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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.

The combustion of coal releases diverse chemicals into the air. The main products are water and carbon dioxide, just like the combustion of petroleum. Also released are sulfur dioxide and nitrogen oxides, as well as some mercury. The residue remaining after combustion, coal ash often contains arsenic, mercury, and lead. Finally, the burning of coal, especially anthracite, can release radioactive materials.^[1]

Mitigation technologies

Mitigation of coal-based pollution can be divided into several distinct approaches. Coal pollution mitigation seek to minimize negative impacts of coal combustion.^[2]

Precombustion

Prior to its combustion, coal can be cleaned by physical and by chemical means.

Physical cleaning of coal usually involves gravimetric processes, often in conjunction with froth flotation Such processes remove minerals and other noncombustible components of coal, exploiting their greater density vs that of coal. This technology is widely practiced.

Coal can also be cleaned in part by chemical treatments. The concept is to use chemicals to remove deleterious components of coal, leaving the combustible material behind. Typically, coal cleaning entails treatment of crushed coal with acids or bases. This technology is expensive and has rarely moved beyond the demonstration phase. During World War II, German industry removed ash from coal by treatments with hydrofluoric acid and related reagents.^[2]

Post-combustion

The wastes produced by the combustion of coal can be classified into three categories: gases, particulates, and solids (ash). The gaseous products can be filtered and scrubbed to miminize the release of SO_x, NO_x, mercury:

SO₂ can be removed by flue-gas desulfurization
NO₂ can be removed by selective catalytic reduction (SCR).
Mercury emissions can be reduced by up to 95%.^[3]

Electrostatic precipitators remove particulates. Wet scrubbers can remove both gases and particulates.

Ash

The solid residue, coal ash, requires separate set of technologies but usually involves landfilling or some immobilization approaches. Reducing fly ash reduces emissions of radioactive materials.

Carbon capture

Several different technological methods are available for carbon capture:

Pre-combustion capture – This involves the gasification of a feedstock (such as coal) to form synthesis gas, which may be shifted to produce an H₂ and CO₂-rich gas mixture, from which the CO₂ can be efficiently captured and separated, transported, and ultimately sequestered,^[4] This technology is usually associated with Integrated Gasification Combined Cycle process configurations.^[5]
Post-combustion capture – This refers to capture of CO₂ from exhaust gases of combustion processes.
Oxy-fuel combustion – Fossil fuels such as coal are burned in a mixture of recirculated flue gas and oxygen, rather than in air, which largely eliminates nitrogen from the flue gas enabling efficient, low-cost CO₂ capture.^[6]

Satellite monitoring

Satellite monitoring is now used to crosscheck national data, for example Sentinel-5 Precursor has shown that Chinese control of SO₂ has only been partially successful.^[7] It has also revealed that low use of technology such as SCR has resulted in high NO₂ emissions in South Africa and India.^[8]

Combined cycle power plants

A few Integrated gasification combined cycle (IGCC) coal-fired power plants have been built with coal gasification. Although they burn coal more efficiently and therefore emit less pollution, the technology has not generally proved economically viable for coal, except possibly in Japan although this is controversial.^[9]^[10]

Case studies

In conjunction with enhanced oil recovery and other applications, commercial-scale CCS is currently being tested in several countries.^{[by whom?]} Proposed CCS sites are subjected to extensive investigation and monitoring to avoid potential hazards, which could include leakage of sequestered CO2 to the atmosphere, induced geological instability, or contamination of water sources such as oceans and aquifers used for drinking water supplies. As of 2021, the only demonstrator for CCS on a coal plant that stores the gas underground is part of the Boundary Dam Power Station.^{[citation needed]}

The Great Plains Synfuels plant supports the technical feasibility of carbon dioxide sequestration. Carbon dioxide from the coal gasification is shipped to Canada, where it is injected into the ground to aid in oil recovery. A drawback of the carbon sequestration process is that it is expensive compared to traditional processes.

