Over the first 127 years of the automobile, liquid hydrocarbons largely won the battle to serve as transportation fuels because they were best suited to the task. Evolution is all about the ability to adapt to surroundings. Organisms with traits suited to where they exist will thrive, everything else faces extinction or assimilation. What goes in the natural world is often equally true in the realm of the automobile.
It's been more than three centuries since Sir Isaac Newton penned his laws of motion. We'll skip the calculus of how force equals the rate of change of momentum and just cut to the chase. Making a vehicle move requires energy; fuels carry that energy.
To be practical for transportation, we need carriers that are energy-dense, inexpensive and easy to handle. Engineers, inventors and other hopefuls have long experimented with a wide assortment of fuels, the vast majority of which fell by the wayside as gasoline and diesel oil rose to dominance in the twentieth century.
As early as 1806, Nicéphore Niépce ran a single-cylinder riverboat engine using a mixture of coal dust and moss spores. Coal dust made a return appearance in an early series experimental engine tests by Rudolf Diesel in 1892 before he settled on his eponymous compression ignition design. It popped up again in the 1970s when General Motors researchers were looking for alternatives to Middle East oil.
While coal dust is energy dense, plentiful and cheap, it's messy to handle and has some explosive tendencies, as miners can readily attest. This particular evolutionary line has largely died out, but not before sharing some of its DNA with other parts of the fuel family tree through coal-to-liquid processes for producing synthetic gasoline.
By the time Karl Benz rolled out his Motorwagen in 1886, gasoline was the preferred energy source, though there were those that preferred batteries. Unfortunately, the batteries of the late 19th and early 20th centuries were sorely lacking in both energy density and durability. The limited range and high cost of early electric vehicles such as the Lohner-Porsche and Detroit Electric prevented them from gaining mainstream acceptance. Despite advances in battery chemistry, that problem persists today.
Discoveries of easily accessible crude petroleum in the late 1800s largely doomed batteries as an automotive fuel source for the next 100 years. Liquid hydrocarbons had all the desired traits with the main downsides being emissions, including carbon dioxide, and supplies that became increasingly concentrated in unstable parts of the world. While gasoline has been the dominant transport fuel, even it has evolved. In fact, there's no such thing as pure gasoline. What we know as gasoline is actually a blend of organic compounds including heptane and octane, additives to provide desirable traits like improved cold-start capability and knock resistance. For more than 50 years, tetraethyl lead was added to give gasoline more resistance to self-ignition. Octane inherently has this characteristic but because it comes out later in the crude oil distillation process, it's more expensive. Adding lead to the blend allowed the use of more heptane while staying knock free.
Of course, lead has its own problems, including potential brain damage when ingested. The catalytic converter ultimately killed lead in gasoline. The remarkable devices that did so much to clean up automotive emissions were fatally damaged by lead deposits on the catalyst. Since the mid-1970s, lead has been supplanted by a variety of othe knock inhibitors, but most pump gasoline today is blended with up to 10 percent ethanol as an alternative.
While various refined petroleum products remain the dominant species today, what the future holds is anyone's guess. Batteries continue to evolve, hydrocarbons derived from non-fossilized biomass, and even hydrogen all show tremendous potential for the future.