Advanced Thermodynamic Integration in Combined Fuel and Power (CFP) Plants Producing Low Carbon Hydrogen & Power with CCUS

Demand for low carbon sources of hydrogen and power is expected to rise dramatically in the coming years as countries decarbonise their energy systems in order to meet their climate change commitments. Individually, steam methane reformers (SMR’s) and combined cycle gas power plants (CCGT’s) have the potential, when combined with carbon capture utilisation and storage (CCUS), to produce large quantities of low cost, on demand and near-zero carbon hydrogen and power respectively. As CO2 transport and storage infrastructure contributes to decarbonising industrial clusters, it is likely that both power and hydrogen will be produced in the same location, taking advantage of common infrastructure for natural gas supply, electricity grid connection and the CO2 transport and storage network. This paper builds upon previously published work in Herraiz et al, 2020 and further develops the concept of integrating the SMR and CCGT processes, via the use of flue gas sequential combustion, into a single combined fuel and power (CFP) plant. SMR equipment is installed downstream from a commercial gas turbine (GT), but upstream from the heat recovery steam generator (HRSG). Sequential combustion of the GT flue gases provides additional heat input to drive both the reforming and steam generation processes. This simultaneously reduces the overall flow rate and increases the CO2 concentration of flue gas entering the post-combustion carbon capture (PCCC) plant. This decreases the number and size of the required absorber columns, and by extension capital expenditure (CAPEX), while the thermodynamic integration inherent in the CFP plant increases the plant power or hydrogen output for a given fuel input. This paper presents the results of a newly developed, advanced integration design for a CFP plant fitted with a conventional 30 %wt. monoethanolamine (MEA) carbon capture process. This plant, when operating at full load and a 90% CO2 capture level, produces 729MW and 1800MW of low carbon power and hydrogen respectively. The process improvements detailed in this paper facilitate a 13.3% point increase in electrical efficiency over the base case and a 6.5% point increase over the previous design in Herraiz et al. A net neutral CO2 capture rate of 99.8% was found to impart a 3.5% point decrease in electrical efficiency when compared to the 90% capture case, indicating that the marginal cost increase of zero, or near-zero, emissions is viable for a CFP plant