scrubbing andPSA are the most widely used techniques for upgrading biogasto vehicle fuel quality. The gas must also be odourised andpressurised to around 200 bar before it can be used as BIOGAS can also be introduced into the national gas grid, whichwill stimulate the development of new markets and Gas Centre: BASIC Data on BiogasIn 2010, the utilisation of BIOGAS was divided according to the diagrambelow:Source: Produktion och anv ndning av BIOGAS r 2010; ES2011 44%Electricity 4%Upgradedbiogas 44%Flaring8%No data< 1%Swedish Gas Centre: BASIC Data on BiogasBiogas as vehicle fuelDue to the dependency of fossil fuels in the Swedish transport sector,utilisation of BIOGAS as vehicle fuel has gained large interest during the lastfew years.