A comparison of pipeline versus truck transport of bio-oil

Biomass-based energy and fuels are receiving attention because they are considered carbon neutral; i.e. the amount of CO2 released during combustion of this biomass is nearly the same as that taken up by the plants during their growth. Bio-oil is a dark viscous liquid consisting of hydrocarbons. These are produced by fast pyrolysis of biomass. “As-is” biomass material has a low energy density (MJ m−3), hence, the cost of transporting this energy is high. Bio-oil has a high energy density as compared to “as-is” biomass material, consequently it helps in reducing the cost of energy transport. This study compares the life cycle assessment of transportation of bio-oil by pipeline with that by truck. The scope of the work includes the transportation of bio-oil by truck or pipeline from a centralized plant (supplied with forest biomass) to an end-user. Two cases are studied for pipeline transport of bio-oil: the first case considers a coal-based electricity supply for pumping the bio-oil through a pipeline; the second case considers an electricity supply from a renewable resource. The two cases of pipeline transport are compared to two cases of truck transport (truck trailer and super B-train truck). The life cycle greenhouse gas (GHG) emissions from the pipeline transport of bio-oil for the two cases of electricity supply are 345 and 17 g of CO2 m−3 km−1, respectively. Similar values for transport by trailer (capacity – 30 m3) and super B-train truck (capacity – 60 m3) are 89 and 60 g of CO2 m−3 km−1, respectively. Energy input for bio-oil transport is 3.95 MJ m−3 km−1 by pipeline, 2.59 MJ m−3 km−1 by truck and 1.66 MJ m−3 km−1 by super B-train truck. The results show that GHG emissions in pipeline transport are largely dependent on the source of electricity (higher for coal-based electricity). Substituting 250 m3 day−1 of pipeline-transported bio-oil for coal-based electricity can mitigate about 5.1 million tonnes of CO2 per year. Overall, this study gives a comprehensive life cycle assessment of bio-oil transport comparing pipeline and truck transport.