Oxyfuel power plant with co-production of DME - A bridging technology

Övrigt konferensbidrag, 2007

Capture and storage of carbon dioxide (CCS) from fossil fuelled power plants is on its way to become an important part of the pathway to a sustainable energy system, i.e. to serve as a bridging technology. Bridging technologies using fossil fuels are required in order to meet emission targets (such as corresponding to limiting the temperature increase to 2ºC in year 2100) at a cost which society seems willing to pay, considering security of supply and maintaining regional competitiveness. More specifically, current estimates and analysis yield that CCS has a large potential for reducing CO2 emissions at an avoidance cost of no more than 20 €/ton CO2 avoided. However, in order to make the bridging system flexible and minimizing lock-in effects, it is important to investigate integration possibilities between the power generation and the transportation sector and to see if CCS can help the biomass market to grow. One capture technology for which this may be possible is the so called oxyfuel process (or O2/CO2 recycle combustion process). An interesting possibility with this process would be to burn the fuel in an oxygen lean mode (i.e. slightly under stoichiometric conditions), yielding a process between combustion and gasification with co-production of synthesis gas, which can be used to synthesize different fuels or for power production. When the produced synthesis gas is used as fuel in the transportation sector the carbon present in the gas is emitted to the atmosphere. In order to compensate for these emissions a small fraction of biomass could be co-combusted in the proposed process, corresponding to the amount of carbon used for the synthesis gas production. At the same time co-combustion of biomass using a large coal power plant is an efficient way to utilize biomass. In this way the flexibility of the processes is increased and the expensive oxygen production for the oxyfuel process is minimized.