ALTERNATIVE POWER :
Propulsion After Petroleum
A little more than one hundred years ago, any conveyance not propelled by a horse or mule was considered an alternative power vehicle. The thought of being taken from place to place in any kind of mechanically powered contraption was considered ridiculous by most. By the turn of the twentieth century, however, vehicles powered by steam, electricity, and petroleum had captured the imagination of the buying public and were being sold in ever-increasing numbers. As oil became more available, gasoline-fueled vehicles came to dominate the market and all but a tiny number of their steam- and electric-powered counterparts were consigned to history, and the definition of an automobile propulsion system became extremely narrow. By 1910, the typical vehicle was any car, truck, or motorcycle powered by a gasoline-powered, piston-driven, internal combustion engine. As the piston engine gained a reputation for power and reliability, more and more capital resources were channeled toward perfecting it and a complicated fuel refining and distributing infrastructure was developed to support it.
The reasons that gasoline-powered vehicles became so popular are easy to appreciate. Gasoline is energy dense, can be transferred quickly for refueling, and was readily available in America thanks in part to the discovery of oil at Spindletop near Beaumont, Texas in 1901. In the opinions of many, these qualities outweighed drawbacks such as the excessive noise generated by internal combustion engines and their difficult starting, unpleasant odors, and dirty operation. As a result, gasoline-powered vehicles flourished for almost a century. Yet a small, but persistent contingent of free thinking engineers and enthusiasts never stopped considering alternative means to power automobiles. Recent concerns about the environment, social responsibility, the uncertain availability of imported oil, and the recent spike in gasoline prices have brought about renewed interest in their visions of alternative forms of vehicle power.
The wide variety of alternative power systems can be classified into two groups: those that use fuels other than gasoline and those that use mechanical systems that do not involve reciprocating mechanical components (such as pistons) driven by internal combustion. Electric and steam-powered cars are obvious examples of alternative power, but it would be equally as appropriate to consider an internal combustion engine an alternative power unit if it uses natural gas. Similarly, it would also be appropriate to consider a gasoline-fueled engine an alternative power unit if it is configured as a turbine.
The oldest method of vehicle propulsion, and one of the first to be discarded by modern engineers, was steam power. Built by French Army engineer Nicolas Cugnot in 1769, the world’s first automobile was propelled by steam. Though impractically large and ponderous, it demonstrated that it was possible to convert reciprocating motion (such as that produced by a steam piston) into rotational motion (to turn the drive wheels). The Stanley brothers and numerous other manufacturers engineered practical and affordable light steam-powered vehicles prior to the turn of the twentieth century, but the fundamental problems with cold-starting, special maintenance requirements, and high fuel consumption could not be overcome. While the last production steam car made in America was the California-built 1931 Doble, steam power trucks were made in England into the early 1950s. Although a tiny number of engineers still tinker with steam power, it is not regarded as viable.
Electricity was first used to power an automobile in about 1832 by Robert Anderson of Scotland. Women of the late 1800s and early 1900s favored electric vehicles because they were quiet, clean running, and easy to operate. They did not require a complicated starting procedure that involved raising the hood to prime cylinders with gasoline, bending over to turn a hand crank, or soiling one’s gloves to make mechanical adjustments. Yet while their reasonably efficient motors delivered a constant supply of torque, battery technology was so limited that they could only travel about 40 or 50 miles on one charge, which often required that a vehicle be plugged-in for six to eight hours. These limitations could not be overcome and the last quantity-produced American electric car was the 1939 Detroit Electric. The severe lack of fuel available for civilian consumption in Europe during World War II fostered a brief revival of electric vehicles abroad, but these were rapidly phased out after the armistice.
Prior to the introduction of the General Motors EV1 in 1996, the makers of electric vehicles after World War II were small companies, usually run by enthusiastic optimists with little background in finance or manufacturing. But since battery technology was still not sufficiently advanced, these vehicles were no more practical than their pre-war counterparts. One solution to the short range of battery-only electrics is the application of solar cells, which convert sunlight into electrical energy for storage in batteries. Yet while solar enginery is considered one of the most promising sources of environmentally friendly power generation, the majority of solar cells are less than ten percent efficient and vehicles powered by sunlight must be super-light and ultra-streamlined, which makes them extremely impractical.
