GHG reduction potential of biomass gasification pathways: An Austrian life cycle emission analysis

Dual fluidized-bed gasification of biomass is one way to defossilize the Austrian energy system. Although this technology is yet to be implemented on an industrial scale, it shows potential in terms of e.g. feedstock flexibility and product range. The present study assesses the sustainable availability of selected biomass feedstocks and quantifies the global warming potential of these feedstocks and three gasification pathways, with varying complexity. Each pathway involves the gasification of biomass to synthesis gas. The synthesis gas is either combusted to generate industrial process heat, synthesized to produce synthetic natural gas, or synthesized to Fischer Tropsch-crude and refined into sustainable aviation fuel and co-products. Furthermore, the potential for substitution of fossil fuels and the resulting reduction of greenhouse gas emissions within the Austrian energy system are assessed. The approach involves a cradle-to-gate Life Cycle Assessment, based on experimental and simulation data, derived from the 1 MW pilot gasifier Syngas Platform Vienna. The analysis indicates that the generation of industrial process heat results in the lowest greenhouse gas emissions, methanation to synthetic natural gas demonstrates the greatest potential for fossil fuel substitution, while Fischer-Tropsch synthesis shows the greatest potential for overall greenhouse gas reduction. An increase in the complexity of gasification pathways result in increased associated greenhouse gas emissions, but allows for substitution of more emission intensive fossil fuels, such as kerosene or diesel. The sustainable supply of biomass is limited; therefore, this strategic assessment determines the gasification pathway with the greatest environmental benefit per unit of biomass input.