The Kemper County IGCC Project, a proposed 582 MW coal gasification-based power plant, was expected to use pre-combustion capture of CO₂ to capture 65% of the CO₂ the plant produces, which would have been utilized and geologically sequestered in enhanced oil recovery operations.^[11] However, after many delays and a cost runup to $7.5 billion (triple the initial budget),^[12] the coal gasification project was abandoned and as of late 2017, Kemper is under construction as a cheaper natural gas power plant.^[13]

The Saskatchewan Government's Boundary Dam Integrated Carbon Capture and Sequestration Demonstration Project will use post-combustion, amine-based scrubber technology to capture 90% of the CO₂ emitted by Unit 3 of the power plant; this CO₂ will be pipelined to and utilized for enhanced oil recovery in the Weyburn oil fields.^[14]

An early example of a coal-based plant using (oxy-fuel) carbon-capture technology is Swedish company Vattenfall’s Schwarze Pumpe power station located in Spremberg, Germany, built by German firm Siemens, which went on-line in September 2008.^[15]^[16] The facility captures CO₂ and acid rain producing pollutants, separates them, and compresses the CO₂ into a liquid. Plans are to inject the CO₂ into depleted natural gas fields or other geological formations. Vattenfall opines that this technology is considered not to be a final solution for CO₂ reduction in the atmosphere, but provides an achievable solution in the near term while more desirable alternative solutions to power generation can be made economically practical.^[16]

Other examples of oxy-combustion carbon capture are in progress. Callide Power Station has retrofitted a 30-MWth existing PC-fired power plant to operate in oxy-fuel mode; in Ciuden, Spain, Endesa has a newly built 30-MWth oxy-fuel plant using circulating fluidized bed combustion (CFBC) technology.^[17] Babcock-ThermoEnergy's Zero Emission Boiler System (ZEBS) is oxy-combustion-based; this system features near 100% carbon-capture and according to company information virtually no air-emissions.^[18]

Other carbon capture and storage technologies include those that dewater low-rank coals. Low-rank coals often contain a higher level of moisture content which contains a lower energy content per tonne. This causes a reduced burning efficiency and an increased emissions output. Reduction of moisture from the coal prior to combustion can reduce emissions by up to 50 percent.^[19]^{[citation needed]}

In the late 1980s and early 1990s, the U.S. Department of Energy (DOE) conducted projects called the Clean Coal Technology & Clean Coal Power Initiative (CCPI).^[20]^[21]

Financial impact

Whether carbon capture and storage technology is adopted worldwide will "...depend less on science than on economics. Cleaning coal is very expensive."^[22]

Cost of converting a single coal-fired power plant

Conversion of a conventional coal-fired power plant is done by injecting the CO₂ into ammonium carbonate after which it is then transported and deposited underground (preferably in soil beneath the sea).^[23] This injection process however is by far the most expensive. Besides the cost of the equipment and the ammonium carbonate, the coal-fired power plant also needs to use 30% of its generated heat to do the injection (parasitic load). A test-setup has been done in the American Electric Power Mountaineer coal-burning power plant.

One solution to reduce this thermal loss/parasitic load is to burn the pulverised load with pure oxygen instead of air.^[23]

Cost implications for new coal-fired power plants

Newly built coal-fired power plants can be made to immediately use gasification of the coal prior to combustion. This makes it much easier to separate off the CO₂ from the exhaust fumes, making the process cheaper. This gasification process is done in new coal-burning power plants such as the coal-burning power plant at Tianjin, called "GreenGen".

Country by country experiences

Local pollution standards include GB13223-2011 (China), India,^[24] the Industrial Emissions Directive (EU) and the Clean Air Act (United States).

China

Since 2006, China releases more CO₂ than any other country.^[25]^[26]^[27]^[28]^[29] Researchers in China are focusing on increasing efficiency of burning coal so they can get more power out of less coal.^[30] It is estimated that new high efficiency power plants could reduce CO₂ emission by 7% because they won't have to burn as much coal to get the same amount of power.^[30]

As of 2019^[update] costs of retrofitting CCS are unclear and the economics depends partly on how the Chinese national carbon trading scheme progresses.^[31]

India

Pollution led to more than 2.3 million premature deaths in India in 2019, according to a new Lancet study. Nearly 1.6 million deaths were due to air pollution alone, and more than 500,000 were caused by water pollution. India has developed instruments and regulatory powers to mitigate pollution sources but there is no centralized system to drive pollution control efforts and achieve substantial improvements," the study said adding that in 93% of the country, the amount of pollution remains well above the World Health Organization (WHO) guidelines.^[32]

Canada

In 2014 SaskPower a provincial-owned electric utility finished renovations on Boundary Dam's boiler number 3 making it the world's first post-combustion carbon capture storage facility.^[33] The renovation project ended up costing a little over $1.2 billion and can scrub out CO₂ and toxins from up to 90 percent of the flue gas that it emits.^[33]

Japan

Following the catastrophic failure of the Fukushima I Nuclear Power Plant in Japan that resulted from the 2011 Tōhoku earthquake and tsunami, and the subsequent widespread public opposition against nuclear power, high energy, lower emission (HELE) coal power plants were increasingly favored by the Shinzō Abe-led government to recoup lost energy capacity from the partial shutdown of nuclear power plants in Japan and to replace aging coal and oil-fired power plants, while meeting 2030 emission targets of the Paris Agreement. 45 HELE power plants have been planned, purportedly to employ integrated gasification fuel cell cycle, a further development of integrated gasification combined cycle.^[34]^[35]

Japan had adopted prior pilot projects on IGCC coal power plants in the early-1990s and late-2000s.

