Coal

Coal is that sooty black stuff one usually associates with the late 1800s and Santa Claus. But coal, a fossil fuel, is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide anthropogenic sources of global warming. Gross carbon dioxide emissions worldwide from coal usage are slightly more than those from petroleum and about double the amount from natural gas.[1] Burning coal to produce electricity also releases the most carbon dioxide per kWh generated.[2] Fun stuff. Exposure to coal in various forms is carcinogenic to humans.[3]

It's gettin' hot in here
Global warming
Feverish dreams
Hot-headed goons
v - t - e

Types of coal
  • Lignite – brown[note 1] and ugly, really smoky,[note 2] and isn't usually transported very far from where it is mined. It is usually mined open pit and thus creates huge disruptions of the natural environment for decades, even centuries.
  • Bituminous – this is what most people think of when they think of coal. Black, and still rather smoky and stinky. Most Appalachian coal is bituminous. Wyoming's Powder River Basin coal is "sub-bituminous," which is somewhere between bituminous and the lower-quality lignite, hence cheaper, but for some reason has a lower sulfur content so it also widely used.
  • Anthracite – the better stuff. Well, better than the other two varieties, at least. Cleaner burning but pricey and rarely used.

Clean coal?
See the main article on this topic: Clean coal

Clean coal is a buzzword oxymoron for coal power that is "clean" because they pump the emissions underground.

Coal mining

Coal mining is environmentally destructive and dangerous. Coal can cause "Black Lung," also known as coal worker' pneumoconiosis.[4] On multiple occasions, miners have been trapped in coal mines for extended periods of time. Coal mining is often associated with Kentucky, the Ruhr, Silesia and Wales.

Reducing the danger to the miners often means increasing the environmental damage; open-pit mining is not nearly as hazardous as the underground variety, and mountaintop removal also much safer, but it also means mucking up the local environment to a much greater degree.

Formation

Coal begins as layers of plant matter accumulate at the bottom of a body of water. For the process to continue, the plant matter must be protected from biodegradation and oxidization, usually by mud or acidic water; the wide shallow seas of the Carboniferous period provided such conditions. This trapped atmospheric carbon in the ground in immense peat bogs that were eventually covered over and deeply buried by sediments, under which they metamorphosed into coal. Over time, the chemical and physical properties of the plant remains (believed to mainly have been fern-like species antedating more modern plant and tree species) were changed by geological action to create a solid material.

In medicine

Coal oil was once used as a panacea,[5] but has fallen into disuse. Coal tar, on the other hand, is an approved FDA ingredient for over-the-counter topical medicines. There is no evidence that coal tar causes cancer from short-term, low concentration topical use,[6] even though coal tar is carcinogenic in humans from high-dose occupational exposure.[7]

gollark: It's been decades since tar and yet still nobody has come up with a widely used and actually good archive format.
gollark: it's actually an ar archive containing two xz-compressed tar archives.
gollark: Nope.
gollark: You heard me. Possibly.
gollark: I disagree with apt's packaging format slightly on ethical grounds.

See also
For those of you in the mood, RationalWiki has a fun article about coal.

Notes
  1. Actually in most cases a piece of lignite is black or blackish, but if you "draw" with it, the line is brown
  2. Lignite commonly has a rather high sulfur content making it "dirtier" still

References
  1. What are the sources of energy-related carbon dioxide emissions by type of fuel for the United States and the world?, Energy Information Administration
  2. How much carbon dioxide (CO2) is produced per kilowatt-hour when generating electricity with fossil fuels?, EIA
  3. IARC Monographs
  4. Coal Mining-Related Respiratory Diseases, CDC
  5. Coal-Oil as a Medicinal Agent by John Mulvany (1869) Br. Med. J. 1(430):280–281.
  6. No Increased Risk of Cancer after Coal Tar Treatment in Patients with Psoriasis or Eczema by Judith H.J. Roelofzen et al. (2010) Journal of Investigative Dermatology Volume 130, Issue 4, Pages 953–961.
  7. Supplement 7 (1987) pp. 175-176 International Ageency for Research on Cancer.
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