Fossil fuel power station

Last updated

The 5,400 MW Belchatow Power Station in Poland - one of the world's largest coal-fired power stations. Belchatow-elektrownia.jpg
The 5,400  MW Bełchatów Power Station in Poland – one of the world's largest coal-fired power stations.
Share of electricity production from fossil fuels Share-electricity-fossil-fuels.svg
Share of electricity production from fossil fuels

2021 world electricity generation by source. Total generation was 28 petawatt-hours. [1]

Contents

  Coal (36%)
  Natural gas (23%)
  Hydro (15%)
  Nuclear (10%)
  Wind (7%)
  Solar (4%)
  Other (5%)

A fossil fuel power station is a thermal power station which burns a fossil fuel, such as coal, oil, or natural gas, to produce electricity. Fossil fuel power stations have machinery to convert the heat energy of combustion into mechanical energy, which then operates an electrical generator. The prime mover may be a steam turbine, a gas turbine or, in small plants, a reciprocating gas engine. All plants use the energy extracted from the expansion of a hot gas, either steam or combustion gases. Although different energy conversion methods exist, all thermal power station conversion methods have their efficiency limited by the Carnot efficiency and therefore produce waste heat.

Fossil fuel power stations provide most of the electrical energy used in the world. Some fossil-fired power stations are designed for continuous operation as baseload power plants, while others are used as peaker plants. However, starting from the 2010s, in many countries plants designed for baseload supply are being operated as dispatchable generation to balance increasing generation by variable renewable energy. [2]

By-products of fossil fuel power plant operation must be considered in their design and operation. Flue gas from combustion of the fossil fuels contains carbon dioxide and water vapor, as well as pollutants such as nitrogen oxides (NOx), sulfur oxides (SOx), and, for coal-fired plants, mercury, traces of other metals, and fly ash. Usually all of the carbon dioxide and some of the other pollution is discharged to the air. Solid waste ash from coal-fired boilers must also be removed.

Fossil fueled power stations are major emitters of carbon dioxide (CO2), a greenhouse gas which is a major contributor to global warming. The results of a recent study [3] show that the net income available to shareholders of large companies could see a significant reduction from the greenhouse gas emissions liability related to only natural disasters in the United States from a single coal-fired power plant. However, as of 2015, no such cases have awarded damages in the United States. Per unit of electric energy, brown coal emits nearly twice as much CO2 as natural gas, and black coal emits somewhat less than brown. As of 2019, carbon capture and storage of emissions is not economically viable for fossil fuel power stations, [4] and keeping global warming below 1.5 °C is still possible but only if no more fossil fuel power plants are built and some existing fossil fuel power plants are shut down early, together with other measures such as reforestation. [5] [6]

Basic concepts: heat into mechanical energy

In a fossil fuel power plant the chemical energy stored in fossil fuels such as coal, fuel oil, natural gas or oil shale and oxygen of the air is converted successively into thermal energy, mechanical energy and, finally, electrical energy. Each fossil fuel power plant is a complex, custom-designed system. Multiple generating units may be built at a single site for more efficient use of land, natural resources and labor. Most thermal power stations in the world use fossil fuel, outnumbering nuclear, geothermal, biomass, or concentrated solar power plants.

The second law of thermodynamics states that any closed-loop cycle can only convert a fraction of the heat produced during combustion into mechanical work. The rest of the heat, called waste heat, must be released into a cooler environment during the return portion of the cycle. The fraction of heat released into a cooler medium must be equal or larger than the ratio of absolute temperatures of the cooling system (environment) and the heat source (combustion furnace). Raising the furnace temperature improves the efficiency but complicates the design, primarily by the selection of alloys used for construction, making the furnace more expensive. The waste heat cannot be converted into mechanical energy without a cooler cooling system. However, it may be used in cogeneration plants to heat buildings, produce hot water, or to heat materials on an industrial scale, such as in some oil refineries, plants, and chemical synthesis plants.

Typical thermal efficiency for utility-scale electrical generators is around 37% for coal and oil-fired plants, [7] and 56 – 60% (LEV) for combined-cycle gas-fired plants. Plants designed to achieve peak efficiency while operating at capacity will be less efficient when operating off-design (i.e. temperatures too low.) [8]

Practical fossil fuels stations operating as heat engines cannot exceed the Carnot cycle limit for conversion of heat energy into useful work. Fuel cells do not have the same thermodynamic limits as they are not heat engines.

The efficiency of a fossil fuel plant may be expressed as its heat rate, expressed in BTU/kilowatthour or megajoules/kilowatthour.

Plant types

Steam

In a steam turbine power plant, fuel is burned in a furnace and the hot gasses flow through a boiler. Water is converted to steam in the boiler; additional heating stages may be included to superheat the steam. The hot steam is sent through controlling valves to a turbine. As the steam expands and cools, its energy is transferred to the turbine blades which turn a generator. The spent steam has very low pressure and energy content; this water vapor is fed through a condenser, which removes heat from the steam. The condensed water is then pumped into the boiler to repeat the cycle.

Emissions from the boiler include carbon dioxide, oxides of sulfur, and in the case of coal fly ash from non-combustible substances in the fuel. Waste heat from the condenser is transferred either to the air, or sometimes to a cooling pond, lake or river.

