Electricity generation is the process of generating electricity from primary energy sources. The peculiarity of electricity is that it is not primary energy, freely present in nature in significant quantities, and must be produced. The production of electricity occurs, as a rule, with the help of generators in industrial companies called power plants.
In the electric power industry, power generation is the first step in delivering electricity to end users, other steps are the transmission, distribution, storage and restoration of energy in pumping storage power plants.
Ways to generate electricity
The main way to produce electrical energy is to generate it by means of an electric generator that is on the same axis as the turbine, and convert the kinetic energy of the turbine rotation into electricity. Depending on the type of work agent that turns the turbine, the power plants are divided into hydraulic and thermal (including nuclear).
- Hydropower or hydroelectricity. Generate electricity through the force of water.
- Thermal energy. Electricity generation by burning fossil fuels.
- Nuclear energy. Production of electricity through nuclear fission reactions.
There are other ways of generating electricity that have several advantages over the "traditional" (mentioned above), but for various reasons they are not widespread. The main types of alternative energy are:
- Wind power. Obtaining electrical energy from the kinetic energy of the wind.
- Solar energy. Electricity generation through the photovoltaic effect.
- Geothermal energy. Production of electricity from heat inside the Earth.
- Hydrogen energy. Obtaining energy from the burning of hydrogen.
Hydropower is a renewable energy generation sector that uses the kinetic energy of a water stream to produce electricity. The energy production companies in this area are hydroelectric power plants, which are built in rivers.
During the construction of a hydroelectric power station with the help of dams in the rivers, a difference in the water surface levels is artificially created. The water, under the action of gravity, is poured from the upper pool to the lower one through special water pipes in which the water turbines are located, whose blades are not twisted by the flow of water. The turbine rotates the coaxial rotor of the generator.
A special type of hydroelectric power plant is pumping storage plants. They cannot be considered generating capacities in their pure form, since they consume almost as much electricity as they produce, however, such stations handle very effectively the discharge of the network at peak times.
It should also be noted such alternative types of hydroelectric power: tidal and energy wave. In these cases, the natural kinetic energy of marine tides and wind waves, respectively, is used to produce electrical energy. The proliferation of these types of electric power is hampered by the need for many factors to coincide when designing a power plant: a coast is needed where the tides (and sea waves, respectively) are strong and stable enough .
The companies of the thermal energy industry are thermal power plants, in which the thermal energy of fossil fuel combustion is converted into electrical energy. The generation of energy in thermal installations is considered a non- renewable energy source. Thermal power plants come in two main types:
Condensation, IES technology. A thermal condensation power plant, which is designed exclusively for the production of electricity. The heat obtained by burning the fuel heats the water in the steam generators, and the resulting superheated steam is supplied to the steam turbine, on the same axis with which there is an electric generator. In a turbine, the internal energy of the steam is converted by thermodynamic processes into mechanical energy, which in an electric generator generates an electric current supplied to the electricity grid. The exhaust vapor is discharged to the condenser. From there, the condensed water is pumped back to the steam generator.
Cogeneration, CHP technology. A cogeneration plant is a thermal power plant in which part of the thermal energy is directed to generate electrical energy, and part is supplied to heat the surrounding residential areas. The combined generation of heat and electrical energy in a thermal power plant significantly increases fuel efficiency compared to the generation of electricity separately in condensed power plants and heat for heating, in domestic boiler plants
The technological schemes of IES and CHP are similar, both use the same thermodynamic principles. The fundamental difference between the CHPP and the IES is that part of the steam generated in the boiler is used for heat supply needs.
Generation of electricity through nuclear energy
In nuclear energy for the generation of energy and heat using nuclear energy. Nuclear power companies are nuclear power plants. The principle of generating electricity in nuclear power plants is the same as in thermal power plants. Only in this case, thermal energy is not released during the burning of fossil fuels, but as a result of a nuclear reaction in a nuclear reactor.
The scheme for generating electricity is similar to that of thermal power plants: a steam generator receives heat from the reactor and generates steam, goes to a steam turbine, etc. Due to some design characteristics of nuclear power plants, it is profitable to use them only to generate electricity.
Photovoltaic Solar Energy
The production of electrical energy from the energy of solar radiation through the photoelectric effect. Photovoltaic panels convert sunlight directly into electricity. Although sunlight is free and abundant, large-scale production of electricity in solar power plants is more expensive than the production of electricity by electric generators. This is due to the high cost of solar panels, which, however, is constantly decreasing. On the other hand, one of the advantages of solar energy is that it is a renewable energy source.
Solar batteries with a conversion efficiency of almost 30% are currently commercially available. In experimental systems, more than 40% efficiency has been demonstrated. Until recently, photovoltaic devices were used more frequently in space orbital stations, in sparsely populated places where there is no access to a commercial power grid, or as an additional source of electricity for individual homes and businesses.
