Local infrastructures for CCS clusters: A case study of two CHP plants in Gothenburg

Abstract

Climate change is a global problem and measures to reduce CO2 emissions are required. One acknowledged measure, both in Sweden and globally, is carbon capture and storage (CCS). This thesis investigates economic benefits for infrastructure cooperation in CCS implementation including solvent regeneration, liquefaction and transport to an intermediate storage. Two combined heat and power (CHP) plants in Sävenäs owned by Renova and Göteborg Energi were investigated as a case study. The capture plants were modelled in Aspen Plus as post-combustion processes with monoethanolamine as a solvent. Heat demand and other utilities were quantified to decide the impact on the heat and electricity production at each plant. Based on the utility demand and equipment need, an economic analysis was performed. The cost for CO2 liquefaction and transport were estimated. Four scenarios for the operation of the CHP plants including maintained fuel usage, maintained district heat delivery, collaboration to maintain district heat delivery and reduced capture rate, were compared. The work concludes that, depending on scenario, the capture cost for separate plants at Renova and Göteborg Energi is 39-46 and 80-82 €/ton CO2, respectively. For a capture plant with a shared infrastructure, the capture cost is 45-52 €/ton CO2. The result shows a possible district heat recovery of 70% from the capture plant, which is important to decrease the cost of the heat demand. The heat integration with the steam cycle is important for the capture cost. Use of primary steam leads to higher variable OPEX, due to higher reductions in electricity generation, but lower impact on district heating generation, than the use of an extracted stream from the turbine. The plant utilisation is more important for the specific capture cost than the size of the CHP plant. Depending on the allocation of the cost between the companies, the possible savings are between 0.2-1.0 M€/yr corresponding to 2-5% of the total cost. Therefore, there are small economic benefits with a shared process where shared liquefaction has the most potential.