Electricity generation
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Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery (transmission, distribution, etc.) to end users or its storage (using, for example, the pumped-storage method).
Usable electricity is not freely available in nature, so it must be "produced" (that is, transforming other forms of energy to electricity). Production is carried out in
History
The fundamental principles of electricity generation were discovered in the 1820s and early 1830s by British scientist
Commercial electricity production started with the coupling of the dynamo to the hydraulic turbine. The mechanical production of electric power began the
Electricity generation at central power stations started in 1882, when a
The first power plants used water power or coal.[7] Today a variety of energy sources are used, such as coal, nuclear, natural gas, hydroelectric, wind, and oil, as well as solar energy, tidal power, and geothermal sources.
In the 1880s the popularity of electricity grew massively with the introduction of the Incandescent light bulb. Although there are 22 recognised inventors of the light bulb prior to Joseph Swan and Thomas Edison, Edison and Swan's invention became by far the most successful and popular of all. During the early years of the 19th century, massive jumps in electrical sciences were made. And by the later 19th century the advancement of electrical technology and engineering led to electricity being part of everyday life. With the introduction of many electrical inventions and their implementation into everyday life, the demand for electricity within homes grew dramatically. With this increase in demand, the potential for profit was seen by many entrepreneurs who began investing into electrical systems to eventually create the first electricity public utilities. This process in history is often described as electrification.[8]
The earliest distribution of electricity came from companies operating independently of one another. A consumer would purchase electricity from a producer, and the producer would distribute it through their own power grid. As technology improved so did the productivity and efficiency of its generation. Inventions such as the steam turbine had a massive impact on the efficiency of electrical generation but also the economics of generation as well. This conversion of heat energy into mechanical work was similar to that of steam engines, however at a significantly larger scale and far more productively. The improvements of these large-scale generation plants were critical to the process of centralised generation as they would become vital to the entire power system that we now use today.
Throughout the middle of the 20th century many utilities began merging their distribution networks due to economic and efficiency benefits. Along with the invention of long-distance power transmission, the coordination of power plants began to form. This system was then secured by regional system operators to ensure stability and reliability. The electrification of homes began in Northern Europe and in the Northern America in the 1920s in large cities and urban areas. It was not until the 1930s that rural areas saw the large-scale establishment of electrification.[9]
Methods of generation
Several fundamental methods exist to convert other forms of energy into electrical energy. Utility-scale generation is achieved by rotating
Generators
Electric generators transform kinetic energy into electricity. This is the most used form for generating electricity and is based on Faraday's law. It can be seen experimentally by rotating a magnet within closed loops of conducting material (e.g. copper wire). Almost all commercial electrical generation is done using electromagnetic induction, in which mechanical energy forces a generator to rotate.
Electrochemistry
Photovoltaic effect
The
Economics
The selection of electricity production modes and their economic viability varies in accordance with demand and region. The economics vary considerably around the world, resulting in widespread residential selling prices.
Nuclear power plants can produce a huge amount of power from a single unit. However, nuclear disasters have raised concerns over the safety of nuclear power, and the capital cost of nuclear plants is very high. Hydroelectric power plants are located in areas where the potential energy from falling water can be harnessed for moving turbines and the generation of power. It may not be an economically viable single source of production where the ability to store the flow of water is limited and the load varies too much during the annual production cycle.
Generating equipment
Electric generators were known in simple forms from the discovery of electromagnetic induction in the 1830s. In general, some form of prime mover such as an engine or the turbines described above, drives a rotating magnetic field past stationary coils of wire thereby turning mechanical energy into electricity.[14] The only commercial scale forms of electricity production that do not employ a generator are photovoltaic solar and fuel cells.
Turbines
Almost all commercial electrical power on Earth is generated with a
- Steam
- Water is boiled by thermal power plant. About 41% of all electricity is generated this way.[15]
- Nuclear fission heat created in a nuclear reactor creates steam. Less than 15% of electricity is generated this way.
- Renewable energy. The steam is generated by biomass, solar thermal energy, or geothermal power.
- Water is boiled by
- Natural gas: turbines are driven directly by gases produced by combustion. Combined cycle are driven by both steam and natural gas. They generate power by burning natural gas in a gas turbineand use residual heat to generate steam. At least 20% of the world's electricity is generated by natural gas.
