Is Blue Hydrogen a Better Alternative Than Post-Combustion Carbon Capture for Combined Cycle Gas Turbines? A Thermodynamic Point of View

Abstract
Today, the impact of global warming is more tangible than ever and every sector of society needs to engage in a low-carbon plan of action. For the last few years, increasing the share of variable renewable energy (VRE) has been the strategy of the energy sector to cut CO2 emissions. It requires the energy system to enhance its flexibility, voltage and frequency control, and firm capacity. To maintain the desired stability, combined cycle gas turbine (CCGT) plants come as the ideal candidates. However, if natural gas (NG) remains the primary fuel, the gas turbines (GT) will not comply with carbon emission limits in the future. Decarbonization must, therefore, be implemented in CCGTs. Original equipment manufacturers (OEM) are turning toward hydrogen-fueled GTs. Nevertheless, the production of H2 remains a challenge. In the long run, with a surplus of renewables and the development of more powerful electrolyzers, green or zero-carbon hydrogen could be achievable on a large scale. For the moment, the most mature low-carbon method is steam methane reforming (SMR) combined with carbon capture (CC), producing the so-called blue-H2. Alternatively, post-combustion CC presents another low-carbon solution for CCGTs. However, there is quite some debate is in the literature on the most effective pathway toward CCGT decarbonization. Using multiple Aspen Plus models of an HA-class GT combined with a three-level pressure heat recovery steam generator (HRSG), a CC unit, and an SMR process, the study presented in this paper seeks to assess the performance of both solutions. Simulation results show that for the blue-H2 scenario, the production of blue-H2 has an energy penalty of 24% on the CCGT. On the other hand, post-combustion CC implies an energy penalty of 10%, making the CC-only case the most efficient pathway under the studied conditions.