A hydrogen fuel cell is a battery that uses hydrogen as a chemical element to store energy. The basic principle is the reverse reaction of electrolyzed water, which supplies hydrogen and oxygen to the anode and cathode respectively. After hydrogen diffuses outward through the anode and reacts with the electrolyte, the electrons are released to the cathode through an external load.
Hydrogen fuel cell is different from other batteriesA dry battery and a battery are energy storage devices that store electrical energy and release it when needed. Hydrogen fuel cells are strictly a power generation device, like a power plant, that converts chemical energy directly into electrical energy. Chemical power generation unit. In addition, the electrode of the hydrogen fuel cell is made of a special porous material, which is a key technology of the hydrogen fuel cell. It not only provides a large contact surface for the gas and the electrolyte, but also catalyzes the chemical reaction of the battery. .
Hydrogen fuel cell application fieldAerospace field
In the 1960s, hydrogen fuel cells have been successfully used in the aerospace industry. The Apollo spacecraft between space and the Earth
Working diagram
This small, large capacity device is installed. After entering the 1970s, as people continue to master a variety of advanced hydrogen production technologies, hydrogen fuel cells will soon be used in power generation and automobiles.
Large-scale power stations, whether hydropower, thermal power or nuclear power, send the sent electricity to the grid and deliver it to the users. However, due to the different load of each household, the grid sometimes appears to be a peak, and sometimes it is a trough, which leads to power outages or voltage instability. In addition, about 70% of the combustion energy of conventional thermal power plants is consumed in huge equipment such as boilers and steam turbine generators, which consume a lot of energy and emit a lot of harmful substances. The use of hydrogen fuel cells to generate electricity directly converts the chemical energy of the fuel into electrical energy without burning. The energy conversion rate can reach 60% to 80%, and the pollution is small, the noise is small, and the device can be large or small and very flexible.
Hydrogen is chemically active and can be combined with many metals or alloys. After absorption of hydrogen by certain metals or alloys, a metal hydride is formed, some of which have a high hydrogen content, even higher than the density of liquid hydrogen, and the metal hydride decomposes under certain temperature conditions and The absorbed hydrogen is released, which constitutes a good hydrogen storage material.
Automotive application
Twenty China-developed hydrogen fuel cell cars were held at the New Energy Automobile Engineering Center of Tongji University, and they will be put into operation in the Olympic Games. The 20 hydrogen fuel cell cars were based on the Volkswagen Passat limousine model and were successfully developed through the restructuring and integration of the latest generation of fuel cell car powertrain platforms. They use hydrogen as an energy source to generate water through hydrogen peroxide reaction, which truly achieves zero pollution. Hydrogen fuel cell cars can run more than 300 kilometers with a single hydrogen, and the speed can reach 140~150 kilometers per hour. Hydrogen fuel cell cars are more than 200 kilograms more than the same type of diesel locomotives, more than five times more expensive.
Futian hydrogen fuel cell bus
The working principle of the hydrogen fuel cell vehicle is to send hydrogen gas to the anode plate (negative electrode) of the fuel cell. After the catalyst (platinum), one electron in the hydrogen atom is separated, and the hydrogen ions (protons) that have lost electrons pass through. The proton exchange membrane reaches the cathode plate (positive electrode) of the fuel cell, and the electrons cannot pass through the proton exchange membrane. This electron can only reach the cathode plate of the fuel cell via an external circuit, thereby generating a current in the external circuit. After the electron reaches the cathode plate, it recombines with oxygen atoms and hydrogen ions into water. Since oxygen supplied to the cathode plate can be obtained from the air, electric energy can be continuously supplied as long as hydrogen is continuously supplied to the anode plate, air is supplied to the cathode plate, and water (vapor) is taken away in time. The electricity generated by the fuel cell is supplied to the motor via an inverter, a controller, etc., and then the wheel is rotated by the transmission system, the drive axle, etc., so that the vehicle can travel on the road. Compared with traditional cars, the energy conversion efficiency of fuel cell vehicles is as high as 60-80%, which is 2 to 3 times that of internal combustion engines. The fuel cell fuel is hydrogen and oxygen. The product is clean water. It does not work to produce carbon monoxide and carbon dioxide, nor does it emit sulfur and particulates. Therefore, hydrogen fuel cell vehicles are truly zero-emission, zero-pollution vehicles, and hydrogen fuel is the perfect vehicle energy!
