Biogas has least impact, study finds (Lithuania)

By Jan Christiaens / Updated: 01 Aug 2014
A Lithuanian study of the “well to wheel” environmental impacts of various fuels used in buses found that locally produced biogas was best.
The study compared the environmental impacts of the fuels using a lifecycle assessment approach. It covered impacts associated with extraction, transportation, production, distribution and use. The buses studied included diesel-powered buses, compressed natural gas buses, compressed biogas (locally sourced) buses and trolleybuses powered by electricity generated from natural gas or heavy fuel oil.

Implemented by the Department of Environmental Engineering, Kaunas University of Technology, the study focused on the local municipality, where public transport has a 60 percent modal share.

The compressed biogas fuel chain had the lowest weighted damage value: 45.7 millipoints per kilometre (mPt/km). Because Kaunas’s biogas is sourced locally from a wastewater treatment plant, it has minimal resource extraction impacts compared to those for non-renewable resources such as oil and natural gas.

The figures for trolleybuses were 60.6 mPt/km (electricity from natural gas) and 78.9 mPt/km (electricity from heavy fuel oil). The diesel and compressed natural gas fuel chains had considerably higher damage values of 114.2 mPt/km and 132.6 mPt/km, respectively.

Compressed biogas buses actually consumed the most fuel of the buses studied, but since their emissions are biological in origin, they were not considered as harmful as fossil fuel buses. The lowest consumption was in trolleybuses using electricity generated from natural gas. Using natural gas to produce electricity for trolleybuses was almost twice as energy-efficient as using natural gas to directly power the buses.

Source: Click Green

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