U.S.

In the United States, clean coal was mentioned by former President George W. Bush on several occasions, including his 2007 State of the Union Address. Bush's position was that carbon capture and storage technologies should be encouraged as one means to reduce the country's dependence on foreign oil.

During the US Presidential campaign for 2008, both candidates John McCain and Barack Obama expressed interest in the development of CCS technologies as part of an overall comprehensive energy plan. The development of pollution mitigation technologies could also create export business for the United States or any other country working on it.

The American Reinvestment and Recovery Act allocated $3.4 billion for advanced carbon capture and storage technologies, including demonstration projects.

Former Secretary of State Hillary Clinton has said that "we should strive to have new electricity generation come from other sources, such as clean coal and renewables", and former Energy Secretary Dr. Steven Chu has said that "It is absolutely worthwhile to invest in carbon capture and storage", noting that even if the U.S. and Europe turned their backs on coal, developing nations like India and China would likely not.

During the first 2012 United States presidential election debate, Mitt Romney expressed his support for clean coal, and claimed that current federal policies were hampering the coal industry.^[36]

During the Trump administration, an Office of Clean Coal and Carbon Management was set up within the United States Department of Energy, but was abolished in the Biden administration.

References

^ Hower, James (2016). "Coal". Kirk-Othmer Encyclopedia of Chemical Technology. pp. 1–63. doi:10.1002/0471238961.0315011222151818.a01.pub3. ISBN 978-0-471-48494-3.
^ ^a ^b Chiang, Shiao-Hung; Cobb, James T. (2000). "Coal Conversion Processes, Cleaning and Desulfurization". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.0312050103080901.a01. ISBN 978-0-471-48494-3.
^ "Mercury control from coal combustion". UNEP. Archived from the original on August 17, 2018.
^ "Pre-combustion Carbon Capture Research". Energy.gov. Office of Fossil Energy, U.S. Department of Energy. Retrieved 22 July 2014.
^ "Picking a Winner in Clean-Coal Technology".
^ "R&D Facts - Oxy-Fuel Combustion" (PDF). National Energy Technology Laboratory, U.S. Department of Energy. Archived from the original (PDF) on 31 October 2014. Retrieved 22 July 2014.
^ Karplus, Valerie J.; Zhang, Shuang; Almond, Douglas (2018). "Quantifying coal power plant responses to tighter SO₂ emissions standards in China". Proceedings of the National Academy of Sciences. 115 (27): 7004–09. Bibcode:2018PNAS..115.7004K. doi:10.1073/pnas.1800605115. PMC 6142229. PMID 29915085.
^ "New satellite data analysis reveals world's biggest NO₂ emissions hotspots". Greenpeace International.
^ "Universal failure: How IGCC coal plants waste money and emissions Nove" (PDF). Kiko Network. Archived (PDF) from the original on 2016-12-19. Retrieved 13 November 2018.
^ "Japan says no to high-emission coal power plants". Nikkei Asian Review. 26 July 2018.
^ "IGCC Project Examples - Kemper County IGCC Project". Gasifipedia. National Energy Technology Laboratory, U.S. Department of Energy. Archived from the original on 17 March 2014. Retrieved 22 July 2014.
^ Urbina, Ian (2016-07-05). "Piles of Dirty Secrets Behind a Model 'Clean Coal' Project (Published 2016)". The New York Times. ISSN 0362-4331. Retrieved 2021-02-03.
^ Geuss, Megan (2017-06-29). "$7.5 billion Kemper power plant suspends coal gasification". Ars Technica. Retrieved 2017-07-01.
^ "Boundary Dam Integrated Carbon Capture and Sequestration Demonstration Project". Global CCS Institute. Archived from the original on 10 August 2014. Retrieved 22 July 2014.
^ "Vattenfall's Project on CSS". Vattenfall. Archived from the original on 2010-10-26.
