Fossil fuel power station
A fossil fuel power station is a
Fossil fuel power stations provide most of the
By-products of fossil fuel power plant operation must be considered in their design and operation.
Fossil fueled power stations are major emitters of
Basic concepts: heat into mechanical energy
In a fossil fuel power plant the chemical energy stored in fossil fuels such as
The
Typical
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
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
One type of fossil fuel power plant uses a
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
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
Natural gas
Gas is a very common fuel and has mostly
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
Environmental impacts
Thermal power plants are one of the main artificial sources of producing toxic gases and
Acid rain is caused by the emission of
In 2008, the European Environment Agency (EEA) documented fuel-dependent emission factors based on actual emissions from power plants in the European Union.[14]
Pollutant | Hard coal | Brown coal | Fuel oil | Other oil | Gas |
---|---|---|---|---|---|
CO2 (g/GJ) | 94,600 | 101,000 | 77,400 | 74,100 | 56,100 |
SO2 (g/GJ) | 765 | 1,361 | 1,350 | 228 | 0.68 |
NOx (g/GJ) | 292 | 183 | 195 | 129 | 93.3 |
CO (g/GJ) | 89.1 | 89.1 | 15.7 | 15.7 | 14.5 |
Non methane organic compounds (g/GJ) | 4.92 | 7.78 | 3.70 | 3.24 | 1.58 |
Particulate matter (g/GJ) | 1,203 | 3,254 | 16 | 1.91 | 0.1 |
Flue gas volume total (m3/GJ) | 360 | 444 | 279 | 276 | 272 |
Carbon dioxide
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.
The Intergovernmental Panel on Climate Change (
Emissions can be reduced with higher combustion temperatures, yielding more efficient production of electricity within the cycle. As of 2019[update] 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 =
where "capacity" is the "
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
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
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:
- a baghouse
- an electrostatic precipitator (ESP)
- 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
Fossil-fuel power stations, particularly coal-fired plants, are a major source of
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
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
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
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
Phase out of fossil fuel power plants
As of 2019[update] 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
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:
- Capital costs, including waste disposal and decommissioning costs for nuclear energy.
- Operating and maintenance costs.
- Fuel costs for fossil fuel and biomass sources, and which may be negative for wastes.
- Likely annual hours per year run or load factor, which may be as low as 30% for wind energy, or as high as 90% for nuclear energy.
- Offset sales of heat, for example in combined heat and power district heating (CHP/DH).
These costs occur over the 30–50 year life[clarification needed] of the fossil fuel power plants, using discounted cash flows.
See also
- Biomass
- Biomass power station
- Boiler (power generation)
- Coal analyzer
- Coal mining
- Combined heat and power
- Cooling tower system
- Environmental impact of the coal industry
- Flue gas stacks
- Fossil fuel phase-out
- Geothermal power
- Global Energy Monitor
- Global warming
- Greenhouse gas
- List of coal power stations
- List of thermal power station failures
- Mercury vapor turbine
- Natural gas
- Power station
- Relative cost of electricity generated by different sources
- Renewable energy power station
- Steam reforming
- Steam turbine
- Thermal power station
- Water-tube boiler
References
- ^ "Yearly electricity data". ember-climate.org. 6 December 2023. Retrieved 23 December 2023.
- ^ "Getting Wind and Sun onto the Grid" (PDF). International Energy Agency. Archived (PDF) from the original on 16 December 2018. Retrieved 9 May 2019.
- S2CID 111165822.
- ^ a b "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.
- ^ a b "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.
- ^ "The West's Nuclear Mistake". MSN. Retrieved 8 December 2021.
- ^ 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.
- ^ "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.
- ^ 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.
- ^ "Claverton-energy.co.uk". Archived from the original on 5 October 2011. Retrieved 25 August 2009.
- ^ SEC Mohave Generation Station Archived 14 September 2008 at the Wayback Machine Retrieved 24-07-2008
- S2CID 25937869.
- ^ a b c "Steam Electric Power Generating Effluent Guidelines – 2015 Final Rule". Washington, DC: US Environmental Protection Agency (EPA). 4 September 2020.