Another propulsion system that does not use reciprocating mechanical components driven by internal combustion is the gas turbine. Gas turbines are powered by exploding gasses passing over fan blades in a continuous combustion process. Turbines operate smoothly and have greater peak efficiency than piston engines, but are better suited for steady-state uses like those of power plants and other industrial applications. Built by the British firm Rover in 1950, the first automotive gas turbine drew a great deal of attention because of its exotic engineering, unconventional appearance, and strange sound. Anxious to explore the potential of turbine power, other major manufacturers such as Fiat in Italy, Socema Gregoire in France, and Ford in America built experimental turbines. The company most closely associated with this advanced technology was Chrysler, whose turbine program lasted from 1954 through 1979. Today, Chrysler is best remembered for the 50 (some sources say 55) turbine vehicles built in 1963, most of which were loaned free of charge to preferred customers for evaluation in everyday driving situations. High fuel consumption, high production costs, and difficulties experienced by drivers who were not used to the behavior of a turbine engine doomed the effort. With the exception of an estimated six that were donated to museums and two retained by Chrysler engineering, all were dismantled so Chrysler could avoid paying import duties on the Italian Ghia-built bodies.
Like the turbine, a Wankel (rotary) engine delivers power by spinning (rather than reciprocating) motion, although not by continuous combustion. Instead of pistons that travel up and down in a cylinder, a triangular rotor revolves in an oval housing. For every rotation of the rotor, the engine produces three power strokes, providing far more power than a piston engine of equivalent displacement. (A quasi-turbine operates under the same principle, but produces four power strokes per revolution with far less vibration because of its four-sided rotor.) In production from 1964 through 1967, the German NSU Wankel Spyder was the world’s first production car with a rotary engine. In 1967 Mazda of Japan became the first manufacturer to produce a two rotor Wankel engine, which it installed in the sporty Cosmo until 1972. Since that time, Mazda has continued to develop and refine the rotary engine and their current Wankel-powered vehicle is the unusually fast RX-8.
Among the least practical alternative power sources are jet, rocket, and nuclear power. Jet engines channel rapidly expanding, combustible gasses through a nozzle at the back, using thrust to force a vehicle forward. Because the nozzle can be designed to change its shape and size, jet engines can run at a fixed rate while producing variable power from the changing nozzle. Like jets, rocket engines produce thrust through chemical reactions, but are self-contained and do not require outside air to supply the oxygen needed to support combustion. Built in Germany, an experimental 1928 Opel was among the first rocket-powered automobiles and reached a modest 47 miles per hour during testing. Although another Opel (powered by 24 solid rockets) achieved an astounding 143 miles per hour, high cost and serious safety concerns ensured that, while rocket- and jet-powered vehicles would continue to be built, they would be used almost exclusively for highly specialized purposes under controlled conditions, such as for land speed record breaking. In a class by itself, nuclear power has yet to be adapted for automotive use. The great expense of developing a safe and compact nuclear engine, coupled with the dire consequences that would result from its catastrophic failure have prevented this form of power from reaching even the experimental stage.
Because of the familiar engineering of the piston engine, alternative fuel technology is one of the simplest to implement since power can be derived from many different fuels. Although benzene had fueled most pioneering internal combustion engines, it was soon discovered that gasoline gave even greater performance. While gasoline was more difficult to refine from petroleum, public demand made it worth the investment. Over time, it was discovered that a wide range of fuels other than gasoline could be used to power piston engines. And while at least one early vehicle, the 1904 Tuck, built in Brooklyn, New York, used kerosene, the most viable alternative proved to be diesel.
Developed by German engineer Rudolf Diesel, the diesel engine used fuel that required less refining than gasoline and was less expensive to buy. Diesel engines proved to be well suited for commercial uses because of their extremely high torque ratings. Recognizing diesel fuel’s potential for non-commercial applications, Mercedes-Benz became the world’s first manufacturer to offer a diesel engine in a production car: the 1936 260D. American manufacturers also experimented with diesel technology, and diesel-powered cars even raced at Indy prior to World War II. One of the first domestic production diesel vehicles was the 1968 Checker, built in Kalamazoo, Michigan. General Motors introduced a diesel V-8 in 1978, but it suffered from serious reliability problems. Only a tiny fraction of those built are still on the road. Modern diesel engines, many of which are turbocharged, are specially engineered from scratch to improve reliability, and have won back public confidence in their design.
