Thermo-economic optimization of a hybrid solar-wind energy system for the production of clean hydrogen and electricity

Abstract

With the increasing warming of the atmosphere and the growth of energy consumption in the world, new methods and highly efficient energy systems take precedence over conventional methods. This study concentrates on the proposition and techno-economical investigation of a hybrid wind-solar energy system encompassing flat plate solar collector for the purpose of clean hydrogen and electricity generation. The proposed system is a combination of flat plate solar collectors, wind turbine, organic Rankine cycle, and proton exchange membrane electrolyser. Wind speed, turbine inlet temperature, incident solar irradiation, and collector-related parameters including its surface area and fluid mass flow rate are selected decision variables, the impacts of which on the exergy efficiency and exergy loss of the scheme are examined. The objective functions included total cost rate and total exergy efficiency. The Nelder-Mead optimization method and EES software were utilized to achieve the mentioned goals, followed by a comparative case study was conducted for two cities with high potential in Iran. According to the optimization results, the exergy efficiency of 13.35 % was achieved while the cost rate was equal to $25.48 per hour, respectively. According to the sensitivity analysis, the increment in the solar collector area, incident solar irradiation, wind speed, and turbine inlet temperature improved the system's technical performance. Furthermore, the exergy loss analysis pointed out that the increment in the turbine inlet temperature, not only improves the system's performance, but also reduces the exergy loss. A comparison of the electricity production in Semnan and Isfahan showed that 1192613.4 and 1188897.6 of electricity were produced in the two cities in one year, respectively. The city of Semnan with the production of 2762.86 kg/h of hydrogen presented better system performance compared to the city of Isfahan with 2757.004 kg/h of hydrogen.