^ ^a ^b http://discovermagazine.com/2009/feb/25-can-clean-coal-actually-work/?searchterm=clean%20coal "Can Clean Coal Actually Work?" article in Feb. 2009 issue, p. 18, Retrieved 2009-05-11
^ "Overview of Oxy-fuel Combustion Technology for CO₂ Capture". Cornerstone Magazine. World Coal Association. Retrieved 22 July 2014.
^ [leads nowhere previously cited - http://ww25.thermoenergy.com/Zm9yY2VTUg]
^ Ge, Lichao; Zhang, Yanwei; Xu, Chang; Wang, Zhihua; Zhou, Junhu; Cen, Kefa (2015-11-05). "Influence of the hydrothermal dewatering on the combustion characteristics of Chinese low-rank coals". Applied Thermal Engineering. 90: 174–181. Bibcode:2015AppTE..90..174G. doi:10.1016/j.applthermaleng.2015.07.015. ISSN 1359-4311.
^ "Clean Coal Technology & The Clean Coal Power Initiative". U.S. Department of Energy.
^ "Major Demonstrations: Clean Coal Power Initiative (CCPI)". NETL. Archived from the original on September 24, 2006. Retrieved 1 May 2012.
^ Ball, Jeffrey (2009-03-20). "Coal Hard Facts: Cleaning It Won't Be Dirt Cheap". The Wall Street Journal.
^ ^a ^b Nijhuis, Michelle (April 2014). "Can Coal Ever Be Clean?". National Geographic. Archived from the original on March 16, 2014.
^ Sugathan, Anish; Bhangale, Ritesh; Kansal, Vishal; Hulke, Unmil (2018). "How can Indian power plants cost-effectively meet the new sulfur emission standards? Policy evaluation using marginal abatement cost-curves". Energy Policy. 121: 124–37. Bibcode:2018EnPol.121..124S. doi:10.1016/j.enpol.2018.06.008. S2CID 158703760.
^ "China's Emissions: More Than U.S. Plus Europe, and Still Rising". The New York Times. 2018-01-25.
^ "Chinese coal fuels rise in global carbon emissions". The Times. 2017-11-14.
^ "Yes, The U.S. Leads All Countries In Reducing Carbon Emissions". Forbes. 2017-10-24.
^ "World carbon dioxide emissions data by country: China speeds ahead of the rest". The Guardian. 2011-01-31.
^ "China now no. 1 in CO₂ emissions; USA in second position". PBL Netherlands Environmental Assessment Agency. 19 June 2007. Archived from the original on 2019-07-09. Retrieved 2018-03-20.
^ ^a ^b "China's drive to clean up its coal power, one plant at a time". New Scientist. Retrieved 2017-05-04.
^ "Carbon Capture, Storage and Utilization to the Rescue of Coal? Global Perspectives and Focus on China and the United States". www.ifri.org. Retrieved 2020-01-25.
^ "Carbon capture and coal gasification can be a game changer for India - Opinion by Atanu Mukherjee | ET EnergyWorld". ETEnergyworld.com. Retrieved 2020-01-25.
^ ^a ^b Danko, Pete (2014-10-02). "World's First Full-Scale 'Clean' Coal Plant Opens in Canada". National Geographic Society. Archived from the original on January 12, 2019. Retrieved 2017-04-27.
^ McHugh, Babs (2017-02-23). "Japanese government planning to build 45 new coal fired power stations to diversify supply". ABC Online. Retrieved 2017-02-23.
^ Watanabe, Chisaki (2015-11-10). "Want to Burn Coal and Save the Planet? Japan Touts a Solution". Bloomberg. Retrieved 2017-02-23.
^ "Transcript And Audio: First Obama-Romney Debate". NPR. Federal News Service. 2012-10-03. Retrieved 2013-05-24.

External links

"International Energy Agency - Clean Coal Centre".
"National Energy Technology Laboratory compendium homepage". Archived from the original on 2008-08-29.
"Institute for Clean & Secure Energy". Archived from the original on 2009-03-02.
"US federal Office of Clean Coal and Carbon Management".
"Clean Coal Technology & The Clean Coal Power Initiative". US Department of Energy. Retrieved 2009-03-29.
"Clean Coal Technology Compendium". National Energy Technology Laboratory. Archived from the original on 2008-08-29. Retrieved 2009-03-29.
"Utah Clean Coal Program". University of Utah. Archived from the original on 2009-03-02. Retrieved 2009-03-29.
"Institute for Clean & Secure Energy". University of Utah. Archived from the original on 2009-03-02. Retrieved 2009-03-29.

