Thomas Midgley Jr.

Thomas Midgley Jr. was an American mechanical and chemical engineer whose work reshaped two major branches of twentieth century energy technology, for better and for worse. Working for General Motors research laboratories, he developed tetraethyl lead as a gasoline additive in the early 1920s, a compound that eliminated engine knock and let automakers build higher compression, more fuel-efficient internal combustion engines; leaded gasoline became the standard motor fuel for decades before its severe public health and environmental costs led to its eventual phase-out. Later in the 1920s Midgley turned to refrigeration and developed the first chlorofluorocarbon refrigerants, marketed under the brand name Freon, which replaced the toxic and flammable refrigerants then in use and made household and commercial refrigeration and air conditioning dramatically safer and more widespread. Decades later, CFCs were found to deplete the stratospheric ozone layer and were phased out under international agreement. Midgley held more than a hundred patents over his career and is frequently cited in the history of technology as an example of how a single inventor's genuinely useful innovations can carry consequences that take decades to become apparent.