- ISBN 978-92-9167-355-1, archivedfrom the original on 16 July 2011
- ^ "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.
- ^ "Sources Climate Change". EPA. 2012. Archived from the original on 9 September 2012. Retrieved 26 August 2012.
- ^ "Electricity Sector Emissions Climate Change". EPA. 2012. Archived from the original on 25 September 2012. Retrieved 26 August 2012.
- ^ "US EPA Clean Energy—Coal". Archived from the original on 11 May 2010. Retrieved 21 October 2009.
- ^ "US EPA Clean Energy—Oil". Archived from the original on 11 May 2010. Retrieved 21 October 2009.
- ^ "US EPA Clean Energy—Gas". Archived from the original on 3 April 2009. Retrieved 21 October 2009.
- ^ 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.
- ^ "Estimating carbon dioxide emissions from coal plants". Global Energy Monitor. Retrieved 8 February 2020.
- ^ "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.
- ISBN 978-0-309-07448-3.
- ^ a b c d Nel, A. (6 May 2005). Air Pollution-Related Illness: Effects of Particles. Science, 308(5723), 804-806.
- ^ a b c 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.
- ^ a b c Schobert, H. H. (2002). Energy and Society. New York: Taylor & Francis, 241–255.
- ^ 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.
- ^ "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.
- ^ ORNLReview, Summer/Fall 1993, Vol. 26, Nos. 3 and 4.
- ^ 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.
- ^ Physics.ohio-state.edu Archived 27 March 2009 at the Wayback Machine
- ^ "Fukushima radioactive fallout nears Chernobyl levels". New Scientist. Archived from the original on 26 March 2011. Retrieved 24 April 2011.
- ^ a b "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
- ^ a b 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
- ^ 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
- ^ "Coal to biomass power plant conversion" (PDF). Archived from the original (PDF) on 6 March 2017. Retrieved 31 July 2019.
- ^ "Coal to biomass conversion by Georgia Power". Archived from the original on 3 December 2010. Retrieved 26 April 2009.
- ^ Conversion of coal to waste-fired power plant Archived 21 July 2009 at the Wayback Machine
- ^ "MHPS Will Convert Dutch CCGT to Run on Hydrogen". May 2018. Archived from the original on 3 May 2019. Retrieved 3 May 2019.
- ^ "Torrefaction of biomass sometimes needed when using biomass in converted FFPS". Archived from the original on 29 November 2014. Retrieved 24 November 2014.
- ^ Siemens Gamesa ETES-switch solution
- ^ AustralianCoal.com.au Archived 7 December 2007 at the Wayback Machine—Clean Coal Overview
- ISBN 978-1-4088-0745-3.
- ^ "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.
- ^ "H-vision: blue hydrogen for a green future". Gas World. Archived from the original on 9 May 2019. Retrieved 9 May 2019.
- ^ Natural gas to hydrogen: Natural gas reforming
- ^ KITT/IASS – Producing CO2 free hydrogen from natural gas for energy usage
- ^ The reaction that would give us clean fossil fuels forever
- ^ Hydrogen from methane without CO2 emissions
- ^ 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
- Steam: Its Generation and Use (2005). 41st edition, Babcock & Wilcox Company, ISBN 0-9634570-0-4
- Steam Plant Operation (2011). 9th edition, Everett B. Woodruff, Herbert B. Lammers, Thomas F. Lammers (coauthors), ISBN 978-0-07-166796-8
- Power Generation Handbook: Fundamentals of Low-Emission, High-Efficiency Power Plant Operation (2012). 2nd edition. Philip Kiameh, McGraw-Hill Professional, ISBN 978-0-07-177227-3
- Standard Handbook of Powerplant Engineering (1997). 2nd edition, Thomas C. Elliott, Kao Chen, Robert Swanekamp (coauthors), McGraw-Hill Professional, ISBN 0-07-019435-1
External links
- Conventional coal-fired power plant
- Large industrial cooling towers
- Coal Power more deadly than Nuclear
- "Must We Suffer Smoke" , May 1949, Popular Science article on early methods of scrubbing emissions from coal-fired power plants
- Gas Power Plant News from Power Engineering Magazine Archived 10 July 2015 at the Wayback Machine