Burning wood cleanly for electricity
The biomass gasification process involves heating biomass feedstock such as wood or coal to decompose it into solid (char), liquid and gases in a process called pyrolysis. These components can then be ‘gasified’ to produce hydrogen and other gases. When cooled, the components include solid impurities. One of the biggest obstacles to the use of biomass for power generation is the presence of tar, which condenses from the gaseous mixture as it is cooled (at its so-called dew point) and is responsible for fouling, loss of efficiency and production stoppages. The ‘SOFC fuel cell fueled by biomass gasification gas’ (GREEN-FUEL-CELL) project was undertaken to develop a reliable, up-scalable and cost-effective system to decompose tar and clean the gas produced by standard biomass gasifiers to produce high quality gas suitable for solid oxide fuel cell (SOFC) application. The researchers developed a TREC (Tar Reduction by Char) reactor employing one of the most common methods of minimising tar and capable of cleaning organic components. They carried out pyrolysis and tar reduction experiments to identify the tar dew point. Furthermore, they conducted modelling experiments to evaluate the inorganic content of the biogas, its effect on the SOFC and hot cleaning of inorganic impurities. The research team produced an integrated system consisting of a beechwood-fuelled gasifier and TREC reactor for gas cleaning connected to a SOFC stack of 30 fuel cells. They operated the system for 2 periods of 100 continuous hours with no system degradation, thus demonstrating the feasibility of producing clean gas from biomass suitable for use in a SOFC. The GREEN-FUEL-CELL project made important progress in overcoming the hurdle of tar fouling when using biomass to feed SOFCs, along the way providing data and equipment of interest to many industrial partners involved in biomass gasification. Thus, the researchers significantly enhanced the potential use of high efficiency, low emission biomass to supply Europe’s increasing electricity demand while helping it to meet ambitious goals for reduction of greenhouse gases.
