What is a fuel cell?
A fuel cell is a chemical device that directly converts the chemical energy possessed by a fuel into electrical energy. It is also called an electrochemical generator, which is mainly composed of an electrode, an electrolyte separator, and a current collector. It is the fourth generation technology after hydroelectric, thermal and atomic power generation. From the perspective of energy conservation and ecological protection, fuel cells are the most promising power generation technology.
Fuel cell power generation principle
A fuel cell is an energy conversion device that directly converts chemical energy stored in a fuel and an oxidant into electrical energy according to an electrochemical principle, that is, a working principle of a primary battery, so that the process is actually a redox reaction. During operation, the hydrogen supplied to the external battery emits electrons at the fuel electrode to become hydrogen ions. The hydrogen ions pass through the electrolyte and then turn to the air electrode, and the electrons pass through the external circuit to reach the air electrode. At the air electrode, the oxygen supplied to the battery from the outside reacts with hydrogen ions and electrons to form water. The electrical energy is output by an external circuit. Fuel cells and ordinary dry cells are devices that convert chemical energy into electrical energy, but there is a big difference between them. The substances that are involved in the chemical reaction in the dry battery will eventually be exhausted and the reaction will stop. The electrical energy is output; but for the fuel cell, as long as it is continuously supplied with fuel gas and oxidant, the chemical reaction can continue until the electric energy is continuously output.
Fuel cell advantage
1. Less pollution to the environment
The reason why fuel cells are considered to be the ultimate choice for new energy vehicles in the future is that fuel cells have little environmental pollution. A fuel cell electric vehicle is essentially a zero-emission vehicle. The fuel cell has no combustion process. If pure hydrogen is used as a fuel, the combination of hydrogen and oxygen by electrochemical means only produces water. Hydrogen production from other hydrogen-rich organic compounds using a vehicle-mounted reformer as a fuel cell fuel, the product may have a small amount of carbon dioxide in addition to water, but its emissions are much less than the internal combustion engine, and there is no other pollution emissions, such as nitrogen oxides. , sulfur oxides, etc., close to zero emissions. Compared with the traditional car, the pollution caused by the oil leakage is reduced, and the greenhouse gas emission is reduced, so the pollution of the fuel cell stack environment is small.
2. High energy conversion rate
The fuel cell does not have mechanical parts and intermediate links such as pistons or turbines, so it is not limited by the Carnot cycle. It converts chemical energy directly into electric energy during operation, so it does not generate a large amount of exhaust gas and waste heat compared to the combustion of the internal combustion engine. The energy conversion efficiency can currently reach about 40% to 60%, while the conversion efficiency of an internal combustion engine is only about 10 to 20%. High energy conversion rates can save a lot of energy.
3. Wide range of fuels available
Fuel cells can be used in a wide range of fuels, and energy sources containing hydrogen atoms can be used as fuel for fuel cells. Hydrogen can be obtained by water decomposition or by other renewable energy sources such as natural gas, propane, coal, biogas, methanol, and the like. A wide range of fuels can be used, and energy diversity is strong, which can reduce dependence on existing major energy oil, optimize energy structure, and alleviate energy shortages.
4. Relatively high security
During the operation of the fuel cell, the battery temperature will not exceed 100 ° C. If the cooling measures are added, the temperature will be lower. In addition, if the outer casing of the fuel cell is broken, there will be no explosion, only combustion reaction, compared with other batteries. It is safer.
5. Strong stability
Whether the fuel cell operates above its rated power or below its rated power, it can withstand stability and has little change in efficiency. In addition, it can also reach 200% of rated power in a short-term overload capacity and still operate stably, which is very suitable for acceleration and climbing of automobiles.
6. Low noise during operation
The structure of the fuel cell is very simple. There are no moving parts other than the air compressor and the cooling system, so the noise is very low during operation.
Fuel cell disadvantage
1. High battery production cost
The fuel cell itself has a simple structure and has few components. However, the most common proton exchange membrane fuel cells require platinum metal, which is scarce in platinum resources and high in price, which leads to an increase in the production cost of the fuel cell.
2. High fuel production costs
At present, most of the fuel cells are mainly based on hydrogen energy, and the production of hydrogen is still mainly electrolyzed water, which requires power consumption to obtain hydrogen, resulting in high production costs.
3. High fuel storage
As the main fuel of current fuel cells, hydrogen requires high pressure and sealing during storage and transportation to ensure that it cannot leak. This places high demands on storage technology.
4. Insufficient supporting infrastructure
Although the fuel cell is slowly gaining popularity, its supporting infrastructure has not kept up. The electric vehicle resource network has learned that as of February 2018, there are 31 hydrogen refueling stations built and under construction in China, but the operation There are only 12 in the middle, which is not enough.
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