A modern offshoot of diesel technology, biodiesel is a mixture of diesel fuel and biological products, such as cooking oil, which were once regarded as a waste product to be discarded. Cooking oil behaves as a natural solvent that removes impurities from fuel lines, improves fuel efficiency, and reduces friction. Because of these qualities, engines adapted for biodiesel fuel use require the application of special components that would not degrade over time. A number of facilities exist throughout the United States that can convert a diesel engine into a biodiesel unit. Biodiesel-powered vehicles are currently receiving a great deal of attention thanks to high-profile enthusiasts like country music star Willie Nelson.
The same circumstances that made electric cars viable in Europe during World War II, also made vehicles that burned coal gas practical. Also called “wood gas,” the fuel was created by partially burning wood or coal to produce a gaseous substance that could be used for combustible fuel. Although the fuel gave poor performance and the gasification process created excessive air pollution, it was deemed acceptable during wartime because it allowed a large number of vehicles to remain operational with the addition of a special gasification apparatus and a few straightforward engine modifications. Bulky and unattractive, virtually all gasification systems were removed from vehicles immediately after the war and cars so equipped are now extremely rare.
Other alternative fuels that can be adapted to modern internal combustion engines without significant re-engineering are compressed natural gas (CNG), propane/liquefied petroleum gas (LPG), and ethanol. Although their energy densities differ from gasoline, these fuels are becoming increasingly available, and a number of new automobiles carry a Flexible Fuel Vehicle (FFV) designation because of their adaptability.
Hybrid automobiles combine two forms of power, most commonly a gasoline engine and an electric motor. Gas-electric hybrids were developed to overcome the limited range and lengthy recharging time associated with battery-only electrics. Though gas-electric hybrids are receiving a great deal of manufacturer and press attention, the concept is not new. In 1902 Ferdinand Porsche constructed one of the earliest gas-electric hybrids, which employed hub motors built into the front wheels that even today are considered advanced. One of the most intriguing American gas-electric hybrids was the Woods Dual Power. Built in Chicago, Illinois in 1917 and 1918, the Woods drive system consisted of a four-cylinder engine and an electric motor, which could be operated separately or together. But instead of embodying all of the advantages of gasoline cars with those of electric cars, the Woods embodied all of their respective disadvantages. It was heavy, expensive to buy, complicated to operate, difficult to service, and had a top speed of just 35 miles per hour. Although modern computerized engine management systems have made gas-electric systems practical for real-world driving, hybrid vehicles are regarded as temporary stopgaps that many expect will be phased out when other power systems are perfected and the infrastructure to support them is in place.
Among the most eagerly awaited alternatives, and one that has existed for several decades, is hydrogen power. The most commonly occurring element in nature, hydrogen costs very little for the amount of power it produces. For use in an internal combustion engine, hydrogen is injected into the cylinders in much the same way as propane. To power electric motors, hydrogen creates electricity by splitting water molecules in fuel cells. The 1966 General Motors Electrovan was among the world’s first hydrogen fuel cell vehicles. In 2005, Honda became the first major manufacturer to deliver a production fuel cell passenger vehicle to a customer who, appropriately, resided in Southern California. Regardless of the application, hydrogen requires a great deal of energy to isolate as fuel, but produces no harmful emissions; only water vapor.
Although circumstances prevailing during the oil shocks of the 1970s generated a level of interest in alternative power similar to that of today, the technologies of the time were insufficiently developed to offer consumers a realistic choice. And while the firms that have made a significant investment in petroleum-powered vehicles are reluctant to change their product mix, many national, state, and local governments are encouraging—even mandating—the development of vehicles that use non-petroleum based fuels. This prompting has resulted in experimentation with a large number of both rediscovered and newly developed technologies, which today offer an interesting contrast to those that existed during the last century.