A Case Study of the Potential for CCS in Swedish Combined Heat and Power Plants

The global need to reduce anthropogenic CO2 emissions is imminent and might be facilitated by carbon capture and storage (CCS) technologies. Sweden has a goal to reach net-zero emissions by 2045, where negative emissions – and bio-CCS (BECCS) in particular - have been proposed as an important strategy to reach this target at the lowest cost. The Swedish district heating sector constitutes a large potential for BECCS since there is a large number of relatively large biogenic point sources of CO2 in the form of combined heat and power (CHP) plants burning biomass residues from the forest industry. This study provides a multi-level estimation of the impact and potential of CO2 capture and negative emissions in 110 existing Swedish biomass or waste-fired CHP plants, located in 78 local district heating systems. Process models of CHP steam cycles give the impact of absorption-based CCS integration on CHP plant heat and electricity production. The propagation of the plant-level impact to the unit commitment of CHP plants in district heating systems is modelled, and the potential for CO2 capture in each system is estimated. The results indicate that 45-70% of nominal steam cycle district heating generation is retained when integrating carbon capture, depending on the power-to-heat ratio; although the reduced heat output can be moderated by sacrificing electricity generation. In the district heating system context, CCS integration can lead to increased utilization and fuel use of CHP plants, in synergy with increased CO2 capture, but might also lead to greater need for peak heat and/or electricity generation. The total CO2 captured from the 45 CHP plants with modeled CO2 emissions exceeding 150 kton/year could be sufficient to meet a proposed target of 3-10 Mton/year of BECCS by Year 2045