Coal: chemical gold

Coal has been in the news lately, with a deadly explosion in a West Virginia coal mine and a near-disaster at another mine in China. Leaving aside the dangers, both human and environmental, what is coal used for?

Most people will be aware that about half the electricity in the U.S. is generated by burning coal (world-wide, the figure is about 40%). Burning coal has been used historically to create steam for locomotives, ships, and machinery, and as a direct fuel for heating homes and businesses. I’ll focus on more obscure, non-fuel uses.

One use that is not really obscure, but involves burning coal, is steel manufacture. Coke, coal that has been baked to drive off volatiles, is the main fuel for steel blast furnaces.

Diverse chemicals derive directly or indirectly from coal. Coal tars are residual by-products of coal gasification. Coal gas was used for city street lighting in the decades before electric lights became common. Coal tar chemicals led to the development of some insecticides, paint thinners, and moth balls, as well as mauve and other synthetic dyes (see Mauve: How One Man Invented a Color That Changed the World, by Simon Garfield, a good read) including the color in the 1882 stamp seen here.

Coal tar chemicals yield both aspirin and the plastic bottle containing the medication. Fertilizer, smelling salts, and baking powder have a chemical heritage in the ammonia derived from the coking process. Soap, nylon, and synthetic rubber in car tires have coal-derived components.

Activated charcoal filters, from air cleaners to kidney dialysis machines, are made from coal. TNT explosives and perfumes have coal in their pasts.

The United States owns the greatest coal reserves in the world, at 27% of the total (Russia is #2 at 17%), but China is the world production leader with almost 40% (U.S. is #2 at 17%).  China’s industrialization means it exports less and less coal, using most of it internally as the world’s largest coal consumer, with the consequence that Australia is the leading coal exporter, at about a third of the world total (and Indonesia is the #2 exporter, with 13%).