A Life Cycle Assessment of the Biomass-to-Liquid Considering the Fuel Consumption of a Truck

Abstract

In this paper, we focused on BTL (Biomass-to-Liquid) fuel for trucks which is synthesized from woody biomass feedstock, and discussed the alternative potential of BTL for the purpose of mitigation of CO₂ emission in a transportation sector. Here, we estimated the specific CO₂ emission of BTL fuel and the energy intensity of BTL production system on basis of "Well-to-Wheel" concept, so-called LCA methodology. So far, there are some examples of the life cycle inventory in the transportation sector. However, many of those are based on the literature review. Based on the results of basic experiments, demo-plant operation and test-run of truck, the data of the energy production phase ("Well-to-Tank") and the fuel consumption of target truck ("Tank-to-Wheel"), which is extremely important, were used in our estimation. Here, in order to examine the possibility of low-emission fuel promotion as alternative diesel, we focused on following four Bio-fuels; Bio-H₂, Bio-DME (Di-Methyl Ether), Bio-MeOH, and Bio-FTD (Fischer-Tropsch Diesel). Considering the energy density of biomass feedstock in the domestic area, we selected BLUE Tower gasification process (BT process, standard plant scale: 15 t/d) which will be close to the practice stage. Also, the characteristic of syngas through BT process has the concentration ratio of H₂:CO=2:1, which would be suitable for synthesizing BTL fuels. Through our life cycle stages, we estimated CO₂ emission [g-CO₂/km] in 4-ton trucks case. The performance data such as fuel consumption was measured in the driving test on JE05 mode which is based on the change of speed in urban area, adopted as the official mode to measure exhaust gas emissions and fuel consumption of a heavy duty car on a chassis dynamometer in Japan. Note that the fuel consumption data of H₂ and MeOH trucks were assumed due to the results of past, present and/or overseas R&D activities. Compared with the CO₂ emission of conventional fuel (Diesel: 443.43 g-CO₂/km), the mitigation benefit was obtained under the minimum emissions conditions (i.e. H₂: 266.53 g-CO₂/km, MeOH: 391.95 g-CO₂/km, DME: 274.72 g-CO₂/km, FTD: 291.28 g-CO₂/km).