Fuel cells

In modern technology, fuel cells are successfully used as sources of electric current. In them, at a fairly low temperature, the chemical form of energy is converted into electrical energy, and the current arises from the chemical interaction of flammable substances - hydrogen, gasoline, diesel fuel, coal, ammonia, metals with different oxidants, but most often with oxygen.

Fuel cells to their efficiency almost double the already existing thermal engines (steam turbines, diesel engines, etc.)

Fuel cells to their efficiency almost double the already existing thermal engines (steam turbines, diesel engines, etc.). In addition, they have no moving parts, are durable, operate without noise and do not form poisonous exhaust fumes and soot. In comparison with galvanic batteries, which operate for 12 hours, the life of the fuel cells reaches 100 hours.

Hydrogen-oxygen fuel cells became most widespread. Electrodes for them are made from catalytically active metals (sponge nickel or platinum - hydrogen electrode and active silver - oxygen), as an electrolyte use alkali, or acid solution. In these fuel cells, the cathode is washed by a stream of hydrogen, and the anode is a stream of oxygen. Electric current is generated by direct contact of three phases - gaseous (hydrogen, oxygen), liquid (alkali or acid solution) and solid (electrode material). On the surface of the cathode, hydrogen molecules lose their electrons and combine with hydroxide ions of the alkaline electrolyte. In this case, water molecules are obtained:

22 + 4OH- = 4H2O + 4e

At the anode, oxygen molecules are attached by electrons that move along the conductor from the cathode, combine with water molecules, resulting in the formation of hydroxide ions:

2 + 4 + 22 = 4-.

The most promising areas for the use of hydrogen-oxygen fuel cells are transport, nuclear power and hydropower. For example, at a small load of a power plant (for example, at night when a small number of electricity consumers work, the fuel cell functions as an electrolytic cell - it decomposes water and accumulates hydrogen and oxygen in high pressure gas tanks that are buried deep underground. When the power plant is overloaded, the hydrogen-oxygen element burns compressed hydrogen and oxygen, but works already as an electrochemical generator, that is, it produces an additional electric current.

Hydrogen-oxygen fuel cells are widely used in space technology - on artificial satellites and ships. They fully meet the need for electricity for powering radio and television equipment, appliances and household needs of astronauts. In addition, for long flights to space, the so-called biochemical fuel cells have acquired an uncommon value. In them, oxidation-reduction transformations are carried out with the help of microorganisms, as a result of which an electric current is generated. Under terrestrial conditions, such bioelements as fuel consume proteins, fats, starch, as well as fiber (straw, foliage, brushwood, etc.). In the conditions of space flight, waste of human life activity is processed in bioelements, and at the same time electric current, drinking water and harmless by-products (2, N2, salts).