Recent advances in photovoltaic production and technology efficiency, along with subsidies due to environmental concerns, have significantly accelerated the deployment of photovoltaic solar energy. The disadvantages of wind energy and the disadvantages of solar energy are the need to create storage capacities for night operation (for solar energy) or without wind (for wind energy).
Geothermal energy for electric power generation
Geothermal energy is based on the industrial production of energy, in particular electricity, hot springs, thermal groundwater. In fact, geothermal stations are ordinary thermal power plants, in which underground heat sources from the bowels of the Earth are used instead of a boiler or a nuclear reactor as a heat source to heat steam through the laws of thermodynamics.
The disadvantages of geothermal energy are the geographical limitations of its application: from a thermodynamic and economic point of view it is profitable to build geothermal stations only in regions of tectonic activity, that is, where these natural sources of heat are the most affordable.
The use of hydrogen as an energy fuel has great prospects: hydrogen has a very high combustion efficiency, its resource is virtually unlimited, which would make it a renewable energy source. Hydrogen burning is absolutely environmentally friendly (distilled water is the product of combustion in an oxygen atmosphere).
However, hydrogen energy cannot fully meet the needs of mankind due to the high cost of producing pure hydrogen and the technical problems of its transportation in large quantities.
The production of electrochemical energy occurs in the process of direct conversion of energy from chemical bonds into electricity, such as in a battery. The generation of electrochemical energy is important in portable and mobile applications. Currently, most of the electrochemical energy comes from batteries. Primary cells, such as conventional zinc-carbon batteries, act directly as sources of energy, while secondary cells ( batteries) are used to store electricity and not to generate it. Open electrochemical systems known as fuel cells., Can be used to extract energy from natural or synthetic fuels.
In places where there is a lot of salt and fresh water, it is possible to create osmotic power plants.
The economy of power generation
The construction of electrical energy facilities is very expensive, its recovery period is long. The economic efficiency of a particular method of electricity generation depends on many parameters, mainly on the demand for electricity and the region. The sale prices of non-electric products also vary according to the relationship of these parameters.
The choice of the type of power plant is also based primarily on the consideration of local electricity needs and fluctuations in demand. In addition, all electrical networks have different charges, but power plants that are connected to the network and operate continuously must provide the basic load, the minimum daily consumption. The basic load can only be provided by large thermal and nuclear power plants, whose power can be regulated within certain limits. In hydroelectric plants, the ability to control energy is much lower.
Thermal power plants are preferably built in areas with a high density of industrial consumers. The negative impact of soil contamination by waste can be minimized, since power plants are generally located far from residential areas. Essential for a thermal power plant is the type of fuel burned. In general, the cheapest fuel for thermal power plants is coal. But if the price of natural gas falls below a certain limit, its use to generate electricity becomes more preferable than generating electricity by burning coal.
The main advantage of nuclear energy is the large capacity of each power unit with a relatively small size and high respect for the environment, with strict compliance with all operating standards. However, the potential dangers of the failure of a nuclear plant are very high.
Hydroelectric plants are generally built in remote areas and are extremely environmentally friendly, but their capacity varies greatly depending on the time of year, and they cannot regulate the energy delivered to the power grid over a wide range.
The cost of generating electricity from renewable sources (excluding hydroelectric power) has recently decreased significantly. The cost of electricity produced from solar energy, wind energy, tidal energy in many cases is already comparable to the cost of electricity produced in thermal power plants. Taking into account state subsidies, the construction of power plants that operate with renewable sources is economically feasible. However, the main drawback of such power plants is the inconsistent nature of their work and the inability to regulate their capacity.
History of electricity generation
The basic principle of power generation was discovered in the 1820s and early 1830s by British scientist Michael Faraday. His method, which is used today, is that in a closed conductor circuit when this circuit moves between the poles of a magnet, an electric current arises.
Electric generators installed in power plants centrally generate electricity in the form of alternating current. With the help of power transformers, the electrical voltage of the generated alternating current is increased, which allows it to be transmitted through cables with low losses. What a photovoltaic solar energy installation would make an electric current converter.
In the place of electric power consumption, the alternating current voltage is reduced by reducing transformers and transmitted to consumers. Electrification together with the Bessemer method of steelmaking became the basis of the Second Industrial Revolution. The main inventions that made electricity public and indispensable were made by Thomas Alva Edison and Nikola Tesla.
Electricity production at power plants began in 1882 when a steam engine at the Pearl Street station in New York launched a dynamo that produced direct current to illuminate Pearl Street. New technology was quickly introduced in many cities around the world that quickly turned lighting fans into electric power. Soon after, electric lamps began to be widely used in public buildings, in companies and for public transport (trams and trains). Since then, the production of electrical energy in the world has steadily increased.
- EIA - Electricity Data. (en) www.eia.gov
- L'Electricité en France en 2006 : une analyse statistique (fr) - DGEMP / Observatoire de l'énergie
- Regional PV Markets: Europe (en). Solarbuzz.com
Last review: September 12, 2019