- Water Energy is captured by a water turbine from the movement of water - from falling water, the rise and fall of tides or ocean thermal currents (see ocean thermal energy conversion). Currently, hydroelectric plants provide approximately 16% of the world's electricity.
- The windmill was a very early wind turbine. In 2018 around 5% of the world's electricity was produced from wind
Turbines can also use other heat-transfer liquids than steam. Supercritical carbon dioxide based cycles can provide higher conversion efficiency due to faster heat exchange, higher energy density and simpler power cycle infrastructure. Supercritical carbon dioxide blends, that are currently in development, can further increase efficiency by optimizing its critical pressure and temperature points.
Although turbines are most common in commercial power generation, smaller generators can be powered by gasoline or diesel engines. These may used for backup generation or as a prime source of power within isolated villages.
World production
Total world generation in 2021 was 28,003 TWh, including coal (36%), gas (23%), hydro (15%), nuclear (10%), wind (6.6%), solar (3.7%), oil and other fossil fuels (3.1%), biomass (2.4%) and geothermal and other renewables (0.33%).[10]
Production by country
China produced a third of the world's electricity in 2021, largely from coal. The United States produces half as much as China but uses far more natural gas and nuclear.[10]
Environmental concerns
Variations between countries generating electrical power affect concerns about the environment. In France only 10% of electricity is generated from
According to the International Energy Agency (IEA), low-carbon electricity generation needs to account for 85% of global electrical output by 2040 in order to ward off the worst effects of climate change.[21] Like other organizations including the Energy Impact Center (EIC)[22] and the United Nations Economic Commission for Europe (UNECE),[23] the IEA has called for the expansion of nuclear and renewable energy to meet that objective.[24] Some, like EIC founder Bret Kugelmass, believe that nuclear power is the primary method for decarbonizing electricity generation because it can also power direct air capture that removes existing carbon emissions from the atmosphere.[25] Nuclear power plants can also create district heating and desalination projects, limiting carbon emissions and the need for expanded electrical output.[26]
A fundamental issue regarding centralised generation and the current electrical generation methods in use today is the significant negative environmental effects that many of the generation processes have. Processes such as coal and gas not only release carbon dioxide as they combust, but their extraction from the ground also impacts the environment. Open pit coal mines use large areas of land to extract coal and limit the potential for productive land use after the excavation. Natural gas extraction releases large amounts of methane into the atmosphere when extracted from the ground greatly increase global greenhouse gases. Although nuclear power plants do not release carbon dioxide through electricity generation, there are risks associated with nuclear waste and safety concerns associated with the use of nuclear sources.
Per unit of electricity generated coal and gas-fired power life-cycle greenhouse gas emissions are almost always at least ten times that of other generation methods.[27]
Centralised and distributed generation
Centralised generation is electricity generation by large-scale centralised facilities, sent through transmission lines to consumers. These facilities are usually located far away from consumers and distribute the electricity through high voltage transmission lines to a substation, where it is then distributed to consumers; the basic concept being that multi-megawatt or gigawatt scale large stations create electricity for a large number of people. The vast majority of electricity used is created from centralised generation. Most centralised power generation comes from large power plants run by fossil fuels such as coal or natural gas, though nuclear or large hydroelectricity plants are also commonly used.[28] Centralised generation is fundamentally the opposite of distributed generation. Distributed generation is the small-scale generation of electricity to smaller groups of consumers. This can also include independently producing electricity by either solar or wind power. In recent years distributed generation as has seen a spark in popularity due to its propensity to use renewable energy generation methods such as rooftop solar.[29]
Technologies
Centralised energy sources are large power plants that produce huge amounts of electricity to a large number of consumers. Most power plants used in centralised generation are thermal power plants meaning that they use a fuel to heat steam to produce a pressurised gas which in turn spins a turbine and generates electricity. This is the traditional way of producing energy. This process relies on several forms of technology to produce widespread electricity, these being natural coal, gas and nuclear forms of thermal generation. More recently solar and wind have become large scale.
Solar
A photovoltaic power station, also known as a solar park, solar farm, or solar power plant, is a large-scale grid-connected photovoltaic power system (PV system) designed for the supply of merchant power. They are different from most building-mounted and other decentralized solar power because they supply power at the utility level, rather than to a local user or users. Utility-scale solar is sometimes used to describe this type of project.
