Thermodynamic and Economic Analysis of an Integrated Solar Combined Cycle System
Integrating solar thermal energy into the conventional Combined Cycle Power Plant (CCPP) has been proved to be an efficient way to use solar energy and improve the generation efficiency of CCPP. In this paper, the energy, exergy, and economic (3E) methods were applied to the models of the Integrated Solar Combined Cycle System (ISCCS). The performances of the proposed system were not only assessed by energy and exergy efficiency, as well as exergy destruction, but also through varied thermodynamic parameters such as DNI and Ta. Besides, to better understand the real potentials for improving the components, exergy destruction was split into endogenous/exogenous and avoidable/unavoidable parts. Results indicate that the combustion chamber of the gas turbine has the largest endogenous and unavoidable exergy destruction values of 202.23 MW and 197.63 MW, and the values of the parabolic trough solar collector are 51.77 MW and 50.01 MW. For the overall power plant, the exogenous and avoidable exergy destruction rates resulted in 17.61% and 17.78%, respectively. In addition, the proposed system can save a fuel cost of 1.86 $/MW·h per year accompanied by reducing CO2 emissions of about 88.40 kg/MW·h, further highlighting the great potential of ISCCS.
Optimal design and operation of integrated solar combined cycles under emissions intensity constraints
Abstract Direct integration of solar thermal and natural gas systems can be achieved through integrated solar combined cycle (ISCC) power generation. In this work, optimal ISCC system design and hourly operations are determined simultaneously using computational optimization procedures. The full optimization problem is intractable, so a series of problem reductions are employed to explore the ISCC design space while ensuring that individual designs can operate feasibly for a wide range of operating conditions and under realistic constraints. We construct bi-objective Pareto fronts for two conflicting objectives: net present value (NPV) and average CO2 emissions intensity of power produced. A variety of ISCC designs are explored to find a superior configuration with physically feasible annual solar contribution (ASC) of up to 20%, a significant improvement over published designs. We then explore the sensitivity of the results to economic factors such as discount rate, power price, and capital cost. By examining the Pareto frontiers of each case, we quantify the economic cost of reduced CO2 emissions. The resulting ISCC-derived mitigation costs are found to be competitive with other CO2 mitigation technologies.
Techno-economic analysis of chemical looping combustion with humid air turbine power cycle
Abstract Power generation from fossil fuel-fired power plant is the largest single source of CO2 emission. CO2 emission contributes to climate change. On the other hand, renewable energy is hindered by complex constraints in dealing with large scale application and high price. Power generation from fossil fuels with CO2 capture is therefore necessary to meet the increasing energy demand, and reduce the emission of CO2. This paper presents a process simulation and economic analysis of the chemical looping combustion (CLC) integrated with humid air turbine (HAT) cycle for natural gas-fired power plant with CO2 capture. The study shows that the CLC–HAT including CO2 capture has a thermal efficiency of 57% at oxidizing temperature of 1200 °C and reducer inlet temperature of 530 °C. The economic evaluation shows that the 50 MWth plant with a projected lifetime of 30 years will have a payback period of 7 years and 6 years for conventional HAT and CLC–HAT cycles respectively. The analysis indicates that CLC–HAT process has a high potential to be commercialised.