Decarbonising the energy sector with oxy-combustion CCS: A techno-economic analysis of the Graz Cycle power plant

The objective of this paper is to assess the economic costs of an oxy-combustion power plant with CO2 capture, known as the Graz Cycle. For this purpose, we employ a methodology based on common practices in the field of point-source CO2 capture and storage (CCS) utilising a process modelling tool to analyse the economic cost metrics under (a) full-load and (b) part-load condition. On this basis, we assess (i) the total annualised cost, (ii) the levelised cost of electricity, and (iii) the CO2 avoidance cost of the Graz Cycle fired with natural gas. The result for a Graz Cycle pilot plant with approximately 62 MW net power output and a natural gas price of 30 <euro>/MWh (base case) show a total annualised cost of 55.6 M<euro>/a and a levelised cost of electricity of 113.3 <euro>/MWh. An investment analysis shows that the Graz Cycle reaches economic break-even at a natural gas price of similar to 95 <euro>/MWh. Moreover, the analysis reveals that the Graz Cycle has a cost advantage over natural gas combined cycles with post-combustion capture, particularly in scenarios with high CO2 taxes and a large installed plant capacity. The main contribution of this paper is a unique techno-economic analysis of the Graz Cycle, demonstrating its efficiency and economic viability across varying operational scenarios and CO2 tax regimes.