Gas turbine and combined gas/steam

480 megawatt GE H series power generation gas turbine GE H series Gas Turbine.jpg
480 megawatt GE H series power generation gas turbine
Currant Creek Power Plant near Mona, Utah is a natural gas fired electrical plant. Currant Creek Power Plant.jpg
Currant Creek Power Plant near Mona, Utah is a natural gas fired electrical plant.

One type of fossil fuel power plant uses a gas turbine in conjunction with a heat recovery steam generator (HRSG). It is referred to as a combined cycle power plant because it combines the Brayton cycle of the gas turbine with the Rankine cycle of the HRSG. The turbines are fueled either with natural gas or fuel oil.

Reciprocating engines

Diesel engine generator sets are often[ citation needed ] used for prime power in communities not connected to a widespread power grid. Emergency (standby) power systems may use reciprocating internal combustion engines operated by fuel oil or natural gas. Standby generators may serve as emergency power for a factory or data center, or may also be operated in parallel with the local utility system to reduce peak power demand charge from the utility. Diesel engines can produce strong torque at relatively low rotational speeds, which is generally desirable when driving an alternator, but diesel fuel in long-term storage can be subject to problems resulting from water accumulation and chemical decomposition. Rarely used generator sets may correspondingly be installed as natural gas or LPG to minimize the fuel system maintenance requirements.

Spark-ignition internal combustion engines operating on gasoline (petrol), propane, or LPG are commonly used as portable temporary power sources for construction work, emergency power, or recreational uses.

Reciprocating external combustion engines such as the Stirling engine can be run on a variety of fossil fuels, as well as renewable fuels or industrial waste heat. Installations of Stirling engines for power production are relatively uncommon.

Historically, the first central stations used reciprocating steam engines to drive generators. As the size of the electrical load to be served grew, reciprocating units became too large and cumbersome to install economically. The steam turbine rapidly displaced all reciprocating engines in central station service.

Fuels

Coal

Diagram of a typical steam-cycle coal power plant (proceeding from left to right) Coal fired power plant diagram.svg
Diagram of a typical steam-cycle coal power plant (proceeding from left to right)

Coal is the most abundant fossil fuel on the planet, and widely used as the source of energy in thermal power stations and is a relatively cheap fuel. Coal is an impure fuel and produces more greenhouse gas and pollution than an equivalent amount of petroleum or natural gas. For instance, the operation of a 1000-MWe coal-fired power plant results in a nuclear radiation dose of 490 person-rem/year, compared to 136 person-rem/year, for an equivalent nuclear power plant including uranium mining, reactor operation and waste disposal. [9]

Coal is delivered by highway truck, rail, barge, collier ship or coal slurry pipeline. Generating stations adjacent to a mine may receive coal by conveyor belt or massive diesel-electric-drive trucks. Coal is usually prepared for use by crushing the rough coal to pieces less than 2 inches (5 cm) in size.

Natural gas

Gas is a very common fuel and has mostly replaced coal in countries where gas was found in the late 20th century or early 21st century, such as the US and UK. Sometimes coal-fired steam plants are refitted to use natural gas to reduce net carbon dioxide emissions. Oil-fuelled plants may be converted to natural gas to lower operating cost.

Oil

Heavy fuel oil was once a significant source of energy for electric power generation. After oil price increases of the 1970s, oil was displaced by coal and later natural gas. Distillate oil is still important as the fuel source for diesel engine power plants used especially in isolated communities not interconnected to a grid. Liquid fuels may also be used by gas turbine power plants, especially for peaking or emergency service. Of the three fossil fuel sources, oil has the advantages of easier transportation and handling than solid coal, and easier on-site storage than natural gas.

Combined heat and power

Combined heat and power (CHP), also known as cogeneration, is the use of a thermal power station to provide both electric power and heat (the latter being used, for example, for district heating purposes). This technology is practiced not only for domestic heating (low temperature) but also for industrial process heat, which is often high temperature heat. Calculations show that Combined Heat and Power District Heating (CHPDH) is the cheapest method in reducing (but not eliminating) carbon emissions, if conventional fossil fuels remain to be burned. [10] [ unreliable source? ]

Environmental impacts

The Mohave Power Station, a 1,580 MW coal power station near Laughlin, Nevada, out of service since 2005 due to environmental restrictions Mohave Generating Station 1.jpg
The Mohave Power Station, a 1,580 MW coal power station near Laughlin, Nevada, out of service since 2005 due to environmental restrictions

Thermal power plants are one of the main artificial sources of producing toxic gases and particulate matter. Fossil fuel power plants cause the emission of pollutants such as NOx, SOx, CO2, CO, PM, organic gases and polycyclic aromatic hydrocarbons. [12] World organizations and international agencies, like the IEA, are concerned about the environmental impact of burning fossil fuels, and coal in particular. The combustion of coal contributes the most to acid rain and air pollution, and has been connected with global warming. Due to the chemical composition of coal there are difficulties in removing impurities from the solid fuel prior to its combustion. Modern day coal power plants pollute less than older designs due to new "scrubber" technologies that filter the exhaust air in smoke stacks. However, emission levels of various pollutants are still on average several times greater than natural gas power plants and the scrubbers transfer the captured pollutants to wastewater, which still requires treatment in order to avoid pollution of receiving water bodies. In these modern designs, pollution from coal-fired power plants comes from the emission of gases such as carbon dioxide, nitrogen oxides, and sulfur dioxide into the air, as well a significant volume of wastewater which may contain lead, mercury, cadmium and chromium, as well as arsenic, selenium and nitrogen compounds (nitrates and nitrites). [13]

Acid rain is caused by the emission of nitrogen oxides and sulfur dioxide. These gases may be only mildly acidic themselves, yet when they react with the atmosphere, they create acidic compounds such as sulfurous acid, nitric acid and sulfuric acid which fall as rain, hence the term acid rain. In Europe and the US, stricter emission laws and decline in heavy industries have reduced the environmental hazards associated with this problem, leading to lower emissions after their peak in 1960s.

