I. Working Principle of Fuel Cell Vehicles
The working principle of a fuel cell vehicle is that hydrogen, as fuel, undergoes an oxidation-reduction chemical reaction with oxygen in the atmosphere in the fuel cell installed in the vehicle, generating electrical energy to drive the electric motor. The electric motor drives the mechanical transmission structure in the vehicle, which in turn drives the vehicle's front (or rear) axle and other walking mechanical structures, thus propelling the electric vehicle forward.
Fuel cell reactions produce very little carbon dioxide and nitrogen oxides, with water being the main byproduct, hence the term "green" or "environmentally friendly" vehicles. Fuel cell vehicles are a type of electric vehicle, with the fuel cell as their core component. They convert hydrogen and oxygen directly into electrical energy through the chemical reaction of hydrogen and oxygen, rather than through combustion.
Hydrogen fuel for fuel cell vehicles can be obtained through several methods. Some vehicles carry pure hydrogen fuel directly, while others may be equipped with a fuel reformer that converts hydrocarbon fuels into hydrogen-rich gas. Individual fuel cells must be combined into fuel cell stacks to obtain the necessary power to meet the vehicle's operating requirements.
II. Advantages of Fuel Cell Electric Vehicles
1. Near-zero emissions: Fuel cells use hydrogen and oxygen as fuel, and the byproduct is clean water. They do not produce CO or CO2 during operation, nor do they emit sulfur or particulates. There are no high-temperature reactions, and no NOx is produced. If an onboard methanol reforming catalytic converter is used to supply hydrogen, only trace amounts of CO and a small amount of CO2 will be produced.
2. High energy conversion efficiency: The energy conversion efficiency of fuel cells can reach 60% to 80%, which is 2 to 3 times that of internal combustion engines.
3. Long lifespan: Fuel cells operate without noise, movement, or vibration. Their electrodes serve only as sites for chemical reactions and conductive channels, without participating in chemical reactions themselves. Therefore, they experience no wear and tear and have a long lifespan.
4. Wide range of fuel sources: Hydrogen fuel has a wide range of sources and can be obtained from renewable energy sources, without relying on petroleum fuels.
Fuel cells come in many types and can generally be classified according to their operating temperature, fuel type, and electrolyte type. Based on operating temperature, fuel cells can be divided into high-, medium-, and low-temperature types. Low-temperature fuel cells operate from room temperature to 100°C; medium-temperature fuel cells operate from 100°C to 300°C; and high-temperature fuel cells operate above 500°C. Based on fuel source, fuel cells can be divided into two categories: direct fuel cells, which use hydrogen directly as fuel; and indirect fuel cells, which use hydrogen (H2), methane (CH4), methanol (CH3OH), or other hydrocarbon compounds converted into hydrogen or hydrogen-rich mixtures to supply the fuel cell. Based on electrolyte, fuel cells can be broadly classified into five types: ① Alkaline fuel cells (AFC); ② Phosphoric acid fuel cells (PAFC); ③ Solid oxide fuel cells (SOFC); ④ Molten carbonate fuel cells (MCFC); and ⑤ Proton exchange membrane fuel cells (PEMFC).
III. Disadvantages of Fuel Cell Electric Vehicles
Currently, the overall energy conversion efficiency of most hydrogen fuel cells is far lower than that of pure electric vehicles. If it is a renewable method, the efficiency is generally lower than that of power generation, which is a waste of energy compared to pure electric vehicles and increases operating costs. If it is generated from fossil fuels, even if it is a byproduct, it is still a byproduct of a polluting production process. If it is generated from electricity, it adds an extra step that causes energy loss. In summary, in terms of energy consumption for driving alone, it may not be as economical and environmentally friendly as pure electric or plug-in hybrid vehicles.
Hydrogen fuel cell technology is not mature enough.
The high cost and lack of hydrogen refueling infrastructure, coupled with the chicken-and-egg dilemma similar to the development of charging stations, presents significant challenges. Unlike the early stages of electric vehicle charging, which could leverage home charging infrastructure and gradually expand to public charging stations and large-scale fast-charging stations, hydrogen refueling requires a direct shift to large-scale hydrogen refueling stations. This significant early infrastructure development hurdle hinders the expansion of fuel cell vehicle sales, which is the biggest obstacle. Furthermore, refueling fuel cells with fuel intended for power generation remains a problem.
