Environmental analysis of bio-CCS in an integrated oxy-fuel combustion power plant with CO2 transport and storage

Oxy-fuel combustion (OFC) belongs to one of the three commonly known clean coal technologies for which practical application may be in the offing. Similarly to conventional power plants, there is a possibility of biomass co-firing, thus an additional reduction of CO₂ emission is possible. Including the biomass in the fuel mixture of an integrated OFC power plant allows to obtain the so called “neutral” CO₂ status as biomass combustion does not contribute to anthropogenic CO₂ emissions. In OFC power plants without biomass co-firing, even if 100% of CO₂ is captured, there are still additional CO₂ emissions in processes like fossil fuel extraction, transportation and preparation. The same assumption applies also to biomass and other materials (e.g. limestone or raw water). A higher share of biomass in the fuel mixture can lead to “negative” CO₂ emissions with may be helpful to compensate the unfulfilled goals in other sectors where reduction is required. The paper presents the system approach to the environmental analysis based on the “input–output” method and both the index of the thermoecological cost and cumulative CO₂ emissions. Thermoecological cost includes, the cumulative exergy consumption of non-renewable energy sources and additional exergy consumption due to harmful emissions to the atmosphere. In order to investigate the impact of bio-CCS (both biomass co-firing and dedicated biomass boilers) on the net thermoecological cost of electricity production and cumulative CO₂ emissions five cases have been analyzed.