A Comparison of Low-carbon Gas-turbine Power Generation Cycles

This study investigates potential solutions for low-carbon power generation with hydrogen firing and carbon capture. Multi-dimensional system modeling was used to assess the effects on plant performance, size, and cost. The examined cycles include advanced dry-, wet-, bottoming-, oxyfuel cycles with air-separation units, and post-combustion carbon capture with exhaust gas recirculation. The results identify three distinct lowcarbon technology pathways. While conventional combined-cycle plants are suitable for hydrogen retrofits, hydrogen firing (both blue and green) results in levelized costs of electricity 50%–300% higher than carbon capture solutions, making carbon capture more attractive for long-term energy storage. When carbon capture is applied to conventional combined cycles, they become suboptimal compared to alternative solutions. The intercooled-recuperated (ICR) gas turbine cycle integrated with post-combustion carbon capture offers superior performance: over 3% higher efficiency, 12% lower capital costs, and 70% smaller physical footprint compared to conventional combined cycles with carbon capture. The Allam cycle represents a third pathway, achieving 100% CO2 capture with efficiency comparable to combined cycles at 90% capture. Gas separation units emerge as the dominant source of both capital costs and efficiency penalties across all carbon capture configurations, representing the key area for future optimization to reduce overall electricity costs.