Economic analysis and optimal design of hydrogen/diesel backup system to improve energy hubs providing the demands of sport complexes

Energy crisis has led the communities around the world to use energy hubs. These energy hubs usually consist of photovoltics, wind turbines and batteries. Diesel generators are usually used in these systems as backup system. In this research, for the first time, an attempt is made to replace the traditional diesel only backup system with hydrogen only system and combined hydrogen and diesel backup system in hybrid photovoltaic and wind turbine energy systems. After introducing the available energy modeling tools and methods, explaining over advantages and disadvantages of each one, HOMER software was selected for this research. The simulations of this research show that using the traditional diesel generator as the backup system of the energy hub, creates a low cost system with the net present cost (NPC) of 2.5 M$ but also produces the highest amount carbon emission which is equal to 686 tons/year. The results of this study also indicate the hybrid renewable energy system which is supported by the hydrogen only backup system has the highest net present cost (NPC) and initial capital cost but reduces the maximum amount of carbon. The calculated NPC and carbon production of the energy hub using hydrogen only backup system are equal to 4.39 M$ and 55,205, respectively. On the other hand, the combined hydrogen/diesel backup system has reduced NPC compared with the hydrogen only backup system. The CO₂ production of this system is also lower than the diesel only backup system. The calculations indicate that the NPC and CO₂ production of the combined backup system are 3.53 M$ and 511,695 kg/yr. By comparing advantages and disadvantages of all 3 scenarios, the micro grid which uses the combined diesel/hydrogen backup system is selected as the most optimal system. The sensitivity analysis of the selected system shows that fluctuations of inflation rate along with the fluctuations of both fuel cells and electrolyzers capital cost do not affect the net present cost (NPC) considerably. On the other hand, fluctuations of capital cost of the main components like wind turbines affect the NPC much more than the others. If the inflation rate drops from 15% to 14% and wind turbine capital cost multiplier reduces from 1 to 0.8, the NPC value will drop by the value of 300,000 $.