Hybrid Vehicle Technologies

Summary

Hybrid vehicle technologies use shared systems of electrical and gas power to create ecologically sustainable industrial and passenger vehicles. With both types of vehicles, the main goals are to reduce hazardous emissions and conserve fuel consumption.

Definition and Basic Principles

As the word “hybrid” suggests, hybrid vehicle technology seeks to develop an automobile (or, more broadly defined, any power-driven mechanical system) using power from at least two different sources. Before and during the first decade of the twenty-first century, hybrid technology emphasized the combination of an internal combustion engine working with an electric motor component.

Background and History

Before technological development of what is now called a hybrid vehicle, the automobile industry, by necessity, had to have two existing forms of motor energy to hybridize—namely internal combustion in combination with some form of electric power. Early versions of cars driven with electric motors emerged in the 1890s and seemed destined to compete very seriously with both gasoline (internal combustion engines) and steam engines at the turn of the twentieth century.

Although development of commercially attractive hybrid vehicles would not occur until the middle of the twentieth century, the Austrian engineer Ferdinand Porsche made a first-series hybrid automobile in 1900. Within a short time, however, the commercial attractiveness of mass-produced internal combustion engines became the force that dominated the automobile industry for more than a half century. Experimentation with hybrid technology as it could be applied to other forms of transport, especially motorcycles, however, continued throughout this early period.

By the 1970s the main emerging goal of hybrid car engineering was to reduce exhaust emissions; conservation of fuel was a secondary consideration. This situation changed when, in the wake of the 1973 Arab-Israeli War, many petroleum-producing countries supporting the Arab cause cut exports drastically, causing a nationwide gas shortage and worldwide fears that oil would be used as a political weapon.

Until 1975 government support for research and development of hybrid cars was tied to the Environmental Protection Agency (EPA). In that year (and after at least two unsatisfactory results of EPA-supported hybrid car projects), this role was shifted to the Energy Research and Development Administration, which later became the US Department of Energy (DOE).

During the decade that followed the introduction of Honda's Insight hybrid car in 1999, the most widely recognized commercially marketed hybrid automobile was Toyota's Prius. Despite some setbacks in sales in 2010 following major recalls connected with (among other less dangerous problems) the malfunctioning anti-lock braking system and accelerator devices, the Prius models IV, V, and C still held the strongest positions in total hybrid car sales in the United States in 2015. Subsequent Toyota hybrid models, including the RAV4 Hybrid and the Highlander Hybrid, joined the Prius at the top of the heap in hybrid sales.

How It Works

“Integrated motor assist,” a common layperson's engineering phrase borrowed from Honda's late-1990's technology, suggests a simple explanation of how a hybrid vehicle works. The well-known relationship between the electrical starter motor and the gas-driven engine in an internal combustion engine (ICE) car provides a (technically incomplete) analogy: The electric starter motor takes the load needed to turn the crankcase (and the wheels if gears are engaged) until the ICE itself kicks in. This overly general analogy could be carried further by including the alternator in the system, since it relieves the battery of the job of supplying constant electricity to the running engine (recharging the battery at the same time).

In a hybrid system, however, power from the electric motor (or the gas engine) enters and leaves the drivetrain as the demand for power to move the vehicle increases or decreases. To obtain optimum results in terms of carbon dioxide emissions and overall fuel efficiency, the power train of most hybrid vehicles is designed to depend on a relatively small internal combustion engine with various forms of rechargeable electrical energy. Although petroleum-driven ICE's are commonly used, hybrid car engineering is not limited to petroleum. Ethanol, biodiesel, and natural gas have also been used.

In a parallel hybrid, the electric motor and ICE are installed so that they can power the vehicle either individually or together. These power sources are integrated by automatically controlled clutches. For electric driving, the clutch between the ICE and the gearbox is disengaged, while the clutch connecting the electric motor to the gearbox is engaged. A typical situation requiring simultaneous operation of the ICE and the electric motor would be for rapid acceleration (as in passing) or in climbing hills. Reliance on the electric motor would happen only when the car is braking, coasting, or advancing on level surfaces.

