Thermo-environmental analysis of a renewable Allam Cycle for generating higher power and less CO2 emissions

Although CO2 emissions from burning fossil fuels have caused numerous environmental problems, the utilization of oxy-fuel cycles has proven to be an effective method for generating more power while minimizing CO2 emissions. In this study, an innovative power generation system was presented that integrates renewable energies (solar and wind) with a small-scale oxy-fuel cycle (Allam Cycle). The system underwent modeling, simulation, and optimization from energy, exergy, exergoeconomic, and environmental perspectives. Generating higher power and emitting lower CO2 emissions compared to conventional gas turbines was the main goal of this study. Additionally, to present results meaningfully, comparisons were made between two different weather conditions: St. Petersburg in Russia (cold climate) and Tehran in Iran (normal climate). In this regard, dynamic analysis was performed using TRNSYS and Engineering Equation Solver (EES) tools. Furthermore, a multi-objective optimization was conducted using the TOPSIS multi-criteria method on functional parameters. The optimization results revealed that the maximum energy efficiency and minimum total cost rate were achieved at 75 % for Tehran and 1.84 $/h for St. Petersburg. Providing power for internal components, the highest power sold to the grid was reported to be 8365 kWh in December in St. Petersburg and 9646 kWh in May in Tehran. Additionally, the flat plate collector (FPC) demonstrated maximum efficiency and stored heat of 36 % in Tehran and 2.25 kWh in St. Petersburg, respectively. Ultimately, the results of pollutant emissions indicated that the Allam Cycle achieved a significant CO2 reduction compared to a conventional gas turbine, with a reduction ratio of 117 times in St. Petersburg and 119 times in Tehran.