German engineer Rudolph Diesel patented the diesel engine in 1892. He first considered powdered coal as a possible fuel, but it proved difficult to inject into the cylinder and caused an explosion that destroyed the prototype engine. He later experimented with vegetable oils and successfully used peanut oil. Ultimately, Diesel settled on a stable byproduct of the petroleum refinement process that would come to be known as "diesel fuel."
St. Louis, Missouri, brewer Adolphus Busch became the first commercial builder of diesel engines in the United States after seeing one demonstrated at an exposition in Germany and purchasing a license from Diesel to manufacture and sell them in North America.
After World War I, sailors who had operated diesel-powered submarines began to adapt diesel engines for the peacetime economy. One modification was the development of the "semi-diesel" truck engine in the 1930s. Trucks equipped with this engine came to be nicknamed "smokers" because of their dark, sooty emissions.
Particularly since government began regulating diesel emissions in the late 1960s, engine manufacturers have substantially redesigned their products to run cleaner. Innovations such as cooled exhaust gas re-circulation, injection-timing delay and higher injection pressures - along with the development of progressively cleaner fuels - have reduced emissions from diesel engines by between 80 and 90 percent since the late 1980s. On average, today's diesel trucks emit nearly 70 percent less nitrogen oxide and 90 percent less particulate matter than in 1987.