Powering refuse collection vehicles (RCVs) using biomethane can deliver both greatly reduced greenhouse gas (GHG) emissions and cost savings for UK local authorities. These are the findings of a yearlong trial of the fuel by Leeds City Council, which received technical advice from Cenex.

The trial vehicle, a Mercedes-Benz Econic LLG with a spark ignition engine running solely on biomethane gas, is estimated to have achieved a 49 per cent saving in well-to-wheel GHG emissions, compared to the diesel Econics in the council’s fleet. However, this was achieved using a temporary filling station – a more efficient permanent station raises the GHG saving to 64 per cent, with possible 78 per cent savings estimated if gas was generated on-site. Additionally, lower fuel expenditure meant that annual vehicle running costs were estimated to be £2,500 less than a diesel equivalent. While gas vehicles currently cost more to purchase than diesel RCVs, this gap is expected to narrow as production increases.

Given this success, Leeds City Council has extended the trial for a further three to five years. With the assistance of the Infrastructure Grants Programme the council has installed a permanent filling station, and hopes to eventually increase the number of gas vehicles within its 1,100 strong fleet.

Extrapolating the results of this trial across the UK fleet of RCVs demonstrates the potential for biomethane as a fuel. Using gas produced from either landfill sites or purpose built anaerobic digesters would save around 80 per cent of emissions compared to diesel, as well as delivering substantial cost savings, due to factors such as the rising cost of diesel and the falling purchase cost of biomethane vehicles.

Leeds City Council began the trial following a review of its total vehicle fleet. This Green Fleet Review showed that while RCVs made up just seven per cent of its fleet, they were responsible for 25 per cent of total fuel use. Following advice from Cenex, biomethane was identified as showing the greatest potential for achieving the necessary savings.

Richard Crowther environmental assessment officer in transport policy at Leeds City Council said, “We’ve already done a great deal to improve the efficiency of our fleet vehicles and reduce unnecessary mileage, but we’ve reached a point where that in itself won’t be enough to meet our environmental targets. We knew we needed to embrace low carbon technologies too and turned to Cenex for independent advice. This successful trial shows the enormous potential for switching sections of our fleet over to gas technology and we look forward to further savings following its extension.”

Biomethane is a gas that is around 95 per cent methane. Anaerobic digestion of biological material produces a mixture of gases typically referred to as biogas – the three main sources in the UK are landfill gas, sewage gas and gas produced by purpose built anaerobic digesters fed with farm and municipal food waste. As the methane content of biogas varies between 30-65 per cent, a variety of technologies are used to purify and concentrate the methane in biogas, producing biomethane. As it is produced from renewable sources, biomethane is considered to have zero net carbon emissions at the point of use. This means it offers much higher potential GHG savings compared to natural gas.

Chris Walsh, head of technical support and consultancy at Cenex, said, “In the UK, heavy goods vehicles such as refuse trucks contribute a disproportionately high percentage of carbon dioxide emissions. With a pressing need to reduce greenhouse gases, it is imperative that we explore the use of new fuels such as biomethane wherever feasible. This pioneering Leeds City Council trial highlights the major advantages of switching the UK’s RCV fleet to run on biomethane.”