It is extremely important to note that one of the most vital challenges for researchers involved in hybrid-vehicle technology has to do with variable options for supplying electricity to the system. It is far too simple to say that the electrical motor is run by a rechargeable battery, since a wide range of batteries (and alternatives to batteries) exists. A primary and obvious concern, of course, will always be reducing battery weight. To this aim, several carmakers, including Ford, have developed highly effective first-, second-, and even third-generation lithium-ion batteries. Many engineers predict that, in the future, hydrogen-driven fuel cells will play a bigger role in the electrical components of hybrids.

Selection of the basic source of electrical power ties in with corollary issues such as calculation of the driving range (time elapsed and distances covered before the electrical system must be recharged) and optimal technologies for recharging. The simplest scenario for recharging, which is an early direct borrowing from pure-electric car technology, involves plugging into a household outlet (either 110 volt or 220 volt) overnight. But, hybrid-car engineers have developed several more sophisticated methods. One is a “sub-hybrid” procedure, which uses very lightweight fuel cells, mentioned above, in combination with conventional batteries (the latter being recharged by the fuel cells while the vehicle is underway). Research engineers continue to look at any number of ways to tweak energy and power sources from different phases of hybrid vehicle operation. One example, which has been used in Honda's Insight, is a process that temporarily converts the motor into a generator when the car does not require application of the accelerator. Other channels are being investigated for tapping kinetic-energy recovery during different phases of simple mechanical operation of hybrid vehicles.

Applications and Products

Some countries, especially Japan, have begun to use the principle of the hybrid engine for heavy-duty transport or construction-equipment needs, as well as hybrid systems for diesel road graders and new forms of diesel-powered industrial cranes. Hybrid medium-power commercial vehicles, especially urban trolleys and buses, have been manufactured, mainly in Europe and Japan. Important for broad ecological planning, several countries, including China and Japan, have incorporated hybrid (diesel combined with electric) technology into their programs for rail transport. The biggest potential consumer market for hybrid technology, however, is probably in the private automobile sector.

By the second decade of the twenty-first century, a wide variety of commercially produced hybrid automobiles were on European, Asian, and American markets. Among U.S. manufacturers, Ford developed the popular Escape and Mustang, and General Motors produces models ranging from Chevrolet's economical Volt to Cadillac's more expensive Escalade. Japanese manufacturers Nissan, Honda, and Toyota have introduced several standard hybrid models, to which one should add Lexus's RX semi-luxury and technologically more advanced series of cars. Korea's Hyundai Elantra and Germany's Volkswagen Golf also competed for some share of the market.

At the outset of 2011, Lexus launched an ambitious campaign to attract attention to what it called its full hybrid technology (as compared with mild hybrid) in its high-end RX models. A main feature of the full hybrid system, according to Lexus, is a combination of both series and parallel hybrid power in one vehicle. Such a combination aims at transferring a variable but continuously optimum ratio of gas-engine and electric-motor power to the car. Another advance claimed by Lexus's full hybrid over parallel hybrids is its reliance on the electric motor only at lower speeds.

Early in 2011, Mercedes-Benz also announced its intention to capture more sales of high-end hybrids by dedicating, over a three-year period, more research to improve the technology used in its S400 model. Audi, a somewhat latecomer, unveiled plans for its first hybrid, the Q5, in 2011. It followed this with the release of its Audi e-tron and e-tron Sportsback, a plug-in hybrid version.

As fuel alternatives continue to be added to the ICE components of HEVs, advanced fuel-cell technology could transform the technological field that supplies electrical energy to the combined system.

