A fuel cell is a device that efficiently generates heat and direct current as a result of an electrochemical reaction and uses hydrogen-rich fuel. By the principle of operation, it is similar to a battery. Structurally, the fuel cell is represented by a cathode, anode and electrolyte. How is it remarkable? Unlike the same batteries, hydrogen fuel cells do not accumulate electrical energy, do not need electricity to recharge and are not discharged. Power generation by the cells continues as long as they have a supply of air and fuel.
Features
The difference between fuel cells and other electricity generators is that during operation they do not burn fuel. In view of this feature, they do not need high-pressure rotors, do not emit loud noise and vibrations. Electricity in fuel cells is generated by a silent electrochemical reaction. The chemical energy of the fuel in such devices is converted directly to water, heat and electricity.
Fuel cells are highly efficient and do not produce large amounts of greenhouse gases. The emission product during the operation of the cells is a small amount of water in the form of steam and carbon dioxide, which is not released if pure hydrogen acts as a fuel.
Appearance story
In the 1950s and 1960s, NASA's emerging need for energy sources for long space missions provoked one of the most critical tasks for the fuel cells existing at that time. Alkaline elements use oxygen and hydrogen as fuel, which during the electrochemical reaction are converted into by-products useful during space flight - electricity, water and heat.
Fuel cells were first discovered at the beginning of the 19th century - in 1838. At the same time, the first information about their effectiveness appeared.
Work on fuel cells using alkaline electrolytes began in the late 1930s. Cells with nickel-plated electrodes under high pressure were invented only by 1939. During World War II, fuel cells consisting of alkaline cells with a diameter of about 25 centimeters were developed for British submarines.
Interest in them increased in the 1950s and 80s, characterized by a shortage of oil fuel. The countries of the world began to deal with issues of air pollution and the environment, striving to develop environmentally friendly methods for generating electricity. The technology for the production of fuel cells is currently undergoing active development.
Principle of operation
Heat and electricity are generated by fuel cells as a result of an electrochemical reaction using a cathode, anode and electrolyte.
The cathode and anode are separated by a proton-conducting electrolyte. After the oxygen enters the cathode and hydrogen to the anode, a chemical reaction is triggered, resulting in heat, current and water.
Molecular hydrogen dissociates on the anode catalyst, which leads to the loss of electrons. Hydrogen ions enter the cathode through an electrolyte, while electrons pass through an external electrical network and create a direct current, which is used to power the equipment. The oxygen molecule on the cathode catalyst combines with the electron and the incoming proton, eventually forming water, which is the only reaction product.
Types
The choice of a specific type of fuel cell depends on the area of its application. All fuel cells are divided into two main categories - high temperature and low temperature. The latter use pure hydrogen as fuel. Such devices typically require the conversion of primary fuel into pure hydrogen. The process is carried out using special equipment.
High-temperature fuel cells do not need this because they convert fuel at elevated temperatures, which eliminates the need for a hydrogen infrastructure.
The principle of operation of hydrogen fuel cells is based on the conversion of chemical energy into electrical energy without ineffective combustion processes and the transformation of thermal energy into mechanical energy.
General concepts
Hydrogen fuel cells are electrochemical devices that generate electricity as a result of highly efficient “cold” combustion of fuel. There are several types of such devices. The most promising technology are hydrogen-air fuel cells equipped with a PEMFC proton-exchange membrane.
The proton-conducting polymer membrane is designed to separate two electrodes - the cathode and the anode. Each of them is represented by a carbon matrix with a catalyst deposited on it. Molecular hydrogen dissociates on the anode catalyst, giving off electrons. Cations are passed to the cathode through the membrane, but the electrons are transferred to the external circuit because the membrane is not designed to transfer electrons.
The oxygen molecule on the cathode catalyst combines with the electron from the electric circuit and the incoming proton, eventually forming water, which is the only reaction product.
Hydrogen fuel cells are used for the manufacture of membrane-electrode blocks, which act as the main generating elements of the energy system.
Benefits of Hydrogen Fuel Cells
Among them are the following:
- Increased specific heat.
- Wide temperature range of operation.
- Lack of vibration, noise and a thermal spot.
- Reliability during cold start.
- The lack of self-discharge, which ensures a long shelf life of energy.
- Unlimited autonomy due to the possibility of adjusting energy intensity by changing the number of fuel cans.
- Providing virtually any energy intensity by changing the capacity of the hydrogen storage.
- Long term of operation.
- Silence and environmental friendliness of work.
- High level of energy intensity.
- Tolerance to external impurities in hydrogen.
Application area
Due to its high efficiency, hydrogen fuel cells are used in various fields:
- Portable Chargers
- Power supply systems for UAVs.
- Uninterruptible power supplies.
- Other devices and equipment.
Prospects for hydrogen energy
The widespread use of fuel cells for hydrogen peroxide will be possible only after creating an effective method for producing hydrogen. For the introduction of technology into active use, new ideas are required, with great expectations placed on the concept of biofuel elements and nanotechnology. Some companies relatively recently released effective catalysts based on various metals, at the same time there was information about the creation of fuel cells without membranes, which allowed to significantly reduce the cost of production and simplify the design of such devices. The advantages and characteristics of hydrogen fuel cells do not outweigh their main disadvantage - high cost, especially in comparison with hydrocarbon devices. The creation of one hydrogen power plant requires a minimum of 500 thousand dollars.
How to assemble a hydrogen fuel cell?
A fuel cell of small capacity can be created independently in a conventional home or school laboratory. As materials, an old gas mask, pieces of organic glass, an aqueous solution of ethyl alcohol and alkali are used.
The do-it-yourself hydrogen fuel cell body is made of plexiglass with a thickness of at least five millimeters. The partitions between the compartments can be of lesser thickness - about 3 millimeters. Plexiglass is glued with special glue made from chloroform or dichloroethane and plexiglass shavings. All work is carried out only with a working hood.
A hole with a diameter of 5-6 centimeters is drilled in the outer wall of the housing, into which a rubber stopper and a drain glass tube are inserted. Activated carbon from a gas mask is poured into the second and fourth compartment of the fuel cell housing - it will be used as an electrode.
The fuel will be circulated in the first chamber, while the fifth is filled with air, from which oxygen will be supplied. The electrolyte falling asleep between the electrodes is impregnated with a solution of paraffin and gasoline to prevent it from entering the air chamber. Copper plates with wires soldered to them are laid on a layer of coal, through which current will be discharged.
The assembled hydrogen fuel cell is charged with vodka diluted with water in a 1: 1 ratio. Caustic potassium is carefully added to the resulting mixture: 70 grams of potassium dissolves in 200 grams of water.
Before testing a hydrogen fuel cell, fuel is poured into the first chamber, and electrolyte into the third. The readings of the voltmeter connected to the electrodes should vary from 0.7 to 0.9 volts. To ensure continuous operation of the cell, spent fuel must be diverted, and new fuel should be poured through the rubber tube. By squeezing the tube, the feed rate is adjusted. Such hydrogen fuel cells, assembled at home, have little power.