What are fuel cell vehicles? Fuel cell vehicle classification. Advantages and disadvantages of fuel cell vehicles.

4. Advantages of Fuel Cell Electric Vehicles

Compared with traditional cars and pure electric vehicle technology, fuel cell electric vehicles have the following advantages.

① Zero emission or near zero emission, green and environmentally friendly. Fuel cell electric vehicles are essentially zero emission vehicles. Fuel cells do not have a combustion process. If pure hydrogen is used as fuel, hydrogen and oxygen are combined through electrochemical methods, and the product is clean water; other hydrogen-rich organic compounds are used to produce hydrogen with an on-board reformer as fuel for fuel cells. In addition to water, the product may also contain a small amount of C02, but its emissions are much less than those of internal combustion engines, and there are no other pollution emissions (such as nitrogen oxides, sulfur oxides, hydrocarbons or particulates), close to zero emissions. Compared with traditional vehicles, it not only reduces water pollution caused by oil leakage, but also reduces greenhouse gas emissions.

② High energy conversion efficiency, energy saving. The energy conversion efficiency of fuel cells is extremely high. Fuel cells do not have mechanical parts such as pistons or turbines, nor do they undergo a thermal engine process or are not restricted by a thermodynamic cycle (Carnot cycle). Therefore, the energy conversion efficiency is high. The chemical energy conversion efficiency of fuel cells can theoretically reach 100%, and the actual efficiency has reached 60% to 80%, which is 2 to 3 times the thermal efficiency of ordinary internal combustion engines (the vehicle efficiency of gasoline and diesel engines is 16%-18% and 22% to 24% respectively). Therefore, from the perspective of energy conservation, fuel cell vehicles are significantly better than ordinary vehicles using internal combustion engines.

③ Fuel diversification optimizes the energy consumption structure. The hydrogen fuel used by fuel cells has a wide range of sources. In nature, hydrogen energy is stored in water in large quantities. It can be produced by water decomposition or obtained from renewable energy sources, such as natural gas, propane, methanol, gasoline, diesel, coal, and renewable energy. The diversification of fuel sources is conducive to energy supply security and the use of existing transportation infrastructure (such as gas stations, etc.). Fuel cells do not rely on petroleum fuels. Various renewable energy sources can be converted into hydrogen energy for effective use, reducing dependence on petroleum resources and optimizing the composition of transportation energy.

④ Long driving range and better performance than other battery electric vehicles. The use of fuel cell power generation system as an energy source overcomes the shortcomings of short driving range of pure electric vehicles. Its long-distance driving ability and power are close to those of traditional vehicles. Fuel cell vehicles can generate electricity on board, and as long as we bring enough fuel, it can take us anywhere we want to go. Fuel cell electric vehicles are significantly better than other battery electric vehicles in terms of cost and overall performance (especially in terms of range and refueling time).

⑤ Strong overload capacity. In addition to having high working efficiency in a wide working range, the fuel cell has a short-term overload capacity of up to 200% of the rated power or more, which is more suitable for automobile acceleration, climbing and other working conditions. The short-term overload capacity of the fuel cell can reach 200% of the rated power.

⑥ Smooth operation and low noise. Fuel cells are static energy conversion devices with no moving parts except the air compressor and cooling system. Therefore, compared with internal combustion engine vehicles, they are free from the roar of the motor and have less noise and vibration during operation.

5. Disadvantages of Fuel Cell Electric Vehicles

① The manufacturing and use costs of fuel cell vehicles are too high. One of the biggest factors restricting the promotion and application of fuel cell vehicles is that the production cost of fuel cells has remained high. How to reduce the production cost of fuel cells has become the key to the practical application of fuel cell vehicles. According to the US Department of Energy, the current production cost of fuel cells has dropped to $500/kN. Experts estimate that only when the production cost of fuel cells drops to $50/kW can they be accepted by consumers. In other words, when the cost of a 80kW automotive fuel cell drops to the current price of $3,500 for a gasoline engine, it will create huge market benefits. From the perspective of market economics, it is difficult to achieve market promotion at high costs, and if marketization cannot be achieved, large-scale mass production is impossible, and then the cost cannot be reduced, which ultimately leads to a vicious cycle of cost and sales.

