Hall–Héroult process
Electrochemicals are chemicals and metals produced by an electrolytic process. Important examples include aluminum made by the Hall–Héroult process and chlorine and caustic (sodium and potassium compounds). Chlorine and caustic had been produced by chemical processes but producing aluminum this way was prohibitively expensive. A large plant using the Hall–Héroult process was opened in Pittsburgh, USA in 1888 and others opened around the world. Falling electricity prices in the early 20th century greatly lowered the cost of making electrochemicals. There was high demand for aluminum for aircraft during World War I and afterward for commercial aviation.