[1] Hower, James (2016). "Coal". Kirk-Othmer Encyclopedia of Chemical Technology. pp. 1–63. doi:10.1002/0471238961.0315011222151818.a01.pub3. ISBN 978-0-471-48494-3.

[KO2-2] Chiang, Shiao-Hung; Cobb, James T. (2000). "Coal Conversion Processes, Cleaning and Desulfurization". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.0312050103080901.a01. ISBN 978-0-471-48494-3.

[:0-3] "Mercury control from coal combustion". UNEP. Archived from the original on August 17, 2018.

[4] "Pre-combustion Carbon Capture Research". Energy.gov. Office of Fossil Energy, U.S. Department of Energy. Retrieved 22 July 2014.

[5] "Picking a Winner in Clean-Coal Technology".

[6] "R&D Facts - Oxy-Fuel Combustion" (PDF). National Energy Technology Laboratory, U.S. Department of Energy. Archived from the original (PDF) on 31 October 2014. Retrieved 22 July 2014.

[7] Karplus, Valerie J.; Zhang, Shuang; Almond, Douglas (2018). "Quantifying coal power plant responses to tighter SO₂ emissions standards in China". Proceedings of the National Academy of Sciences. 115 (27): 7004–09. Bibcode:2018PNAS..115.7004K. doi:10.1073/pnas.1800605115. PMC 6142229. PMID 29915085.

[8] "New satellite data analysis reveals world's biggest NO₂ emissions hotspots". Greenpeace International.

[9] "Universal failure: How IGCC coal plants waste money and emissions Nove" (PDF). Kiko Network. Archived (PDF) from the original on 2016-12-19. Retrieved 13 November 2018.

[10] "Japan says no to high-emission coal power plants". Nikkei Asian Review. 26 July 2018.

[11] "IGCC Project Examples - Kemper County IGCC Project". Gasifipedia. National Energy Technology Laboratory, U.S. Department of Energy. Archived from the original on 17 March 2014. Retrieved 22 July 2014.

[12] Urbina, Ian (2016-07-05). "Piles of Dirty Secrets Behind a Model 'Clean Coal' Project (Published 2016)". The New York Times. ISSN 0362-4331. Retrieved 2021-02-03.

[ars_nat_gas_2017-13] Geuss, Megan (2017-06-29). "$7.5 billion Kemper power plant suspends coal gasification". Ars Technica. Retrieved 2017-07-01.

[14] "Boundary Dam Integrated Carbon Capture and Sequestration Demonstration Project". Global CCS Institute. Archived from the original on 10 August 2014. Retrieved 22 July 2014.

[15] "Vattenfall's Project on CSS". Vattenfall. Archived from the original on 2010-10-26.

[discovermagazine-16] ttps://discovermagazine.com/2009/feb/25-can-clean-coal-actually-work/?searchterm=clean%20coal "Can Clean Coal Actually Work?" article in Feb. 2009 issue, p. 18, Retrieved 2009-05-11

[17] "Overview of Oxy-fuel Combustion Technology for CO₂ Capture". Cornerstone Magazine. World Coal Association. Retrieved 22 July 2014.

[18] [leads nowhere previously cited - http://ww25.thermoenergy.com/Zm9yY2VTUg]

[19] Ge, Lichao; Zhang, Yanwei; Xu, Chang; Wang, Zhihua; Zhou, Junhu; Cen, Kefa (2015-11-05). "Influence of the hydrothermal dewatering on the combustion characteristics of Chinese low-rank coals". Applied Thermal Engineering. 90: 174–181. Bibcode:2015AppTE..90..174G. doi:10.1016/j.applthermaleng.2015.07.015. ISSN 1359-4311.

[20] "Clean Coal Technology & The Clean Coal Power Initiative". U.S. Department of Energy.

[21] "Major Demonstrations: Clean Coal Power Initiative (CCPI)". NETL. Archived from the original on September 24, 2006. Retrieved 1 May 2012.

[22] Ball, Jeffrey (2009-03-20). "Coal Hard Facts: Cleaning It Won't Be Dirt Cheap". The Wall Street Journal.

[Can_coal_ever_be_clean-23] Nijhuis, Michelle (April 2014). "Can Coal Ever Be Clean?". National Geographic. Archived from the original on March 16, 2014.

