In 1872 the Mekarski air engine was used for street transit, consisting of a single-stage engine. It represented an extremely important advance in terms of pneumatic engines, due to its forward thinking use of thermodynamics, ensuring that the air was heated, by passing it through tanks of boiling water, also increasing its range between fill-ups. Numerous locomotives were manufactured and a number of regular lines were even opened up (the first in Nantes in 1879). In 1892, Robert Hardie introduced a new method of heating that at the same time served to increase the range of the engine.
However, the first urban transport locomotive was not introduced until 1898, by Hoadley and Knight, and was based on the principle that the longer the air is kept in the engine the more heat it absorbs and the greater its range. As a result they introduced a two stage engine.
Charles B. Hodges will always be remembered as the true father of the compressed air concept applied to cars, being the first person, not only to invent a car driven by a compressed air engine but also to have considerable commercial success with it. The H.K. Porter Company of Pittsburgh sold hundreds of these vehicles to the mining industry in the eastern United States, due to the safety that this method of propulsion represented for the mining sector. Later on, in 1912 the American’s method was improved by Europeans, adding a further expansion stage to the engine (3 stages).
In January 1932 what appears to be the first journalistic article ever written about a car driven by compressed air was published.
The first hybrid diesel and compressed air locomotive appeared in 1930, in Germany. The pressures brought to bear by the oil industry in the transport sector were ever greater and the truth of the matter is that they managed to block investigation in this field. After the Second World War the term “air engine” was never again used in textbooks referring to compressed air or pneumatic locomotives and, whenever they were mentioned the article would go on to state that these engines were of little use or efficiency.
In 1979, Terry Miller decided that compressed air was the perfect medium for storing energy. He developed Air Car One, which he built for $ 1,500. Terry’s engines showed that it was feasible to manufacture a car that could run on compressed air. He patented his method in 1983