In 2008, the European Environment Agency (EEA) documented fuel-dependent emission factors based on actual emissions from power plants in the European Union. [14]

PollutantHard coalBrown coalFuel oilOther oilGas
CO2 (g/GJ)94,600101,00077,40074,10056,100
SO2 (g/GJ)7651,3611,3502280.68
NOx (g/GJ)29218319512993.3
CO (g/GJ)89.189.115.715.714.5
Non methane organic compounds (g/GJ)4.927.783.703.241.58
Particulate matter (g/GJ)1,2033,254161.910.1
Flue gas volume total (m3/GJ)360444279276272

Carbon dioxide

Taichung coal-fired power plant in Taiwan, the world's largest carbon dioxide emitter Taichung Thermal Power Plant.JPG
Taichung coal-fired power plant in Taiwan, the world's largest carbon dioxide emitter

Electricity generation using carbon-based fuels is responsible for a large fraction of carbon dioxide (CO2) emissions worldwide and for 34% of U.S. man-made carbon dioxide emissions in 2010. In the U.S. 70% of electricity is generated by combustion of fossil fuels. [16]

Coal contains more carbon than oil or natural gas fossil fuels, resulting in greater volumes of carbon dioxide emissions per unit of electricity generated. In 2010, coal contributed about 81% of CO2 emissions from generation and contributed about 45% of the electricity generated in the United States. [17] In 2000, the carbon intensity (CO2 emissions) of U.S. coal thermal combustion was 2249 lbs/MWh (1,029 kg/MWh) [18] while the carbon intensity of U.S. oil thermal generation was 1672 lb/MWh (758 kg/MWh or 211 kg/GJ) [19] and the carbon intensity of U.S. natural gas thermal production was 1135 lb/MWh (515 kg/MWh or 143 kg/GJ). [20]

The Intergovernmental Panel on Climate Change (IPCC) reports that increased quantities of the greenhouse gas carbon dioxide within the atmosphere will "very likely" lead to higher average temperatures on a global scale (global warming). Concerns regarding the potential for such warming to change the global climate prompted IPCC recommendations calling for large cuts to CO2 emissions worldwide. [21]

Emissions can be reduced with higher combustion temperatures, yielding more efficient production of electricity within the cycle. As of 2019 the price of emitting CO2 to the atmosphere is much lower than the cost of adding carbon capture and storage (CCS) to fossil fuel power stations, so owners have not done so. [4]

Estimation of carbon dioxide emissions

The CO2 emissions from a fossil fuel power station can be estimated with the following formula: [22]

CO2 emissions = capacity x capacity factor x heat rate x emission intensity x time

where "capacity" is the "nameplate capacity" or the maximum allowed output of the plant, "capacity factor" or "load factor" is a measure of the amount of power that a plant produces compared with the amount it would produce if operated at its rated capacity nonstop, heat rate is thermal energy in/electrical energy out, emission intensity (also called emission factor) is the CO2 emitted per unit of heat generated for a particular fuel.

As an example, a new 1500 MW supercritical lignite-fueled power station running on average at half its capacity might have annual CO2 emissions estimated as:

= 1500MW x 0.5 x 100/40 x 101000 kg/TJ x 1year

= 1500MJ/s x 0.5 x 2.5 x 0.101 kg/MJ x 365x24x60x60s

= 1.5x103 x 5x10−1 x 2.5 x 1.01−1 x 3.1536x107 kg

= 59.7 x103-1-1+7 kg

= 5.97 Mt

Thus the example power station is estimated to emit about 6 megatonnes of carbon dioxide each year. The results of similar estimations are mapped by organisations such as Global Energy Monitor, Carbon Tracker and ElectricityMap.

Alternatively it may be possible to measure CO2 emissions (perhaps indirectly via another gas) from satellite observations. [23]

Particulate matter

Another problem related to coal combustion is the emission of particulates that have a serious impact on public health. Power plants remove particulate from the flue gas with the use of a bag house or electrostatic precipitator. Several newer plants that burn coal use a different process, Integrated Gasification Combined Cycle in which synthesis gas is made out of a reaction between coal and water. The synthesis gas is processed to remove most pollutants and then used initially to power gas turbines. Then the hot exhaust gases from the gas turbines are used to generate steam to power a steam turbine. The pollution levels of such plants are drastically lower than those of "classic" coal power plants. [24]

Particulate matter from coal-fired plants can be harmful and have negative health impacts. Studies have shown that exposure to particulate matter is related to an increase of respiratory and cardiac mortality. [25] Particulate matter can irritate small airways in the lungs, which can lead to increased problems with asthma, chronic bronchitis, airway obstruction, and gas exchange. [25]

There are different types of particulate matter, depending on the chemical composition and size. The dominant form of particulate matter from coal-fired plants is coal fly ash, but secondary sulfate and nitrate also comprise a major portion of the particulate matter from coal-fired plants. [26] Coal fly ash is what remains after the coal has been combusted, so it consists of the incombustible materials that are found in the coal. [27]

