New Opportunities and System Consequences for Biomass Integrated Gasification Technology in CHP Applications

Doctoral thesis, 2005

There are currently many driving forces for increasing electricity production in biomass CHP plants. This thesis presents techno-economic and CO2 emissions analyses for biomass integrated gasification technology in CHP applications. The aim is to examine the future role of this technology with focus on: (i) technical performance including performance variation at part load and identification of minimum acceptable load for different process configurations and fuel options; (ii) economic analysis accounting for constraints imposed by the characteristics of the host energy system; and (iii) possible innovative implementation opportunities for the technology such as simultaneous heat delivery to an industrial process and a district heating system, and retrofit of natural gas combined cycle CHP units for co-firing with gasified biofuel. The main question the thesis aims to investigate is under which future conditions it can be economically attractive to invest in biomass integrated gasification technology for CHP applications. The main performance indicator considered is the cost of electricity (COE). CO2 emissions consequences are also discussed. Different scenarios for future energy market parameters are considered, including fuel prices, reference electric power production technologies and generation costs, and costs associated with energy and climate-change policy instruments. The results indicate that BIGCC CHP technology could play an important role in future energy systems. One major advantage of this technology is that it produces significantly more electricity than conventional biomass steam turbine CHP technology, for a given heat load. Energy market conditions, and particularly costs associated with policy instruments, are shown to play a decisive role for the profitability of the technology. A key finding of the thesis is that for a variety of possible future energy market scenarios including market-oriented policy instruments such as trading with CO2 emissions allowances, a high value for CO2 emissions allowances is insufficient to make BIGCC technology profitable compared to NGCC CHP. Additional policy instruments that specifically support renewable fuels such as biomass are necessary, for example the Swedish renewable energy certificate system.