Integration Aspects of Biomass Gasification in Large Industrial or Regional Energy Systems – Consequences for Greenhouse Gas Emissions and Economic Performance
The objective of this thesis is to identify and evaluate important parameters for future largescale solid biomass gasification systems and their integration with existing industry and infrastructure to reduce the GHG emissions and to improve the economic performance of these systems compared to stand-alone configurations.
Biomass gasification has been pointed out as a technology with significant potential to produce motor fuels with low greenhouse gas (GHG) emissions from a life cycle perspective. In addition, other chemicals can also be produced by this technology but so far biofuel and chemical production by this route is still under development and not commercially implemented. This thesis identifies and evaluates important parameters for future large-scale solid biomass gasification systems and their integration with existing industry and infrastructure to reduce the GHG emissions and to improve the economic performance of these systems compared to stand-alone configurations. Three development routes, each consisting of one gasification-based biofuel production system and a specific case study location with integration potential with a district heating system or nearby industry are analysed. The included biofuels are: SNG (synthetic natural gas), methanol and Fischer-Tropsch fuels.
The considered integration options are; heat integration or integration of material streams, such as CO2 for storage, and co-utilisation of process equipment. The feedstock used in the systems is forest residues and different raw material supply chains and pretreatments were analysed. Future energy market scenarios that correspond to a wide range of possible future energy and fuel prices under different climate policy scenarios are used in the evaluation. For the investigated cases and energy market scenarios, heat integrating the gasification-based systems with industry show robust GHG emissions reductions and increases in profitability. On the other hand, the results of integration with district heating systems varies depending on the replaced heat production technology and energy market scenario.
The results also show that connecting the biofuel production system to future infrastructure of CO2 storage significantly improves the GHG emission reduction potential and can also contribute to important cost-reductions in scenarios with strong climate policies. The analysis of raw material supply chains showed that the GHG emissions are lower for the systems with onsite biomass drying. Systems using pellets transported by ship and dried by other excess heat could result in just slightly increased emissions. Only some of the analysed SNG cases and one of the Fischer-Tropsch cases showed profitability for some of the investigated scenarios and economic assumptions.