The size and chemical composition of these particles affects the impacts on human health. [25] [26] Currently coarse (diameter greater than 2.5 μm) and fine (diameter between 0.1 μm and 2.5 μm) particles are regulated, but ultrafine particles (diameter less than 0.1 μm) are currently unregulated, yet they pose many dangers. [25] Unfortunately much is still unknown as to which kinds of particulate matter pose the most harm, which makes it difficult to come up with adequate legislation for regulating particulate matter. [26]

There are several methods of helping to reduce the particulate matter emissions from coal-fired plants. Roughly 80% of the ash falls into an ash hopper, but the rest of the ash then gets carried into the atmosphere to become coal-fly ash. [27] Methods of reducing these emissions of particulate matter include:

  1. a baghouse
  2. an electrostatic precipitator (ESP)
  3. cyclone collector

The baghouse has a fine filter that collects the ash particles, electrostatic precipitators use an electric field to trap ash particles on high-voltage plates, and cyclone collectors use centrifugal force to trap particles to the walls. [27] A recent study indicates that sulfur emissions from fossil fueled power stations in China may have caused a 10-year lull in global warming (1998-2008). [28]

Wastewater

Wastestreams at a coal-fired power plant Coal power plant wastestreams - EPA.png
Wastestreams at a coal-fired power plant

Fossil-fuel power stations, particularly coal-fired plants, are a major source of industrial wastewater. Wastewater streams include flue-gas desulfurization, fly ash, bottom ash and flue gas mercury control. Plants with air pollution controls such as wet scrubbers typically transfer the captured pollutants to the wastewater stream. [13]

Ash ponds, a type of surface impoundment, are a widely used treatment technology at coal-fired plants. These ponds use gravity to settle out large particulates (measured as total suspended solids) from power plant wastewater. This technology does not treat dissolved pollutants. Power stations use additional technologies to control pollutants, depending on the particular wastestream in the plant. These include dry ash handling, closed-loop ash recycling, chemical precipitation, biological treatment (such as an activated sludge process), membrane systems, and evaporation-crystallization systems. In 2015 EPA published a regulation pursuant to the Clean Water Act that requires US power plants to use one or more of these technologies. [13] Technological advancements in ion exchange membranes and electrodialysis systems has enabled high efficiency treatment of flue-gas desulfurization wastewater to meet the updated EPA discharge limits. [29]

Radioactive trace elements

Coal is a sedimentary rock formed primarily from accumulated plant matter, and it includes many inorganic minerals and elements which were deposited along with organic material during its formation. As the rest of the Earth's crust, coal also contains low levels of uranium, thorium, and other naturally occurring radioactive isotopes whose release into the environment leads to radioactive contamination. While these substances are present as very small trace impurities, enough coal is burned that significant amounts of these substances are released. A 1,000 MW coal-burning power plant could have an uncontrolled release of as much as 5.2 metric tons per year of uranium (containing 74 pounds (34 kg) of uranium-235) and 12.8 metric tons per year of thorium. [30] In comparison, a 1,000 MW nuclear plant will generate about 30 metric tons of high-level radioactive solid packed waste per year. [31] It is estimated that during 1982, US coal burning released 155 times as much uncontrolled radioactivity into the atmosphere as the Three Mile Island incident. [32] The collective radioactivity resulting from all coal burning worldwide between 1937 and 2040 is estimated to be 2,700,000 curies or 0.101 EBq. [30] During normal operation, the effective dose equivalent from coal plants is 100 times that from nuclear plants. [30] Normal operation however, is a deceiving baseline for comparison: just the Chernobyl nuclear disaster released, in iodine-131 alone, an estimated 1.76 EBq. [33] of radioactivity, a value one order of magnitude above this value for total emissions from all coal burned within a century, while the iodine-131, the major radioactive substance which comes out in accident situations, has a half life of just 8 days.

Water and air contamination by coal ash

A study released in August 2010 that examined state pollution data in the United States by the organizations Environmental Integrity Project, the Sierra Club and Earthjustice found that coal ash produced by coal-fired power plants dumped at sites across 21 U.S. states has contaminated ground water with toxic elements. The contaminants including the poisons arsenic and lead. The study concluded that the problem of coal ash-caused water contamination is even more extensive in the United States than has been estimated. The study brought to 137 the number of ground water sites across the United States that are contaminated by power plant-produced coal ash. [34]

Arsenic has been shown to cause skin cancer, bladder cancer and lung cancer, and lead damages the nervous system. [35] Coal ash contaminants are also linked to respiratory diseases and other health and developmental problems, and have disrupted local aquatic life. [34] Coal ash also releases a variety of toxic contaminants into nearby air, posing a health threat to those who breathe in fugitive coal dust. [35]

Mercury contamination

U.S. government scientists tested fish in 291 streams around the country for mercury contamination. They found mercury in every fish tested, according to the study by the U.S. Department of the Interior. They found mercury even in fish of isolated rural waterways. Twenty five percent of the fish tested had mercury levels above the safety levels determined by the United States Environmental Protection Agency (EPA) for people who eat the fish regularly. The largest source of mercury contamination in the United States is coal-fueled power plant emissions. [36]

