How electricity is generated?
Methods of generating electricity
Generating electricity from non-renewable sources:
How electricity is generated? Known as non — renewable energy as energy produced from enforceable sources or those that require very long periods of time for renewal, such as fossil fuels , which take millions of years to re — renovated again; Given that it is mainly composed of carbon, whose formation period extends from 300–360 million years, and fossil fuels are a valuable source of energy, the cost of production and extraction is relatively low, and it is characterized by ease of storage and transportation from one place to another, but at the same time it has effects.
Negative for the environment; The burning of fossil fuel particles causes air, water and soil pollution, and the increase in carbon dioxide levels in the atmosphere causes the so-called global warming, which is an increase in the percentage of greenhouse gases above their natural levels necessary for life. Among the most important forms of non-renewable energy used to generate electricity are the following:
Coal is used in many power plants because it is characterized by high efficiency in the production of electricity , it referred to as coal combustion processes are constantly being developed to raise the efficiency of combustion, The high efficiency of the combustion means reducing carbon emissions in the atmosphere, and called power generation cycle electrical using Coal has a Rankine Cycle, and it consists of four main parts.
The part responsible for pumping the water towards the boiler, and raising its pressure to an appropriate pressure value before entering the boiler.
Boiler: It is the boiling unit in the plant, as it heats the water and raises its temperature to become super heated steam.
How electricity is generated? In pulverized coal combustion systems, pulverized coal is blown into the combustion chamber of the boiler and burned at very high temperatures, which leads to heating the water in the boiler room and converting it into high pressure water vapor, and then the resulting vapor is released.
Through special tubes inside the boiler until it reaches the turbine.
Steam turbine: Water vapor with high temperature and pressure enters from the boiler towards the turbine due to the high pressure, where the water vapor pushes the turbine blades, which leads to their rotation and the rotation of the shaft connected to them, and this movement is used in the rotation of a coil of electrically conductive wires within a magnetic field, which leads to the generation of electricity according to The principle of electromagnetic induction.
Intensive: After the steam comes out of the turbine, its pressure decreases and enters the condenser to be cooled and returned to its liquid state before being pumped again during the cycle, and to cool the steam, water sources are used such as lakes or rivers, where water is pumped from them towards the condenser and returns to the source at a temperature higher than it was by 10–20 degrees Celsius, and in the absence of a nearby water source for electric power plants, cooling towers are used to cool the water vapor.
Natural gas is used in many electrical plants as a fuel for combustion, natural gas stations enjoy easy construction and efficient production of electricity, and the combustion of natural gas produces less quantities of nitrogen oxides, sulfur and other air pollutants compared to coal combustion products, and natural gas stations are divided into two types as follows:
Simple Gas Station: Its operating principle is the same as a coal-fired power plant, but it uses natural gas as fuel to generate electricity.
Composite gas station: The installed gas station consists of two units; A gas unit and a steam unit, and its idea is based on utilizing the energy generated by the high temperature gases coming out of the gas unit to produce additional quantities of water vapor needed to operate the steam turbine through the Energy Recovery Unit, which increases the turbine’s capacity to Generating electric power, and this plant is characterized by a high efficiency of up to 60% compared to a simple cycle, which has an efficiency of 34%.
Gas and Coal
How electricity is generated? Power plants that use gas and coal together are called cogeneration power plants, and they are characterized by high efficiency, and their idea is to take advantage of the water vapor coming from the turbine directly in industrial applications that need heat instead of condensing it and taking it out as a product of heat loss from the first cycle Thus, it reduces the economic burden and reduces air pollution.
The use of oil in electricity generation operations has decreased significantly in recent years; Because its combustion causes many different environmental damages, whether on the atmosphere with its harmful emissions or on the water sources and the lands around the power plants, as oil residues cannot be consumed during combustion completely and a large part of it is dumped as toxic and dangerous waste, and there are three techniques used to convert oil into Electricity, which is as follows:
How electricity is generated? Burning oil to produce the heat needed to heat water to high temperatures and generate water vapor.
Burning oil at high pressure and using the off-gases to directly rotate an electricity-generating turbine.
Burning oil in a combustion turbine using the heat of the gases, then circulating these gases to heat the water in the boiler to run the second turbine, and this technique is used in combined cycles.
Used material diesel fuel for some of the generation of electric power plants, The efficiency of the production of electricity from diesel higher than the efficiency of the production of coal, and diesel plants do not need large built spaces, and are usually used stations of backup in case of power outages from the base station, due to the high costs Diesel and the high cost of maintenance of the station, it did not enjoy a wide spread like other types of electric power plants.
The nuclear energy resulting from the nuclear fission process is used in nuclear reactors to generate the necessary heat to generate electricity in the plant, and the principle of work of nuclear power plants is not different from other stations except that the source of heat in heating water and converting it into steam is the nuclear fission reactor, where uranium material is used. As fuel in a nuclear reactor that produces the heat needed for fusion reactions, then it is cooled with cooling fluids and its heat is used in other parts of the nuclear plant, and it is worth noting that nuclear energy provides 11% of the global need for electricity, and Britain and France are the largest producers of this type Of energy.
