What is biomethane?
Biogas is a gas, largely consisting of methane and carbon dioxide, created during the breakdown of organic material such as waste, manures, sewage and energy crops. When biogas is purified to > 95% methane content it is called biomethane. Biomethane offers a sustainable replacement, and can be directly substituted, for natural gas. Biomethane can be used as an alternative automotive fuel to petrol and diesel.
Why conduct a Biomethane trial?
Natural gas is used extensively throughout the world as a transport fuel. It is estimated that around 13.5 million natural gas vehicles are currently in use, with over 1 million of these operated in Europe. However uptake in the UK has been slow and fleet managers have little or no experience of these fuels.
To understand some of the issues affecting the replacement of natural gas by biomethane a trial was undertaken in the London Borough of Camden comparing street cleaning vehicles fuelled by natural gas and biomethane.
Who was involved?
Cenex offered financial and evaluation support to the trial. Veolia Environmental Services operated and monitored the performance of the vehicles on a street cleansing round in the London Borough of Camden. Gasrec supplied both the biomethane from their upgrading facility at an Albury landfill site, and a biomethane fuelled Iveco Daily. Iveco, the vehicle manufacturer provided technical support to the trial.
What were the results?
The CO2 emission savings when switching from natural gas to biomethane were conservatively calculated to be 56%. Although a diesel comparison vehicle was not used in the trial, evidence suggests that a further circa 10% CO2 saving could be achieved if comparing biomethane to a diesel equivalent giving an approximate CO2 saving of 66%.
No maintenance issues were experienced with the vehicles during the trial and the oil analysis showed no evidence of accelerated engine wear or insoluble deposits out with normal working levels.
The biomethane supplied by Gasrec for the trial had high methane (98%) content with a low level of contaminants with the potential to wear components - siloxanes and hydrogen sulphide.
Type approval figures for the vehicles reveal that air quality emissions from the Iveco natural gas vehicle on the legislated cycle are below the proposed limits for future Euro VI legislation. Notably PM and NOx are 30% and 53% below these levels respectively.
The newer model Iveco Daily operating on biomethane displayed an overall 6% reduction in fuel consumption despite operating on a more onerous route.
Can I read the detailed project report?
Yes, the full report entitled Camden Biomethane Trial Report is available from the Resources page.