Biomass to Liquids
The term BtL (Biomass to Liquids) is applied to synthetic fuels made from biomass through a thermochemical route. The objective is to produce fuel components that are similar to those of current fossil-derived petrol (gasoline) and diesel fuels and hence can be used in existing fuel distribution systems and in standard engines. They are also known as synfuels.
BtL fuels can be produced from almost any type of low-moisture biomass: wood residues, forest thinning, bark from pulp’ n’ paper production or organic wastes such as short rotation trees, perennial grasses, straw, bagasse, waste paper or fibre-based composites.
The advantage of the BtL route to liquid transport fuels lies in the possibility to use almost any type of biomass, with little pre-treatment other than moisture control. This is because the feedstock is gasified in the first stage of the process. The gas produced is then treated further to clean it, remove tars, particulates and gaseous contaminants, and to adjust the ratio of the required gases (hydrogen and carbon monoxide) to that required. The result is a balanced syngas that can be used in the second, catalytic stage.
One of the main catalytic processes for BtL production is the Fisher-Tropsch process. The Fischer-Tropsch process is a catalyzed chemical reaction in which carbon monoxide and hydrogen are converted into liquid hydrocarbons of various forms. The FT process is an established technology and is already applied on a large scale on coal or natural gas.
Demonstration plant in Finland
At present, very little industrial scale biomass gasification takes place. One example of a demonstration project is a BtL biofuels plant owned by NSE Biofuels Oy in Varkaus, Finland. This demonstration plant was launched in summer 2009. NSE Biofuels Oy is a 50/50 joint venture between Neste Oil and Stora Enso. The facility includes a 12 MW gasifier and will be used to develop technologies and engineering solutions for a commercial-scale plant. The demonstration process units cover all stages, including the drying of biomass, gasification, gas cleaning and the testing of Fischer-Tropsch catalysts. AGA has participated in this project by supplying it with all the necessary gases.