Towards sustainable energy Carriers: A solar and Wind-Based systems for green liquid hydrogen and ammonia production

Power-to-fuel energy systems have an essential need for decarbonizing energy carriers. This study proposes a solar and wind energy-based system for producing liquid hydrogen and ammonia as energy carriers. The proposed system caters to urban requirements encompassing electricity, cooling, heating, and freshwater. Three different scenarios, only liquid hydrogen, only ammonia, and dual production, are considered and compared. An artificial neural network is employed for prediction and computational time reduction, coupled with a genetic algorithm for system optimization. For a case in which 40 % of the net power is used in the electrolyzer, and the system simultaneously produces liquid hydrogen and ammonia, the overall energy and exergy performance of the system are 56.78 % and 44.69 %, respectively. In this case, the system has the capability of producing 13.2 MW of net power, 0.057 kg/s of liquid hydrogen, 0.162 kg/s of cold ammonia, 3.63 kg/s of freshwater, and 3.4 MW cooling load. The exergy analysis of the system reveals that the Rankine cycle and the electrolyzer have the highest exergy destruction, at 27 % and 21 %, respectively. Using the Technique for Order Preference by Similarity to Ideal Solution method, the optimal liquid hydrogen rate, ammonia production rate, overall exergy efficiency, and net power are determined as 0.026 kg/s, 0.151 kg/s, 51.38 %, and 16.52 MW respectively are recognized as optimal values for dual production scenario.