The pace of implementing solar thermal power plants is increasing all around the world. In many cases, solar plants are installed in arid areas with severe demand for potable water despite the large availability of seawater. Thus, the solar thermal power plant is combined with a thermal desalination unit for the cogeneration of electricity and sweat water. Iran is a country with a very strong potential for solar projects, and of course, under an intense crisis of water. Shiraz plant is one of the solar thermal power plants in operation in Iran. The plant has recently gone under an expansion project to be combined with a gas-fired boiler, aiming to double its capacity yet smoothening its power output. This study investigates the feasibility of the co-production of electricity–water in this case study based on a number of innovative methods in conventional and modified configurations. All the proposed scenarios are designed, thermodynamically modeled, and analyzed. The different configurations are compared in terms of energy efficiency and production rate. The results indicate that the combined cycle with heat supply through the condenser of the power block, as well as the heat recovery unit allocated for the gas boiler, outperforms all the other possible configurations. In this case, the average efficiency is 10.76%, and a daily freshwater production as high as 852.32 Tonne per day is possible for a 500 kW power plant.
Today, there is a continuously upgrading trend towards the use of more and more renewable energy technologies . This has even recently become a concern of the largest oil and gas exporter countries such as Iran, Qatar, and Saudi Arabia which are investing much in renewable energy systems such as solar thermal and power technologies, wind turbines, and geothermal systems . One of the most popular renewable sources is solar energy, which may come into service for heat, cold, and power supply via diferent medium technologies .
Regardless of the source of energy, there is a general agreement that among all the energy sectors, the electricity sector is of higher importance not only due to the larger spot price of electricity compared to the heat and cold but also due to the fact advanced yet large-scale electrical heat and cold suppliers are getting more cost-efective every day paving the route for dominating electricity grids among all the energy distribution systems, e.g., gas networks, district heating, and cooling . That is why renewable power production technologies have also been of much interest to the researchers and companies working in this area. This includes both solar photovoltaic and solar thermal power plants, wind farms, etc. . Evidently, solar power plants are more appropriate for locations with higher solar irradiation potential, such as arid areas. These areas, most of the time, have challenges to have access to the resources of potable water. As solar desalination techniques have reached a mature state-of-practice, it is a wise idea to make a combined solar plant for the co-production of electricity and water . This will certainly result in much better cost-efectiveness compared to the cases of either a solar electricity plant or a solar desalination plant working individually .
In this study, the Shiraz solar power plant has been analyzed as well as four diferent confgurations of the hybridization of the plant with a desalination unit for cogeneration of power and water. A MED-TVC system is considered as the desalination unit, which has been implemented in diferent confgurations to use the waste heat of the system to produce fresh water. This work investigated fve diferent scenarios: frst, the solar power plant without the desalination unit, second, using the desalination unit after the steam turbine to recover the waste heat from the turbine outlet stream, third, using both the waste heat in the condenser and exhaust gases of the boiler to generate the motive steam used in the MED-TVC unit, forth, using only the waste heat from the boiler’s exhaust gases, and ffth, recovering the turbine outlet waste heat where the power plant is solar only, and there is no auxiliary boiler.