On the other hand, the cost of using fuel cell vehicles is too high. The price of hydrogen is not cheap, so the operating cost of fuel cell vehicles is not optimistic. At present, the cost of providing 1 kilowatt-hour of electricity by a fuel cell power generation system is much higher than that of various power batteries. This reflects from one aspect that fuel cells are still a long way to go as a power source for automobiles.

② The startup time is long, and the system's anti-vibration ability needs to be improved. The startup time of FCEVs using hydrogen as fuel generally takes more than 3 minutes, while FCEVs using methanol or gasoline reforming technology take up to 10 minutes, which is much longer than the startup time of internal combustion engine vehicles, affecting their maneuverability. In addition, when FCEVs are subjected to vibration or impact, the reliability of the connection and sealing of various pipelines needs to be further improved to prevent leakage, reduce efficiency, and cause safety accidents in serious cases.

③ There are still technical difficulties in obtaining pure hydrogen fuel economically and without pollution. Converting traditional fossil fuels to obtain pure hydrogen natural gas through reforming or modification technology not only consumes a lot of energy, but also does not fundamentally get rid of dependence on fossil energy, nor does it fundamentally eliminate pollution to the environment. In nature, hydrogen energy is stored in large quantities in water. Although it is inexhaustible, it is obviously not cost-effective to directly use thermal decomposition or electrolysis to produce hydrogen from water. Therefore, most scientists have turned their attention to the use of solar energy, but there are still many technical obstacles. At present, they are conducting research on solar water decomposition to produce hydrogen, solar power generation and electrolysis of water to produce hydrogen, sunlight catalytic photolysis of water to produce hydrogen, and solar biohydrogen production. Only when hydrogen fuel can be produced cheaply with renewable energy, the fuel problem of hydrogen fuel cell civilian vehicles can be fundamentally solved.

④ There are still a lot of technical problems to be solved in the supply of hydrogen fuel cell vehicle fuel. Hydrogen can usually be stored and transported in three states: high-pressure gas, liquid and hydride. Hydrogen stored in commonly used compressed gas tanks can only supply fuel cell vehicles with a driving range of 150km. The driving range is too short and is not as good as battery-driven vehicles. Since hydrogen is the smallest molecule, it is easy to leak. Even a small amount of leakage may cause extremely terrible consequences. The deep refrigeration technology for storing liquid hydrogen at -253℃ is still very immature. Globally, there are currently few hydrogen refueling stations that can refuel liquid hydrogen. Fortunately, the development of hydrogen storage materials has made some progress.

⑤ The auxiliary equipment for supplying fuel is complex, and its mass and volume are large. In FCEVs fueled by methanol or gasoline, the "crude hydrogen" coming out of the reformer contains a small amount of harmful gases that "poison" the catalyst and make it ineffective. It must be treated with corresponding purification devices, which increases the complexity of the structure and process and makes the system bulky. Currently, FCEVs that generally use hydrogen fuel require special storage tanks with high pressure, low temperature and protection, which leads to large volume and brings many inconveniences to the use of FCEVs.

⑥ The large-scale application of rare metal platinum Pt also restricts the promotion and application of fuel cell electric vehicles. Rare metal platinum is an indispensable reaction catalyst for fuel cells. According to the consumption of platinum by existing fuel cells, if all the platinum reserves on the earth are used to make automotive fuel cells, it can only meet the needs of several million vehicles.

⑦ The construction of basic network facilities such as hydrogen refueling stations is almost zero. Currently, there are only more than 100 hydrogen refueling stations in use worldwide, and most of them are used for experimental purposes. If technology and cost are problems that scientific research institutions and enterprises can solve by themselves through hard work, then the construction of corresponding supporting facilities cannot be completed by one person alone. It requires preparations in many aspects such as national policies, industrial chains, and infrastructure construction, and timely formulation of complete industry standards and norms for the construction of infrastructure such as hydrogen refueling stations. It involves not only urban planning, transportation, electricity and other issues, but also solves the profit problems of investors and operators, and effectively solves the core technology and unified standards of hydrogen refueling. For buses with a certain driving range, this problem may be easy to solve, but for private cars, it is a long way to go to solve these problems.