Solar fuel production by developing an integrated biodiesel production process and solar thermal energy system

To diminish the consumption of fossil fuels and their subsequent pollutions, biodiesel plays an important role in the transportation section. Biodiesel production processes can be coupled with renewable energy sources to achieve higher energy efficiency and higher renewability. Also, employing a sub-system to produce power simultaneously increases the process performance as well. In the present study, a new integrated cogeneration process for the production of biodiesel and power using solar energy is proposed and analyzed. Methanol, fresh oil, and sodium hydroxide, at 25 degrees C and 100 kPa, enter into the biodiesel production unit as feed. Yazd city in Iran, located between 31.88 N and 54.28 E, is considered as base region for simulating the parabolic trough solar collector. To design a cogeneration plant, the organic Rankine cycle is combined with the solar system to supply the required process power. The proposed system produces 991.42 kg/h of biodiesel with a yield of 94.42% and 1718 kW net power simultaneously. The total energy efficiency is 60.83%, showing the capability of the proposed process for biodiesel and power cogeneration from renewability and environmental perspective. Also, the exergy analysis applied to evaluate the proposed plants thermodynamic performance. The total exergy efficiency of the system is 74.38% when the highest exergy destruction rate takes place inside the parabolic trough solar collectors.