Exergoeconomic analysis of hybrid sCO2 Brayton power cycle

A hybrid power cycle is designed based on the Allam cycle configuration. The system utilizes solar power as its primary heat source and natural gas oxy-combustion as a complementing heat source. The purpose of the complimenting heat source is continual production when the sun is not available and to ensure the reliability, responsiveness, and availability of the cycle for power generation with minimal adverse effects on the environment. This study is divided into three major steps. The first and second are energy and exergy analyses. The third step is exergoeconomic analysis to obtain the cost contribution of cycle components relative to its final product. Both configurations brought similar power output and second law efficiency. However, the energy efficiency was higher for the oxy-combustion configuration. The total product cost ($/GJ) for the oxy-combustion configuration was 50% less for the concentrated solar power configuration. The unit cost of electricity in (Cent/kWh) for the concentrated solar power configuration is approximately 60% higher than for the oxy-combustion configuration. The results showed potential reduction and cost-saving for both configurations; reducing exergy destruction in the main heat exchanger and the recuperator (concentrated solar power) or replacing the air separation unit (oxy-combustion configuration). •Design of novel hybrid power cycle with two different heat sources: oxy-combustion and concentrated solar power.•The sCO2 power cycle has similar power output and exergy efficiency for both heat sources.•The PHX and the recuperator have significant effect on the overall cost of the CSP heat source.•The combustor and ASU are the most critical components to reduce the cost of the Oxy-combustion heat source.•Higher the turbine inlet temperature and pressure improve thermodynamic and exergoeconomic performance.