Conversion of fossil fuel power plants

Several methods exist to reduce pollution and reduce or eliminate carbon emissions of fossil fuel power plants. A frequently used and cost-efficient method is to convert a plant to run on a different fuel. This includes conversions of coal power plants to energy crops/biomass or waste [37] [38] [39] and conversions of natural gas power plants to biogas or hydrogen. [40] Conversions of coal powered power plants to waste-fired power plants have an extra benefit in that they can reduce landfilling. In addition, waste-fired power plants can be equipped with material recovery, which is also beneficial to the environment. In some instances, torrefaction of biomass may benefit the power plant if energy crops/biomass is the material the converted fossil fuel power plant will be using. [41] Also, when using energy crops as the fuel, and if implementing biochar production, the thermal power plant can even become carbon negative rather than just carbon neutral. Improving the energy efficiency of a coal-fired power plant can also reduce emissions.

Besides simply converting to run on a different fuel, some companies also offer the possibility to convert existing fossil-fuel power stations to grid energy storage systems which use electric thermal energy storage (ETES) [42]

Coal pollution mitigation

Coal pollution mitigation is a process whereby coal is chemically washed of minerals and impurities, sometimes gasified, burned and the resulting flue gases treated with steam, with the purpose of removing sulfur dioxide, and reburned so as to make the carbon dioxide in the flue gas economically[ citation needed ] recoverable, and storable underground (the latter of which is called "carbon capture and storage"). The coal industry uses the term "clean coal" to describe technologies designed to enhance both the efficiency and the environmental acceptability of coal extraction, preparation and use, [43] but has provided no specific quantitative limits on any emissions, particularly carbon dioxide. Whereas contaminants like sulfur or mercury can be removed from coal, carbon cannot be effectively removed while still leaving a usable fuel, and clean coal plants without carbon sequestration and storage do not significantly reduce carbon dioxide emissions. James Hansen in an open letter to then U.S. President Barack Obama advocated a "moratorium and phase-out of coal plants that do not capture and store CO2". In his book Storms of My Grandchildren , similarly, Hansen discusses his Declaration of Stewardship, the first principle of which requires "a moratorium on coal-fired power plants that do not capture and sequester carbon dioxide". [44]

Running the power station on hydrogen converted from natural gas

Gas-fired power plants can also be modified to run on hydrogen. [45] Hydrogen can at first be created from natural gas through steam reforming, as a step towards a hydrogen economy, thus eventually reducing carbon emissions. [46] [47]

Since 2013, the conversion process has been improved by scientists at Karlsruhe Liquid-metal Laboratory (KALLA), using a process called methane pyrolysis. [48] They succeeded in allowing the soot to be easily removed (soot is a byproduct of the process and damaged the working parts in the past -most notably the nickel-iron-cobaltcatalyst-). [49] [50] The soot (which contains the carbon) can then be stored underground and is not released into the atmosphere.

Phase out of fossil fuel power plants

As of 2019 there is still a chance of keeping global warming below 1.5 °C if no more fossil fuel power plants are built and some existing fossil fuel power plants are shut down early, together with other measures such as reforestation. [5] Alternatives to fossil fuel power plants include nuclear power, solar power, geothermal power, wind power, hydropower, biomass power plants and other renewable energies (see non-carbon economy). Most of these are proven technologies on an industrial scale, but others are still in prototype form.

Some countries only include the cost to produce the electrical energy, and do not take into account the social cost of carbon or the indirect costs associated with the many pollutants created by burning coal (e.g. increased hospital admissions due to respiratory diseases caused by fine smoke particles). [51]

Relative cost by generation source

When comparing power plant costs, it is customary[ clarification needed ] to start by calculating the cost of power at the generator terminals by considering several main factors. External costs such as connections costs, the effect of each plant on the distribution grid are considered separately as an additional cost to the calculated power cost at the terminals.

Initial factors considered are:

These costs occur over the 30–50 year life[ clarification needed ] of the fossil fuel power plants, using discounted cash flows.

See also

Related Research Articles

<span class="mw-page-title-main">Coal</span> Combustible sedimentary rock composed primarily of carbon

Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is a type of fossil fuel, formed when dead plant matter decays into peat which is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits of coal originate in former wetlands called coal forests that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times.

<span class="mw-page-title-main">Electricity generation</span> Process of generating electrical power

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 to end users or its storage, using for example, the pumped-storage method.

<span class="mw-page-title-main">Power station</span> Facility generating electric power

A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid.

<span class="mw-page-title-main">Gasification</span> Form of energy conversion

Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases, including as the largest fractions: nitrogen (N2), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (CO2). This is achieved by reacting the feedstock material at high temperatures (typically >700 °C), without combustion, via controlling the amount of oxygen and/or steam present in the reaction. The resulting gas mixture is called syngas (from synthesis gas) or producer gas and is itself a fuel due to the flammability of the H2 and CO of which the gas is largely composed. Power can be derived from the subsequent combustion of the resultant gas, and is considered to be a source of renewable energy if the gasified compounds were obtained from biomass feedstock.

<span class="mw-page-title-main">Fluidized bed combustion</span> Technology used to burn solid fuels

Fluidized bed combustion (FBC) is a combustion technology used to burn solid fuels.

