Biomass to liquid: A prospective challenge to research and development in 21st century

The biomass to liquid refineries need to build on the need for sustainable chemical products through modern and proven green chemical technologies such as bioprocessing including pyrolysis, Fisher Tropsch, and other catalytic processes. This review focuses on cost effective technologies and the processes to convert biomass into useful liquid biofuels and bioproducts. One of the most promising options to produce transportation fuels from biomass is the so-called biomass to-liquid (BTL) route, in which biomass is converted to syngas from which high-quality Fischer–Tropsch (FT) fuels are synthesized. Pretreatment of biomass is an important part of the BTL route, both to allow feeding of the biomass into the selected entrained-flow gasifier and to reduce transport costs by densification. A large-scale, central, overseas BTL synthesis plant would be the most attractive route for BTL production and it identifies biomass-to-liquid (BTL) fuels as the most promising way to accomplish the target. The evaluation of the future role of BTL is difficult due to complex and uncertain interdependencies between factors of influence. This study elaborates a life cycle assessment of using of BTL-fuels and 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 28–69% with the BTL-processes using straw, forest wood or short-rotation wood as a biomass input. The reduction potential concerning non-renewable energy resources varies between 37% and 61%. BTL-fuel from forest wood is an interesting option to reduce the greenhouse gas emissions and environmental impacts. The 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.