[24] Sugathan, Anish; Bhangale, Ritesh; Kansal, Vishal; Hulke, Unmil (2018). "How can Indian power plants cost-effectively meet the new sulfur emission standards? Policy evaluation using marginal abatement cost-curves". Energy Policy. 121: 124–37. Bibcode:2018EnPol.121..124S. doi:10.1016/j.enpol.2018.06.008. S2CID 158703760.

[25] "China's Emissions: More Than U.S. Plus Europe, and Still Rising". The New York Times. 2018-01-25.

[26] "Chinese coal fuels rise in global carbon emissions". The Times. 2017-11-14.

[27] "Yes, The U.S. Leads All Countries In Reducing Carbon Emissions". Forbes. 2017-10-24.

[28] "World carbon dioxide emissions data by country: China speeds ahead of the rest". The Guardian. 2011-01-31.

[29] "China now no. 1 in CO₂ emissions; USA in second position". PBL Netherlands Environmental Assessment Agency. 19 June 2007. Archived from the original on 2019-07-09. Retrieved 2018-03-20.

[:2-30] "China's drive to clean up its coal power, one plant at a time". New Scientist. Retrieved 2017-05-04.

[31] "Carbon Capture, Storage and Utilization to the Rescue of Coal? Global Perspectives and Focus on China and the United States". www.ifri.org. Retrieved 2020-01-25.

[32] "Carbon capture and coal gasification can be a game changer for India - Opinion by Atanu Mukherjee | ET EnergyWorld". ETEnergyworld.com. Retrieved 2020-01-25.

[:1-33] Danko, Pete (2014-10-02). "World's First Full-Scale 'Clean' Coal Plant Opens in Canada". National Geographic Society. Archived from the original on January 12, 2019. Retrieved 2017-04-27.

[34] McHugh, Babs (2017-02-23). "Japanese government planning to build 45 new coal fired power stations to diversify supply". ABC Online. Retrieved 2017-02-23.

[35] Watanabe, Chisaki (2015-11-10). "Want to Burn Coal and Save the Planet? Japan Touts a Solution". Bloomberg. Retrieved 2017-02-23.

[npr2012-10-03-36] "Transcript And Audio: First Obama-Romney Debate". NPR. Federal News Service. 2012-10-03. Retrieved 2013-05-24.

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v t e Environmental technology
General	Appropriate technology Clean technology Climate smart agriculture Environmental design Environmental impact assessment Eco-innovation Ecotechnology Electric vehicle Energy recycling Environmental Design Environmental impact assessment Environmental impact design Green building Green vehicle Environmentally healthy community design Public interest design Sustainability Sustainability science Sustainable (agriculture architecture design development food systems industries procurement refurbishment technology transport)
Pollution	Air pollution (control dispersion modeling) Industrial ecology Solid waste treatment Waste management Water (agricultural wastewater treatment industrial wastewater treatment sewage treatment waste-water treatment technologies water purification)
Sustainable energy	Efficient energy use Electrification Energy development Energy recovery Fuel (alternative fuel biofuel carbon-neutral fuel hydrogen technologies) List of energy storage projects Renewable energy commercialization transition Sustainable lighting Transportation (electric vehicle hybrid vehicle)
Conservation	Building (green insulation natural sustainable architecture New Urbanism New Classical) Conservation biology Ecoforestry Efficient energy use Energy conservation Energy recovery Energy recycling Environmental movement Environmental remediation Glass in green buildings Green computing Heat recovery ventilation High-performance buildings Land rehabilitation Nature conservation Permaculture Recycling Water heat recycling

v t e Coal
Coal types by grade (lowest to highest)	Xylit Peat¹ Lignite Sub-bituminous coal Bituminous coal Anthracite Graphite¹
Coal combustion	Ash pond Asian brown cloud Asthma Black coal equivalent Char Charcoal Coal combustion products fired power station gas phase-out pollution mitigation power in China power in the United States preparation plant seam fire tar Coke Coking Energy value Flue gas Fly ash Fossil fuel Fossil fuel phase-out Great Smog of London Greenhouse gas emissions Metallurgical coal NOx Smog Sulfur dioxide Toxic heavy metals
Coal mining	Blackdamp Black lung disease Coal dust Coalfields Coal gas homogenization liquefaction mining disasters in the United States mining region refuse slurry town Environmental issues in Appalachia Environmental justice and coal mining in Appalachia Firedamp Health and environmental impact of the coal industry Health effects of coal ash History of coal mining Hydrogen sulfide Mining regions Outbursts Peak coal Problems in coal mining Refined coal Whitedamp
Note: [1] Peat is considered a precursor to coal. Graphite is only technically considered a coal type.