<span class="mw-page-title-main">Solid fuel</span> Solid material that can be burnt to release energy

Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion. Solid fuels can be contrasted with liquid fuels and gaseous fuels. Common examples of solid fuels include wood, charcoal, peat, coal, hexamine fuel tablets, dry dung, wood pellets, corn, wheat, rice, rye, and other grains. Solid fuels are extensively used in rocketry as solid propellants. Solid fuels have been used throughout human history to create fire and solid fuel is still in widespread use throughout the world in the present day.

<span class="mw-page-title-main">Wood fuel</span> Wood used as fuel for combustion

Wood fuel is a fuel such as firewood, charcoal, chips, sheets, pellets, and sawdust. The particular form used depends upon factors such as source, quantity, quality and application. In many areas, wood is the most easily available form of fuel, requiring no tools in the case of picking up dead wood, or few tools, although as in any industry, specialized tools, such as skidders and hydraulic wood splitters, have been developed to mechanize production. Sawmill waste and construction industry by-products also include various forms of lumber tailings.

<span class="mw-page-title-main">Environmental impact of electricity generation</span>

Electric power systems consist of generation plants of different energy sources, transmission networks, and distribution lines. Each of these components can have environmental impacts at multiple stages of their development and use including in their construction, during the generation of electricity, and in their decommissioning and disposal. These impacts can be split into operational impacts and construction impacts. All forms of electricity generation have some form of environmental impact, but coal-fired power is the dirtiest. This page is organized by energy source and includes impacts such as water usage, emissions, local pollution, and wildlife displacement.

<span class="mw-page-title-main">Cogeneration</span> Simultaneous generation of electricity and useful heat

Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time.

<span class="mw-page-title-main">Waste-to-energy plant</span> Building that incinerates unusable garbage

A waste-to-energy plant is a waste management facility that combusts wastes to produce electricity. This type of power plant is sometimes called a trash-to-energy, municipal waste incineration, energy recovery, or resource recovery plant.

<span class="mw-page-title-main">Coal pollution mitigation</span>

Coal pollution mitigation, sometimes labeled as clean coal, is a series of systems and technologies that seek to mitigate health and environmental impact of burning coal for energy. Burning coal releases harmful substances that contribute to air pollution, acid rain, and greenhouse gas emissions. Mitigation includes precombustion approaches, such as cleaning coal, and post combustion approaches, include flue-gas desulfurization, selective catalytic reduction, electrostatic precipitators, and fly ash reduction. These measures aim to reduce coal's impact on human health and the environment.

<span class="mw-page-title-main">Thermal power station</span> Power plant that generates electricity from heat energy

A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a steam turbine connected to an electrical generator. The low-pressure exhaust from the turbine enters a steam condenser where it is cooled to produce hot condensate which is recycled to the heating process to generate more high pressure steam. This is known as a Rankine cycle.

An integrated gasification combined cycle (IGCC) is a technology using a high pressure gasifier to turn coal and other carbon based fuels into pressurized gas—synthesis gas (syngas). It can then remove impurities from the syngas prior to the electricity generation cycle. Some of these pollutants, such as sulfur, can be turned into re-usable byproducts through the Claus process. This results in lower emissions of sulfur dioxide, particulates, mercury, and in some cases carbon dioxide. With additional process equipment, a water-gas shift reaction can increase gasification efficiency and reduce carbon monoxide emissions by converting it to carbon dioxide. The resulting carbon dioxide from the shift reaction can be separated, compressed, and stored through sequestration. Excess heat from the primary combustion and syngas fired generation is then passed to a steam cycle, similar to a combined cycle gas turbine. This process results in improved thermodynamic efficiency, compared to conventional pulverized coal combustion.

<span class="mw-page-title-main">Waste-to-energy</span> Process of generating energy from the primary treatment of waste

Waste-to-energy (WtE) or energy-from-waste (EfW) is the process of generating energy in the form of electricity and/or heat from the primary treatment of waste, or the processing of waste into a fuel source. WtE is a form of energy recovery. Most WtE processes generate electricity and/or heat directly through combustion, or produce a combustible fuel commodity, such as methane, methanol, ethanol or synthetic fuels, often derived from the product syngas.

<span class="mw-page-title-main">Biomass heating system</span>

Biomass heating systems generate heat from biomass. The systems may use direct combustion, gasification, combined heat and power (CHP), anaerobic digestion or aerobic digestion to produce heat. Biomass heating may be fully automated or semi-automated they may be pellet-fired, or they may be combined heat and power systems.

<span class="mw-page-title-main">Coal-fired power station</span> Type of thermal power station

A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide there are over 2,400 coal-fired power stations, totaling over 2,130 gigawatts capacity. They generate about a third of the world's electricity, but cause many illnesses and the most early deaths, mainly from air pollution. World installed capacity doubled from 2000 to 2023 and increased 2% in 2023.

<span class="mw-page-title-main">Gas-fired power plant</span> One or more generators which convert natural gas into electricity

A gas-fired power plant, sometimes referred to as gas-fired power station, natural gas power plant, or methane gas power plant, is a thermal power station that burns natural gas to generate electricity. Gas-fired power plants generate almost a quarter of world electricity and are significant sources of greenhouse gas emissions. However, they can provide seasonal, dispatchable energy generation to compensate for variable renewable energy deficits, where hydropower or interconnectors are not available. In the early 2020s batteries became competitive with gas peaker plants.

