# Portable Prototype of Hydrogen Fuel Cells for Educational Training
## 2 Theoretical Background
### Applications of Fuel Cells  
Integrating fuel cells into automobiles may transform the automotive industry since hydrogen energy is renewable. The reactants of fuel cells are oxygen and hydrogen, with water as a byproduct. Almost a decade ago, hydrogen and electricity were positioned as the greatest conceivable replacements for traditional fossil-fuel automobiles. Nonetheless, battery-powered electric vehicles continue to dominate the transition to our envisioned environmentally friendly transportation system. However, historical data patterns reveal that hydrogen-powered cars have yet to ramp up the pace of integration into our transportation system. Electric vehicles, on the other hand, outsell hydrogen-powered vehicles owing to the considerable hydrogen infrastructure needed, which is still lacking when compared to electric vehicle charging stations [25,26].  
The main component of fuel cell vehicles is the fuel cell itself, motor, battery, coolant, and air cleaning system, as shown in Figure 1. Fuel cells produce electricity to power the electric vehicle's motor by converting hydrogen. The charging time of electric cars is a significant problem that can take even hours, but in the case of fuel cell vehicles, the tank can be refilled within minutes, just like conventional vehicles. Moreover, in terms of mileage, fuel cell vehicles outperform electric vehicles [27].  
[PERSON] et al. [28] simulated vehicle proton exchange membrane FC application. This simulation model examined FC fuel economy in automotive applications and control strategies. Controlling the air compressor, cooling system, and other auto parts could boost PEMFC efficiency. Two cases were studied. The first case had perfect air compressor control, while the second had none. Because vehicle load changes with speed, this simulation examined power train performance under various load cycles. [PERSON] et al. [29] discussed FC vehicle fuel economy. FC vehicles had 2.7 times the fuel economy of conventional vehicles. FCV fuel economy competed with IC engine vehicles even at 0.6 V, the theoretical cell voltage of 0.7 V. FC efficiency and low driving load profiles drove this fuel economy. The parasitic losses are minimized in the FC. In non-hybrid vehicles, FC voltage below 0.6 V reduces fuel economy. FC vehicles need the air management system because it has the highest parasitic losses. The air management system should provide reasonable turndown and operate at low pressures.  
Other uses of hydrogen FC can be found in both the residential and commercial sectors. The residential and commercial sectors contribute 30% of greenhouse gas emissions globally, which can be reduced by replacing the conventional system with an FC grid-connected CHP system. A 1 kW FC system can help to reduce the 1250 Kg CO2 emissions per household. It was found that the energy supply from FC production units to the residential sector will be more cost-effective than the local grid supply due to the low operational cost of the fuel cell [30]. Research is now focusing on integrating FC into CHP and cogeneration units to generate electricity for the residential and commercial sectors. As hydrogen is produced from water and 70% of the earth is covered in water, the potential of hydrogen energy is immense. SOFC can operate at high temperatures, even at 800 \({}^{\circ}\)C, so it is most suitable for application in cogenerations power units and CHP [31].