Biomethane for use as a transport fuel
Biomethane for transport is one of the options being supported by the European Green Cars Initiative (a €5 billion PPP boost to the European car industry).
Biogas is a mixture of biomethane CH4 (65-70%) and CO2 (30-35%) and small amounts of other gases. It is created by anaerobic digestion of organic wastes such as sewage, manure, food wastes, landfill, etc. This is an established technology. After removal of contaminants, biomethane is the same as natural gas, and can be used as a transport fuel in the form of Liquid Natural Gas (LNG) or Compressed Natural Gas (CNG).
Bio-SNG (Bio Synthetic Natural Gas) is produced by gasification of lignocellulosic (woody materials). A number of Bio-SNG demonstration projects are discussed on this website.
Anaerobic Digestion technology is well established, hence biogas is generally considered as a first generation biofuel. However, when biogas is derived from organic wastes and not crops, is is considered to be sustainable. Biomethane for transport is the focus of several projects such as MADEGASCAR, GasHighWay and BioGas Max, which aim to increase its use in the market.
Use of gas as a transport fuel in Europe
Gas is widely used as a transport fuel in many European countries, notably Italy, which boasts 650,000 gas powered vehicles. Sweden is a world leader in upgrading and use of biomethane for transport, and has many 'biogas vehicles', including private cars, buses, and even a biogas train and a biogas powered touring car team.
© Copyright
E.ON www.biogas.se
To promote the potential of biomethane
as a transport fuel, E.ON has entered the 2009 Swedish
Touring Car Championship (STCC) with two gas-driven Volkswagen Sciroccos.
E.ON is Sweden’s leading player in biogas. The company produces
biogas, builds refueling stations and sells biogas. View
at larger size >>
Pretreatment of agricultural residues for enhanced production of biogas
Researchers at the Fraunhofer Institute IKTS, Germany, have developed the first-ever biogas plant to run purely on agricultural wastes. This demonstrates that pretreatment with enzymes can greatly increase biogas yields from cellulosic residues such as corn stalks.
In China, 3 pilot facilities have been built to demonstrate the production of biogas from rice straw pretreated with Sodium Hydroxide.
With 23 day anaerobic digestion at mesophilic temperature of 35°C, rice straw pretreated with 10% NaOH at 20°C for 24 hours had the biogas yield of 0.6 L /g VS, 50% higher than the biogas yield from untreated straw. After enzymatic hydrolysis using cellulase from Trichoderma reesei ATCC 26921 and cellobiase from Aspergillus niger, the pretreated straw had the reducing sugar yield of 298 mg glucose/g VS, 185% higher than the untreated straw (Source: Dong Yang et al, published April 2009 American Society of Agricultural and Biological Engineers)
Methane Slip and certification
If methane is accidentally released into the atmosphere, it is much more damaging than carbon diocide as a GHG. In 2008, the Naturemade certification system was initiated in Switzerland to guarantee the ecological quality of the biomethane injected into the grid. To qualify, the emission of biomethane (also known as 'methane slip') must not exceed 1% of the total biomethane generated by a plant. (Source: BioGas Max)
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UEA
In the UK, the University
of East Anglia (UEA) Low Carbon Innovation
Centre (LCIC) and Hardstaff
Group (Nottingham, UK), have modified a standard Optare Solo single-deck
diesel midibus from the Anglian Bus fleet. Originally powered entirely by
diesel, the Mercedes-Benz engine has been adapted to run for 60-80 per cent
of the time on biomethane.
Further links on biogas R&D&D in Europe
The following links provide further information on EC R&D&D on Biogas production and its use as a transport fuel:
MADEGASCAR - Market development for gas driven cars
UK Anaerobic Digestion and Biogas portal
Biogas as a Road Transport Fuel Report
IEA Task 37 - Energy from Biogas and Landfill Gas
Biogas Upgrading to Vehicle Fuel Standards and Grid Injection