The advantages of hydrogen fuel cell vehicles are undoubted, and the disadvantages are obvious. With the advancement of technology, problems such as safety and hydrogen fuel storage technology that have plagued the development of hydrogen fuel cells have been gradually overcome and improved, but the cost problem remains the biggest bottleneck hindering the development of hydrogen fuel cell vehicles. The cost of hydrogen fuel cells is 100 times that of ordinary gasoline engines, and this price is unbearable in the market.
It is reported that the hydrogen fuel cell vehicles have a maximum output of 60 kilowatts and a fuel consumption of only 1.2 kilograms of hydrogen per 100 kilometers, which is equivalent to about 4 liters of 93 gasoline.
The British government will vigorously develop hydrogen fuel cell vehicles. It plans to maintain 1.6 million hydrogen fuel cell vehicles in the UK by 2030 and bring its market share to 30%-50% by 2050. The government will implement local production of hydrogen fuel cell vehicles from 2015, and develop related technologies on its own. In addition, hydrogen fuel supply stations will be built. [3]
At present, Toyota Motor Corporation has significantly reduced the cost of fuel cells. The price of the whole vehicle is controlled at US$69,000 (400,000 RMB), and it can provide 100KW power output with a battery life of 700 kilometers. It will be listed in North America and Japan, and will be available in the first half of 2015. [4]
Aircraft application
working principle
Fuel Cell is a kind of power generation device, but it is not discarded when it is used up like a normal non-rechargeable battery. It is not like a rechargeable battery. If it is used up, it must continue to be charged. As the name suggests, the fuel cell continues to add fuel. The reason for maintaining its power is “hydrogenâ€, which is why it is classified as new energy. The operating principle of the fuel cell (Figure 1), that is, the battery contains two electrodes of yin and yang, respectively filled with electrolyte, and the two electrodes are composed of a membrane with permeability. Hydrogen enters the anode of the fuel cell, and oxygen (or air) enters the fuel cell from the cathode. Through the action of the catalyst, the hydrogen molecules of the anode are decomposed into two protons and two electrons, wherein the protons are 'attracted' by oxygen to the other side of the film, and the electrons form a current through the external circuit and reach the cathode. . Under the action of the cathode catalyst, protons, oxygen and electrons react to form water molecules, so water can be said to be the only emission of fuel cells. The "hydrogen" fuel used in fuel cells can be derived from hydrogen produced by electrolysis of water and any hydrocarbons such as natural gas, methanol, ethanol (alcohol), biogas, and the like. Since the fuel cell generates current and water through the chemical reaction using hydrogen and oxygen, it is not completely pollution-free, and avoids the problem of time-consuming charging of the conventional battery. It is the most promising new energy mode at present, and can be popularized and applied. In vehicles and other highly polluting power generation tools, it will significantly reduce air pollution and the greenhouse effect.
Hydrogen fuel cell aircraft
Hourly speed
On April 3, 2008, Boeing successfully tested a small aircraft powered by hydrogen fuel cells. Boeing said this is the first time in the history of world aviation, indicating that the aviation industry will be more environmentally friendly in the future. But Boeing admits that this technology is unlikely to provide the main driving force for large passenger aircraft.
Boeing conducted a test flight of hydrogen fuel cell aircraft in the town of Okana, Spain from February to March 2008. The successful flight test has historical significance. The small aircraft take off and climb using the hybrid power provided by conventional batteries and hydrogen fuel cells. After climbing to a cruising altitude of 1000 meters above sea level, the aircraft cuts off the traditional battery power and supplies power only by hydrogen fuel cells. The plane flew at an altitude of 1000 meters for about 20 minutes at a speed of about 100 kilometers per hour. This technology is of great significance to Boeing and also makes the future of the aviation industry “full of green hopeâ€.
The small aircraft was converted from the Austrian "Diamond" two-seat propeller powered glider with a proton exchange membrane fuel cell and a lithium-ion battery. The small aircraft has a wingspan of 16.3 meters, a body length of 6.5 meters and a weight of about 800 kilograms. It can accommodate two people. During the flight test, there was only one pilot on board.
In the cabin, the traditional battery is placed in the only passenger seat, and behind the pilot there is an oxygen tank similar to that used by divers. Boeing said that the aircraft can fly for up to 45 minutes in a row, "no noise." Hydrogen fuel cells generate electricity by the process of converting hydrogen into water without generating greenhouse gases. In addition to heat, water vapor is the only by-product of hydrogen fuel cells.
Boeing's hydrogen fuel cell aircraft brings technological breakthroughs, but the Boeing (Europe) Research and Technology Division said. This technology may provide auxiliary power for large aircraft, but this requires a technological breakthrough.
Hydrogen fuel cell technology limitationsDemand for cleaner, safer and more efficient vehicles is growing rapidly in the face of rising fuel prices, environmental pollution and global warming.