<span class="mw-page-title-main">Biomass briquettes</span> Fuel source made from green waste

Biomass briquettes are a biofuel substitute made of biodegradable green waste with lower emissions of greenhouses gases and carbon dioxide then traditional fuel sources. This fuel source is used as an alternative for harmful biofuels. Briquettes are used for heating, cooking fuel, and electricity generation usually in developing countries that do not have access to more modern fuel sources. Biomass briquettes have become popular in developed countries due to the accessibility, and eco-friendly impact. The briquettes can be used in the developed countries for producing electricity from steam power by heating water in boilers.

Hydromethanation, [hahy-droh- meth-uh-ney-shuhn] is the process by which methane is produced through the combination of steam, carbonaceous solids and a catalyst in a fluidized bed reactor. The process, developed over the past 60 years by multiple research groups, enables the highly efficient conversion of coal, petroleum coke and biomass into clean, pipeline quality methane.

<span class="mw-page-title-main">Bioenergy with carbon capture and storage</span>

Bioenergy with carbon capture and storage (BECCS) is the process of extracting bioenergy from biomass and capturing and storing the carbon, thereby removing it from the atmosphere. BECCS can theoretically be a "negative emissions technology" (NET), although its deployment at the scale considered by many governments and industries can "also pose major economic, technological, and social feasibility challenges; threaten food security and human rights; and risk overstepping multiple planetary boundaries, with potentially irreversible consequences". The carbon in the biomass comes from the greenhouse gas carbon dioxide (CO2) which is extracted from the atmosphere by the biomass when it grows. Energy ("bioenergy") is extracted in useful forms (electricity, heat, biofuels, etc.) as the biomass is utilized through combustion, fermentation, pyrolysis or other conversion methods.

