Energy, Complexity and Wealth Maximization by Robert Ayres

Author:Robert Ayres
Language: eng
Format: epub, pdf
Publisher: Springer International Publishing, Cham

Electrochemistry —the application of electrolysis—also became industrially practical in the 1880s. The first, and most important, industrial electrolytic process was discovered in 1887 independently by Paul Heroult and France and Charles M. Hall in the U.S. It was a practical way of producing aluminum from aluminum oxide (alumina). To avoid the classic difficulty that defeated earlier efforts (that electrolysis of aluminum salts dissolved in water produced aluminum hydroxide, not aluminum metal), both inventors came up with the same solution. They dissolved aluminum oxide in molten cryolite a mineral (sodium-aluminum fluoride) found originally in Greenland and later made synthetically. This process was commercially exploited in both countries within 2 years. The price of metallic aluminum dropped rapidly, from $2/lb in the late 1880s, to $0.30/lb by 1897. Not surprisingly, many new applications of aluminum emerged, starting with pots and pans for the kitchen, which were previously made from cast iron and didn’t conduct heat very well.

Curiously, the availability of metallic aluminum had no real impact on the infant aircraft industry in its first three decades, during which air-frames were made from wood and wire and surfaces were often made of fabric. It was 1927 when the first all-metal plane (Ford Tri-motor) was built. Needless to say, the commercial airline industry, in its present form, could not exist without aluminum. The next generation Boeing 787 “Dreamliner” will be the first to utilize significant quantities of carbon-fiber composites materials in place of aluminum.

The second important electrolytic process (1888) was Castner’s system for manufacturing metallic sodium or sodium hydroxide (and chlorine) from fused sodium chloride, better known as common salt. At first, it was sodium hydroxide that was the important product. It was used in soap-making and for “whitening” illuminating oil for kerosene lamps, and later for converting bauxite to alumina. At first, chlorine was a cheap by-product, used initially—and still today—as a disinfectant for swimming pools and municipal water treatment. However, chlorine was soon in demand for a variety of chemical purposes, as well as for bleaching paper.

But the German discovery of a host of uses of chlorine in organic chemistry was the game-changer. Today, chlorine is one of the most important basic industrial materials, with a host of important uses from plastics (e.g. polyvinyl chloride) to insecticides (beginning with DDT). The cumulative economic impact of electro-metallurgy and electrochemistry has clearly been enormous, although most of it was not felt until many years after the key manufacturing innovations.

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