Boeing's hydrogen fuel cell aircraft brings technological breakthroughs, but Boss (Europe) research and technology director Escarti said that hydrogen fuel cells can provide flight power for small aircraft, but can not provide the main power for large passenger aircraft.
Nieves La Pena, an engineer at Boeing's flight test, said the technology could provide auxiliary power for large aircraft, but it required technological breakthroughs. Boeing said it will continue to develop the potential of hydrogen fuel cells to improve the environment.
The International Energy Agency said that the promotion of the use of hydrogen and hydrogen fuel cells can reduce the energy consumption of three kinds of greenhouse gases, namely oil, natural gas and coal.
Hydrogen fuel cell vehicle principleA hydrogen fuel cell refers to a device in which hydrogen generates electricity through a chemical reaction with oxygen (a "hydrogen internal combustion engine" driven solely by combustion of hydrogen, which has also appeared, such as BMW's hydrogen energy 7 series). The driving force of a hydrogen fuel cell vehicle comes from a motor like a pure electric vehicle. Therefore, a hydrogen fuel cell vehicle can be understood as a "electric vehicle with a hydrogen fuel generator."
principle
In the fuel cell stack, a reaction in which hydrogen and oxygen are combined is carried out, in which a charge transfer occurs to generate an electric current. At the same time, hydrogen reacts with the oxidative reaction to form water.
The fuel cell stack acts as a chemical reaction cell, and its most critical technology core is the “proton exchange membraneâ€. On both sides of the film, the catalyst layer is closely attached to decompose the hydrogen into a charged ion state. Because the hydrogen molecule is small in volume, the electron-carrying hydrogen can be released to the opposite side through the tiny pores of the film, but the electron-carrying hydrogen crosses. During this film hole, electrons are stripped from the molecule leaving only positively charged hydrogen protons through the film to the other end.
Hydrogen protons are attracted to the electrodes on the other side of the film in combination with oxygen molecules. The electrode plates on both sides of the membrane split hydrogen into hydrogen ions positively and electrons, oxygen into oxygen atoms to capture electrons into oxygen ions (negative electricity), electrons form current between the electrode plates, and 2 hydrogen ions and One oxygen ion combines into water, and water becomes the only "waste" in the reaction. In essence, the entire operation process is the power generation process. As the oxidation progresses, the electrons are constantly transferred to form the current required to drive the car.
How hydrogen fuel cells work
Advantage
Excellent energy saving and environmental performance
Throughout the operation of the hydrogen fuel cell, in addition to the consumption of oxygen and air, there is no other energy consumption, no fueling or charging, and energy-saving performance is beyond doubt. At the same time, the hydrogen fuel cell stack only produces water in the process of producing electrical energy, so its biggest advantage is the real realization of the "zero emission" goal.
easy to accomplish
The practical application of the hydrogen-burning engine is relatively easy to implement. The traditional internal combustion engine structure can burn hydrogen with only a slight modification, and can make full use of the existing vehicle engine production lines and supporting facilities in the world, so it is currently used for vehicle engine hydrogen energy applications. The most economical and most widely used solution. In addition, hydrogen internal combustion engines do not have the same requirements for hydrogen fuel purity as fuel cells, and traditional automotive manufacturers have gained a lot of experience in internal combustion engine applications.
Fuel replenishment time is comparable to fuel vehicles
Hydrogen fuel cell vehicles are very fast and convenient to process hydrogen. The dedicated hydrogenation equipment can be filled with hydrogen raw materials in just 3 minutes. The advantages are obvious compared to the ultra-long charging waiting time of pure electric vehicles.
Performance is called fuel truck
As a hydrogen fuel cell vehicle, the Audi A7Sportbackh-tronquattro is equipped with a motor with a maximum output of 85Kw and a maximum torque of 270Nm. The total power is 170Kw and the torque is up to 540Nm. The car accelerates from 0-100Km for 7.9 seconds and has a top speed of 180Km/h, which is comparable to gasoline.
Application prospects
The advantages of hydrogen fuel cells are unimaginable. If pure hydrogen is used, its production products are only water, pollution-free, noise-free, high efficiency, and good responsiveness. Hydrogen fuel cells can be used as a green power source for automobiles not only in automobiles, but also as a large-scale hydrogen fuel power station in the industry. The future is self-evident. The fuel cell in the entire hydrogen energy system technology is played by the famous Canadian scientist Scott as the "chip" of the energy system, which plays an important role in the energy supply. It extends to the entire national economy and social development, as well as the people. Life plays an indispensable role.
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