This approach differs from
In some countries, the
Wind
A wind farm or wind park, also called a wind power station or wind power plant,[33] is a group of wind turbines in the same location used to produce electricity. Wind farms vary in size from a small number of turbines to several hundred wind turbines covering an extensive area. Wind farms can be either onshore or offshore.
Many of the largest operational onshore wind farms are located in China, India, and the United States. For example, the
Coal
A
A coal-fired power station is a type of fossil fuel power station. The coal is usually pulverized and then burned in a pulverized coal-fired boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines that turn generators. Thus chemical energy stored in coal is converted successively into thermal energy, mechanical energy and, finally, electrical energy.
Coal-fired power stations emit over 10 billion tonnes ofNatural gas
Natural gas is ignited to create pressurised gas which is used to spin turbines to generate electricity. Natural gas plants use a gas turbine where natural gas is added along with oxygen which in turn combusts and expands through the turbine to force a generator to spin.
Natural gas power plants are more efficient than coal power generation, they however contribute to climate change but not as highly as coal generation. Not only do they produce carbon dioxide from the ignition of natural gas, but also the extraction of gas when mined releases a significant amount of methane into the atmosphere.[57]
Nuclear
Nuclear power plants create electricity through steam turbines where the heat input is from the process of nuclear fission. Currently, nuclear power produces 11% of all electricity in the world. Most nuclear reactors use uranium as a source of fuel. In a process called nuclear fission, energy, in the form of heat, is released when nuclear atoms are split. Electricity is created through the use of a nuclear reactor where heat produced by nuclear fission is used to produce steam which in turn spins turbines and powers the generators. Although there are several types of nuclear reactors, all fundamentally use this process.[58]
Normal emissions due to nuclear power plants are primarily waste heat and radioactive spent fuel. In a reactor accident, significant amounts of radioisotopes can be released to the environment, posing a long term hazard to life. This hazard has been a continuing concern of environmentalists. Accidents such as the
Electricity generation capacity by country
The table lists 45 countries with their total electricity capacities. The data is from 2022. According to the
Country | Total capacity (GW) |
Average per capita capacity (watts) |
---|---|---|
World | 8,890 | 1,120 |
China | 2,510 | 1,740 |
United States | 1,330 | 3,940 |
European Union | 1,080 | 2,420 |
India | 556 | 397 |
Japan | 370 | 2,940 |
Russia | 296 | 2,030 |
Germany | 267 | 3,220 |
Brazil | 222 | 1,030 |
Canada | 167 | 4,460 |
South Korea | 160 | 3,130 |
France | 148 | 2,280 |
Italy | 133 | 2,230 |
Spain | 119 | 2,580 |
United Kingdom | 111 | 1,640 |
Turkey | 107 | 1,240 |
Mexico | 104 | 792 |
Australia | 95.8 | 3,680 |
Saudi Arabia | 85.3 | 2,380 |
Iran | 83.3 | 977 |
Vietnam | 72.2 | 721 |
South Africa | 66.7 | 1,100 |
Poland | 64 | 1,690 |
Thailand | 63 | 901 |
Ukraine | 62.2 | 1,440 |
Egypt | 61.1 | 582 |
Taiwan | 58 | 2,440 |
Netherlands | 53.3 | 3,010 |
Sweden | 52.1 | 5,100 |
Argentina | 51.9 | 1,130 |
Pakistan | 42.7 | 192 |
Norway | 41.7 | 7,530 |
United Arab Emirates | 40.7 | 4,010 |
Malaysia | 37.9 | 1,110 |
Chile | 37 | 1,930 |
Venezuela | 34.1 | 1,210 |
Kazakhstan | 29.6 | 1,600 |
Switzerland | 27.8 | 2,960 |
Austria | 26.7 | 2,890 |
Algeria | 25.9 | 590 |
Greece | 24.4 | 2,400 |
Israel | 23.7 | 2,520 |
Finland | 22.2 | 3,980 |
Denmark | 21.3 | 3,710 |
Ireland | 13.3 | 2,420 |
New Zealand | 11.6 | 2,320 |
Iceland | 3.24 | 8,990 |
See also
- Glossary of power generation
- Cogeneration: the use of a heat engine or power station to generate electricity and useful heat at the same time.
- Cost of electricity by source
- Diesel generator
- Engine-generator
- Generation expansion planning
- Steam-electric power station
- World energy supply and consumption
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