Generating electricity from renewable sources
Renewable energy is called alternative energy; As it results from sources that are constantly replaceable and renewable, such as: solar energy, wind energy, water, energy, geothermal energy, and others, and with the beginning of the twenty-first century, renewable energy sources accounted for 20% of global energy consumption, as renewable energy is characterized by a low Their carbon emissions and thus their use reduces environmental pollution in general. Among the most prominent forms of renewable energy used in generating electricity are the following:
Solar energy is defined as the energy produced by the sun, and it is one of the cleanest and most important renewable energy sources. It has many uses, the most important of which are generating electricity, heating, water, providing lighting, and so on, Photovoltaics that convert solar radiation into electrical energy.
How electricity is generated? Photovoltaic cells are made of semiconducting materials such as silicon, so that it is treated to close to 100% purity, then it is called polycrystalline silicon, and its appearance becomes a pure crystal, and it is injected with boron or phosphorous, forming polysilicon cells of the type (P) or (N) ), As inside the polysilicon that was injected with boron represents the type (P) and carries the positive charge, and the polysilicon cells that have been injected with phosphorous represent the type (N) and carries the negative charge, and the photoelectric chips are formed by melting one of the two materials and then coating them with the other material To produce a region of intersection between them called (PN), and when the photovoltaic cells are exposed to sunlight represented by the photons in the light, the electrons are stimulated and move from the negative terminal to the positive terminal, forming an electrical circuit that generates an electric current.
Electricity is generated from wind energy using wind turbines that are suspended at high altitudes from the ground level, so that they face the movement of the winds and are able to exploit the largest amount of wind energy facing them, and these turbines consist of several main parts as follows:
They are facing the wind and installed at a specific angle that leads to its rotation, and the turbine blades with the front of the turbine represent the rotating part of the wind turbine.
Low speed shaft : This shaft rotates with the rotor at the same speed and is connected with a transmission.
Transmission: Its function is to increase the rotational speed of the low-speed shaft through the use of a system of gears that increases the speed. High speed shaft: It is connected to the transmission at one end and rotates at the speed caused by the transmission, while its other end rotates inside the generator.
The electric generator: It consists of two main parts: the rotating part represented by the high-speed rotating shaft, and the stator part, which represents a magnetic field in which the shaft rotates to produce electrical energy.
As for the rest of the wind turbine, they are special parts for speed control, steering, protection and stopping systems.
Electricity is generated from water energy by exploiting the force and speed of water flow from high altitudes such as waterfalls areas, the higher the height of the flowing water source, the higher its potential energy, which will be converted into kinetic energy, which is used to move the blades of huge water turbines connected to electric generators, and the hydroelectric power stations contain water tanks and valves To control the amount of water flowing from the reservoir.
Hydroelectric energy can be used to generate electricity in three ways, as follows:
Storing water in dams at high altitudes, then opening the gates of the dams and exploiting the higher potential energy when water flows in operating water turbines, rotating their blades, and operating the electric generator.
Using a series of canals to direct the flow of water from rivers to sites for hydro turbines to power them.
Using electricity from solar energy, wind and nuclear energy to pump water to high sites, and store it there to be used when needed hydroelectric energy.
This method is considered a method of storing electrical energy and converting it to potential energy.
Biomass is a form of organic fuel and a renewable source of energy used to generate electricity, examples include sawdust, some types of agricultural crops, some organic waste, and organic fertilizers, as the biomass is burned in bio-energy plants to obtain the necessary heat To produce the steam that powers the steam turbine to generate electricity, biomass combustion is characterized by the fact that its emissions are lower than those of fossil fuels, so it is less harmful to the environment.
Energy known geothermal as heat inside the Earth, which carry hot water or water vapor to the surface of the earth, and energy, geothermal many benefits, such as heating applications and cooling, as well as considered as a form of renewable forms of energy used in electric power generation, and based stations Geothermal energy is based on water vapor resulting from hot water sources in the ground, as this steam drives the steam turbine in the generation station and thus the electric generator works to produce electricity, and geothermal power plants have three different types as follows:
Dry Steam Plants
Dry Steam The water vapor is pumped from its underground sources directly to the electric power station to be used in the turbine to power the generator.
Flash Steam stations: They are the most common geothermal power stations, where they use underground water tanks with temperatures exceeding 182 degrees Celsius, as this water flows due to its high pressure to the surface of the earth, which reduces its pressure, and part of it boils into water vapor that is separated from the water and used for the operation
The steam turbine to generate electricity, then return the flowing water to the ground to bring about the previous process continuously and make it a renewable source of energy.
Binary Steam stations:Water with a relatively low temperature, i.e. 107–182 ° C, is used to heat another liquid, usually an organic compound with a low boiling point, and this fluid is evaporated in a heat exchanger, and the resulting heat is used to operate the steam turbine, then the water returns to the ground to reheat it And the liquid remains separated from the water without any mixing between them.
Electric power generation
Electricity generation is represented by the transfer of energy from its primary sources Such as fossil fuels, uranium energy, the kinetic energy of water and wind, and other primary energy sources into electrical energy that can be utilized, and each type of primary energy source has special technologies through which electrical energy can be generated, as electricity is generated in generating stations of various kinds; Such as coal plants, gas stations, nuclear power plants, and renewable energy plants; Such as solar power stations, wind power stations, hydroelectric power stations, biomass stations, and geothermal power stations, and each type of station has a different technology from the other in the production of electrical energy.