References

  1. ↑ "Yearly electricity data". ember-climate.org. 6 December 2023. Retrieved 23 December 2023.
  2. ↑ "Getting Wind and Sun onto the Grid" (PDF). International Energy Agency. Archived (PDF) from the original on 16 December 2018. Retrieved 9 May 2019.
  3. ↑ Heidari, N.; Pearce, J. M. (2016). "A Review of Greenhouse Gas Emission Liabilities as the Value of Renewable Energy for Mitigating Lawsuits for Climate Change Related Damages". Renewable and Sustainable Energy Reviews. 55: 899–908. doi:10.1016/j.rser.2015.11.025. S2CID   111165822.
  4. 1 2 "Why carbon capture could be the game-changer the world needs". World Economic Forum. Archived from the original on 9 May 2019. Retrieved 9 May 2019.
  5. 1 2 "We have too many fossil-fuel power plants to meet climate goals". Environment. 1 July 2019. Archived from the original on 3 July 2019. Retrieved 8 July 2019.
  6. ↑ "The West's Nuclear Mistake". MSN. Retrieved 8 December 2021.
  7. ↑ Sonal Patel (4 January 2017). "Who Has the World's Most Efficient Coal Power Plant Fleet?". Archived from the original on 23 June 2018. Retrieved 5 September 2018.
  8. ↑ "Electric Generation Efficiency: Working Document of the NPC Global Oil & Gas Study" (PDF). National Petroleum Council. 18 July 2007. p. 5. Archived from the original (PDF) on 4 July 2010. Retrieved 18 July 2007.
  9. ↑ Trivelpiece, Alvin (1993). "The Future of Nuclear Research Centers" (PDF). Oak Ridge National Laboratory Review. 26 (3 & 4): 28. Archived (PDF) from the original on 31 January 2017. Retrieved 23 February 2017.
  10. ↑ "Claverton-energy.co.uk". Archived from the original on 5 October 2011. Retrieved 25 August 2009.
  11. ↑ SEC Mohave Generation Station Archived 14 September 2008 at the Wayback Machine Retrieved 24-07-2008
  12. ↑ Fouladi Fard, Reza; Naddafi, K.; Yunesian, M.; Nabizadeh Nodehi, R.; et al. (2016). "The assessment of health impacts and external costs of natural gas-fired power plant of Qom". Environmental Science and Pollution Research. 23 (20): 20922–20936. Bibcode:2016ESPR...2320922F. doi:10.1007/s11356-016-7258-0. PMID   27488708. S2CID   25937869.
  13. 1 2 3 "Steam Electric Power Generating Effluent Guidelines – 2015 Final Rule". Washington, DC: US Environmental Protection Agency (EPA). 4 September 2020.
  14. ↑ Air pollution from electricity-generating large combustion plants, Copenhagen: European Environment Agency (EEA), 2008, ISBN   978-92-9167-355-1, archived from the original on 16 July 2011
  15. ↑ "The Phoenix Sun | Dirty numbers | The 200 Most Polluting Power Plants in the World". Archived from the original on 26 March 2014. Retrieved 17 September 2013.
  16. ↑ "Sources Climate Change". EPA. 2012. Archived from the original on 9 September 2012. Retrieved 26 August 2012.
  17. ↑ "Electricity Sector Emissions Climate Change". EPA. 2012. Archived from the original on 25 September 2012. Retrieved 26 August 2012.
  18. ↑ "US EPA Clean Energy—Coal". Archived from the original on 11 May 2010. Retrieved 21 October 2009.
  19. ↑ "US EPA Clean Energy—Oil". Archived from the original on 11 May 2010. Retrieved 21 October 2009.
  20. ↑ "US EPA Clean Energy—Gas". Archived from the original on 3 April 2009. Retrieved 21 October 2009.
  21. ↑ Solomon, S.; et al. (2007). "Summary for policymakers" (PDF). A report of Working Group I of the Intergovernmental Panel on Climate Change. IPCC. Archived (PDF) from the original on 7 May 2017. Retrieved 24 March 2010.
  22. ↑ "Estimating carbon dioxide emissions from coal plants". Global Energy Monitor . Retrieved 8 February 2020.
  23. ↑ "A methodology to constrain carbon dioxide emissions from coal-fired power plants using satellite observations of co-emitted nitrogen dioxide" (PDF). Atmospheric Chemistry and Physics.
  24. ↑ Committee on Benefits of DOE R&D on Energy Efficiency and Fossil Energy, US NRC (2001). Energy research at DOE: was it worth it? Energy efficiency and fossil energy research 1978 to 2000. National Academies Press. p. 174. ISBN   978-0-309-07448-3.
  25. 1 2 3 4 Nel, A. (6 May 2005). Air Pollution-Related Illness: Effects of Particles. Science, 308(5723), 804-806.
  26. 1 2 3 Grahame, T., & Schlesinger, R. (15 April 2007). Health Effects of Airborne Particulate Matter: Do We Know Enough to Consider Regulating Specific Particle Types or Sources?. Inhalation Toxicology, 19(6–7), 457–481.
  27. 1 2 3 Schobert, H. H. (2002). Energy and Society. New York: Taylor & Francis, 241–255.
  28. ↑ Freedman, Andrew (5 July 2011). "New study blames 10-year lull in global warming on China coal use, air pollution". The Washington Post. Archived from the original on 16 July 2017. Retrieved 29 October 2018.
  29. ↑ "Lowering Cost and Waste in Flue Gas Desulfurization Wastewater Treatment". Power Mag. Electric Power. March 2017. Archived from the original on 7 April 2017. Retrieved 6 April 2017.
  30. 1 2 3 Coal Combustion: Nuclear Resource or Danger? Archived 5 February 2007 at the Wayback Machine by Alex Gabbard, ORNL Review, Summer/Fall 1993, Vol. 26, Nos. 3 and 4.
  31. ↑ Thompson, Linda. "Vitrification of Nuclear Waste". PH240 – Fall 2010: Introduction to the Physics of Energy. Stanford University. Archived from the original on 18 October 2015. Retrieved 10 August 2014.
  32. ↑ Physics.ohio-state.edu Archived 27 March 2009 at the Wayback Machine
  33. ↑ "Fukushima radioactive fallout nears Chernobyl levels". New Scientist. Archived from the original on 26 March 2011. Retrieved 24 April 2011.
  34. 1 2 "Study of Coal Ash Sites Finds Extensive Water Contamination" Archived 29 August 2010 at the Wayback Machine McClatchy; also archived at: commondreams.org Archived 28 August 2010 at the Wayback Machine
  35. 1 2 EarthJustice news release, 2010 Sept. 16, "New Report—Coal Ash Linked To Cancer and Other Maladies; Coal's Waste Is Poisoning Communities in 34 States" Archived 19 September 2010 at the Wayback Machine Earthjustice.org and Physicians for Social Responsibility, "Coal Ash: The Toxic Threat to Our Communities and Our Environment" Archived 6 October 2010 at the Wayback Machine 2010 September 16, earthjustice.org
  36. ↑ nytimes.com "Mercury Found in Every Fish Tested, Scientists Say" Archived 29 December 2016 at the Wayback Machine The New York Times, 2009 Aug. 19
  37. ↑ "Coal to biomass power plant conversion" (PDF). Archived from the original (PDF) on 6 March 2017. Retrieved 31 July 2019.
  38. ↑ "Coal to biomass conversion by Georgia Power". Archived from the original on 3 December 2010. Retrieved 26 April 2009.
  39. ↑ Conversion of coal to waste-fired power plant Archived 21 July 2009 at the Wayback Machine
  40. ↑ "MHPS Will Convert Dutch CCGT to Run on Hydrogen". May 2018. Archived from the original on 3 May 2019. Retrieved 3 May 2019.
  41. ↑ "Torrefaction of biomass sometimes needed when using biomass in converted FFPS". Archived from the original on 29 November 2014. Retrieved 24 November 2014.
  42. ↑ Siemens Gamesa ETES-switch solution
  43. ↑ AustralianCoal.com.au Archived 7 December 2007 at the Wayback Machine —Clean Coal Overview
  44. ↑ Hansen, James (2009). Storms of My Grandchildren. London: Bloomsbury Publishing. p. 242. ISBN   978-1-4088-0745-3.
  45. ↑ "The plan to convert the North to run on hydrogen". Utility Week. 30 November 2018. Archived from the original on 9 May 2019. Retrieved 9 May 2019.
  46. ↑ "H-vision: blue hydrogen for a green future". Gas World. Archived from the original on 9 May 2019. Retrieved 9 May 2019.
  47. ↑ Natural gas to hydrogen: Natural gas reforming
  48. ↑ KITT/IASS – Producing CO2 free hydrogen from natural gas for energy usage
  49. ↑ The reaction that would give us clean fossil fuels forever
  50. ↑ Hydrogen from methane without CO2 emissions
  51. ↑ The Full Cost of Electricity (PDF). University of Texas at Austin. April 2018. p. 11. Archived (PDF) from the original on 10 May 2019. Retrieved 10 May 2019.

Bibliography

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.