The new CCE gas fleet will consume approximately 168 tonnes of biomethane saving more than 300 tonnes of CO₂, 1,590 kg of NO_x and 33 kg of PM emissions per year.

CCE contracted Cenex to evaluate and compare the emissions, fuel consumption, economics, reliability and operability of a 26-tonne Iveco Stralis gas vehicle with that of a diesel Stralis vehicle. The trial vehicles—one operating solely on biomethane gas, and one diesel-powered—were highly comparable. Both were new registrations at trial commencement and met Enhanced Environmentally friendly Vehicle emission standards (emission levels between the current Euro V standard and the future (2013) Euro VI levels).

The gas vehicle had a small payload penalty of 700 kg due to the additional weight of the fuel tanks. The gas vehicle was supplied with a fully automatic gearbox whereas the diesel vehicle incorporated an automated manual transmission.

Biomethane is the term given to biogas that has been upgraded (i.e. unwanted gases and contaminants have been removed) to vehicle fuel quality which typically has a high > 95% methane (CH₄) content. Biogas is created from the anaerobic digestion of organic matter and contains approximately 60% CH₄ and 40% carbon dioxide (CO₂), plus very small quantities of oxygen (O₂), carbon monoxide (CO), and nitrogen (N₂).

The amount of CO₂ produced by combusting biomethane is similar to the amount of CO₂ absorbed by the organic matter during its growth. The release of this CO₂ is part of a sustainable carbon cycle—hence, biomethane is a renewable fuel. The UK is one of the largest producers of biogas from landfill sites in Europe.

A temporary gas vehicle refueling infrastructure was installed at the CCE depot in Enfield, UK from which the trial vehicles were operated. Vehicle activity data from the Enfield depot was logged via onboard telemetry. The CCE drive cycle was a 30-minute, 19.5 km cycle statistically representative of vehicle distribution patterns from Enfield. Testing vehicles over the CCE drive cycle in an emissions testing facility allowed air quality performance as well as tailpipe CO₂ and fuel consumption to be measured in a controlled and repeatable environment.

Among the findings of the study were:

• Biomethane gas vehicle operation reduced NO_x and PM emissions by 85.6% and 97.1% respectively.

• The gas vehicle achieved a 50.3% saving in well-to-wheel GHG emissions, compared to the diesel Stralis vehicle. However, this was achieved using a temporary filling station—a more efficient permanent station being installed at the CCE depot raises the GHG saving to 60.7%.

• The gas truck consumed 34.9 kg/100 km compared to the diesel truck that consumed 31.9 liters/100 km (7.4 mpg US) over the CCE drive cycle. This equated to a theoretical vehicle range of 357 km and 940 km (222 and 584 miles) for the gas and diesel trucks respectively.

• The overall reduction in efficiency from the diesel to gas vehicle over the CCE drive cycle was 31.8%.

• The gas vehicle achieved an availability rate of 99.2% during the 12 month vehicle trail compared to an availability rate of 100% for the diesel vehicle.

• Gas vehicle operation reduced noise levels by 4.1 dB(A), 10.5 dB(A), and 8.1 dB(A) during low speed drive-by, engine idle and hot engine start conditions respectively.

• Drivers rated the overall performance of the gas vehicle higher than the diesel. Drivers were most impressed with the gas trucks acceleration, transmission and refueling aspects.

• Operating the gas vehicle on biomethane reduced the fuel costs by 12.8%. However, the total cost of ownership increased by 15.3% primarily due to the additional capital cost of the gas vehicle. Estimated future cost reductions between the vehicle technologies coupled with a further reduction in gas price due to either a higher volume supply or the use of a public gas refueling station would achieve a similar total cost of ownership between the two vehicle technologies.

Resources

• The Coca-Cola Enterprises Biomethane Trial Report