Full life cycle from wheel-to-street using Biomass-to-Liquid Fuels
This study elaborates a life cycle assessment of using of BTL-fuels (biomass-to-liquid). This type of fuel is produced in synthesis process from e.g. wood, straw or other biomass. The life cycle inventory data of the fuel provision with different types of conversion concepts are based on the detailed life cycle assessment compiled and published within a European research project.
The inventory of the fuel use emissions is based on information published by automobile manufacturers on reductions due to the use of BTL-fuels. Passenger cars fulfilling the EURO3 emission standards are the basis for the comparison. The life cycle inventories of the use of BTL-fuels for driving in passenger cars are investigated from cradle to grave. The full life cycle is investigated with the transportation of one person over one kilometre (pkm) as a functional unit. This includes all stages of the life cycle of a fuel (biomass and fuel production, distribution, combustion) and the necessary infrastructure (e.g. tractors, conversion plant, cars and streets).
The use of biofuels is mainly promoted for the reason of reducing the climate change impact and the use of scarce non-renewable resources e.g. crude oil. The possible implementation of BTL-fuel production processes would potentially help to achieve this goal. The emissions of greenhouse gases due to transport services could be reduced by 28% to 69% with the BTL-processes using straw, forest wood or short-rotation wood as a biomass input. This is lower than the 90% CO2-reduction claimed in earlier studies. The reduction potential concerning non-renewable energy resources varies between 37% and 61%.
A previous study showed that many biofuels cause higher environmental impacts than fossil fuels if several types of ecological problems are considered. The study uses two single score impact assessment methods for the evaluation of the overall environmental impacts, namely the Eco-indicator 99 (H,A) and the Swiss ecological scarcity 2006 method. The transportation with the best BTL-fuel from short-rotation wood has only slightly higher environmental impacts than the reference under an evaluation with the ecological scarcity 2006 method. BTL-fuel made from agricultural by-products like straw can achieve environmental impacts similar to petrol if the Eco-indicator 99 (H,A) is evaluated. BTL-fuel from forest wood is an interesting option to reduce the greenhouse gas emissions and environmental impacts.
This LCA study shows that it is possible to produce BTL-fuels, which are competitive to fossil fuels from an environmental point of view. But, it also shows that for the use of agricultural biomass further improvements in the life cycle would be necessary in order to avoid higher environmental impacts than for fossil fuels. There is no general conclusion concerning the comparison of BTL-fuels with other renewable or fossil fuels due to the variety of different conversion concepts and possible biomass resources.
download: homepage of BFE, PDF-file
Jungbluth, N., Büsser, S., Frischknecht, R., Tuchschmid, M. 2008: Ökobilanz von Energieprodukten: Life Cycle Assessment of biomass-to-liquid fuels. Programm Biomasse No. 280006, ESU-services Ltd. im Auftrag des Bundesamt für Energie, Bundesamt für Umwelt und Bundesamt für Landwirtschaft, Berne, CH
