4E analysis and multi-objective optimisation for a solar hybrid steam power plant using ABC algorithm: a case study in Iran

: The objectives of this study are 4E analysis and multi-objective optimisation for solar hybrid fossil fuel power generation system and steam power plant without solar field (WSF) of Karaj during a year. The analysis is performed using MATLAB programing, and validated with a power plant unit data. The results show that system with oil-water heat exchanger (solar hybrid system), has less CO 2 emission and fuel consumption than WSF power plant but 2.8% more exergy efficiency. The annual average contribution of steam on the production of electricity during sunny hours and during the day, are 15% and 7.3%, respectively. By using artificial bee colony (ABC) algorithm, system is optimised for maximum exergy efficiency and minimum cost of produced electricity. Furthermore, sensitivity analysis is performed to study the solar tracking modes, changing the number of collector loops, capacity of the power plant, interest rate and plant economic life on unit cost. the solar-to-electricity efficiency under different turbine load for different seasons of the year. As their result, the solar-to-electricity efficiency in summer can reach up to 26.3% but, in winter, the solar-to-electricity efficiency is only 11.5% due to the increase of solar incident angle and decrease of solar irradiance. Annual thermodynamic analysis of solar hybrid fossil fuel power plant was investigated by Zhu et al. (2017). They compared performances of a solar hybrid steam power plant, a steam power plant and a solar tower power plant under different operative conditions. Parametric results showed that solar tower hybrid steam power plant has higher solar operation efficiency than solar tower power plant using natural gas back-up and lower fuel consumption flow rate and CO 2 emission flow rate than fossil fuel power plant. Thermodynamic performance and economical optimisation for a solar aided fossil fuel power generation system were performed by Wang et al. (2017). They used a solar feed water heater at < 300°C to replace the extracted steam to heat the feed water. They investigated the effects of the important operating parameters such a heat transfer fl uid (HTF) flow rate, concentration ratio and solar incident angle on the performances of the solar hybrid coal fired power generation system under different operative conditions. Results showed that levellised cost of power production of the solar hybrid power generation system 0.7–1 ¥/kwh (0.1045–0.145 $/kwh) and annual solar-to-electric efficiency 13%–20% can be achieved. Thermodynamic analysis from flue gas waste heat in a 500 MW fossil fuel power generation system using solar hybrid Kalina cycle in MS-Excel software, was modelled by Khankari and Karmakar (2018). They presented optimise power plant performance at different conditions. Their results show that net power generation 516.52 kWh can be