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

Abstract

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 €/MWh (base case) show a total annualised cost of 55.6 M€/a and a levelised cost of electricity of 113.3 €/MWh. An investment analysis shows that the Graz Cycle reaches economic break-even at a natural gas price of $\sim$95 €/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.