Careers and Course Work

Academic preparation for careers tied to HEV technology is, of course, closely tied to the fields of electrical and mechanical engineering and, perhaps to a lesser degree, chemistry. All of these fields demand course work at the undergraduate level to develop familiarity not only with engineering principles but with basic sciences and mathematics used, especially those used by physicists. Beyond a bachelor's degree, graduate-level preparation would include continuation of all of the above subjects at more advanced levels, plus an eventual choice for specialization, based on the assumption that some subfields of engineering are more relevant to HEV technology than others.

The most obvious employment possibilities for engineers interested in HEV technology is with actual manufacturers of automobiles or heavy equipment. Depending on the applicant's academic background, employment with manufacturing firms can range from hands-on engineering applications to more conceptually based research and design functions.

Employment openings in research may be found with a wide variety of private-sector firms, some involving studies of environmental impact, others embedded in actual hybrid-engineering technology. These are too numerous to list here, but one outstanding example of a major private firm that is engaged on an international level in environmentally sustainable technology linked to hybrid vehicle research is ABB. ABB grew from late-nineteenth-century origins in electrical lighting and generator manufacturing in Sweden (ASEA), merging in 1987 with the Swiss firm Brown Boveri. ABB carries on operations in many locations throughout the world.

Internationally known U.S. firm Argonne National Laboratory not only produces research data but also serves as a training ground for engineers who either move on to work with smaller ecology-sensitive engineering enterprises or enter government agencies and university research programs.

Finally, employment with government agencies, especially the EPA, the DOE, and Department of Transportation, represents a viable alternative for applicants with requisite advanced engineering and managerial training.

Social Context and Future Prospects

Although obvious ecological advantages can result as more and more buyers of new vehicles opt for hybrid cars, a variety of potentially negative socioeconomic factors could come into play, certainly over the short to medium term. The higher sales price of hybrids that were available toward the end of 2010 already raised the question of consumer ability (or willingness) to pay more at the outset for fuel-economy savings that would have to be spread out over a fairly long time frame—possibly even longer than the owner kept the vehicle. It is nearly impossible to predict the number of potential buyers whose statistically lower purchasing ability prevents them from paying higher prices for hybrids. In the 2020s, consumers who purchased hybrid cars paid about 20 percent more than the cost of gas-fueled automobiles. Continued unwillingness or inability to purchase hybrids would mean that a proportionally large number of used older-model ICE's (or brand-new models of older-technology vehicles) would remain on the roads. This socioeconomic potentiality remains linked, of course, to any investment strategies under consideration by industrial producers of cars.

In the United States, the Society of Automotive Engineers (SAE) is an important source of up-to-date information for ongoing hybrid vehicle research for both engineering specialists and well-informed general readers.

Bibliography

Bethscheider-Kieser, Ulrich. Green Designed: Future Cars. Ludwigsburg, Germany: Avedition, 2008.

Clemens, Kevin. The Crooked Mile: Through Peak Oil, Hybrid Cars and Global Climate Change to Reach a Brighter Future. Lake Elmo, Minn.: Demontreville Press, 2009.

Fish, Tom. "The 10 Most Popular Hybrid Car Models in America." Newsweek, 14 May 2021, www.newsweek.com/most-popular-hybrid-car-models-america-1590402. Accessed 10 June 2022.

Lim, Kieran. Hybrid Cars, Fuel-Cell Buses and Sustainable Energy Use. North Melbourne, Australia: Royal Australian Chemical Institute, 2004.

Society of Automotive Engineers. 1994 Hybrid Electric Vehicle Challenge. Warrendale, Penn.: Society of Automotive Engineers, 1995.

United States. Department of Energy. "Alternative Fuels Data Center: Hybrid Electric Vehicles." Energy Efficiency & Renewable Energy, US Dept. of Energy, www.afdc.energy.gov/vehicles/electric‗basics‗hev.html. Accessed 10 June 2022.

Wendler, Andrew. "Best Hybrid Cars in 2022." Forbes, 27 May 2022, www.forbes.com/wheels/best/hybrid-cars/. Accessed 10 June 2022.