Hybrid Vehicles
The roughly 200 million automobiles and light trucks currently in use in the United States travel approximately 2.4 trillion miles every year, and consume almost two-thirds of the U.S. oil supply. They also produce about two-thirds of the carbon monoxide, one-third of the lead and nitrogen oxides, and a quarter of all volatile organic compounds (VOCs). More efficient transportation energy use could have dramatic effects on environmental quality as well as saving billions of dollars every year in our payments to foreign governments. In response to high gasoline prices in the 1970s and early 1980s, automobile gas-mileage averages in the United States more than doubled from 13 mpg in 1975 to 28.8 mpg in 1988.
Unfortunately, cheap fuel prices and the popularity of sport utility vehicles (SUVs) and light trucks in the 1990s caused fuel efficiency to slide back below where it was 25 years earlier. By 2002, the average mileage for U.S. cars and trucks was only 27.6 mpg. Amory B. Lovins of the Rocky Mountain Institute in Colorado estimated that raising the average fuel efficiency of the United States car and light truck fleet by one mile per gallon would cut oil consumption about 295,000 barrels per day. In one year, this would equal the total amount the Interior Department hopes to extract from the Arctic National Wildlife Refuge (ANWR) in Alaska.
It isn't inevitable that we consume and pollute so much. A number of alternative transportation options already are available. Of course the lowest possible fossil fuel consumption option is to walk, skate, ride a bicycle, or other forms of human-powered movement. Many people, however, want or need the comfort and speed of a motor vehicle. Several models of battery-powered electric automobiles have been built, but the batteries are heavy, expensive, and require more frequent recharging than most customers will accept. Even though 90% of all daily commutes are less than 50 mi (80 km), most people want the capability to take a long road trip of several hundred miles without needing to stop for fuel or recharging.
An alternative that appears to have much more customer appeal is the hybrid gas-electric vehicle. The first hybrid to be marketed in the United States was the two-seat Honda Insight. A 3-cylinder, 1.0 liter gas engine is the main power source for this sleek, lightweight vehicle. A 7-hp (horsepower) electric motor helps during acceleration and hill climbing. When the small battery pack begins to run down, it is recharged by the gas engine, so that the vehicle never needs to be plugged in. More electricity is captured during "regenerative" braking further increasing efficiency. With a streamlined lightweight plastic and aluminum body, the Insight gets about 75 mpg (33.7 km/l) in highway driving and has low-enough emissions to qualify as a "super low emission vehicle." It meets the most strict air quality standards anywhere in the United States. Quick acceleration and nimble handling make the Insight fun to drive. Current cost is about $20,000.
Perhaps the biggest drawback to the Insight is its limited passenger and cargo capacity. Although the vast majority of all motor vehicle trips made in the United States involve only a single driver, most people want the ability to have more than one passenger or several suitcases at least occasionally. To meet this need, Honda introduced a hybrid-engine version of its popular Civic line in 2002. With four doors and ample space for four adults plus a reasonable amount of luggage. The 5-speed manual version of the Civic hybrid gets 48 mpg in both city and highway driving. With a history of durability and consumer satisfaction in other Honda models, and a 10-year warranty on its battery and drive train, the hybrid Civic appears to offer the security that consumers will want in adopting this new technology.
Toyota also has introduced a hybrid vehicle called the Prius. Similar in size to the Honda Civic, the Prius comes in a four-door model with enough room for the average American family. During most city driving, it depends only on its quiet, emission-free, electric motor. The batteries needed to drive the 40-hp are stacked up behind the back seat providing a surprisingly large trunk for luggage. The 70-hp, 1.5 liter gas engine kicks in to help accelerate or when the batteries need recharging. Getting about 52 mpg (22 km/l) in city driving, the Prius is one of the most efficient cars on the road and can travel more than 625 mi (1,000 km) without refueling. Some drivers are unnerved by the noiseless electric motor. Sitting at a stoplight, it makes no sound at all. You might think it was dead, but when the light changes, you glide off silently and smoothly.
Introduced in Japan in 1997, the Prius sells in the United States for about the same price as the Honda hybrids. The Sierra Club estimates that in 100,000 mi (160,000 km), a Prius will generate 27 tons of CO2, a Ford Taurus will generate 64 tons, while the Ford Excursion SUV will produce 134 tons. In 1999, the Sierra Club awarded both the Insight and the Prius an "excellence in engineering" award, the first time this organization has ever endorsed commercial products.
Both Ford and General Motors (GM) have announced intentions to build hybrid engines for their popular sport utility vehicles and light trucks. This program may be more for public relations, however, than to save fuel or reduce pollution. The electrical generators coupled to engines of these vehicles will produce only 12 volts of power. This is far less than the 42 volts needed to provide drive the wheels. Instead, the electricity generated by the gasoline-burning engine will only be used to power accessories such as video recorders, computers, on-board refrigerators, and the like. Having this electrical power available will probably actually increase fuel consumption rather than reduce it. For uncritical consumers, however, it provides a justification for continuing to drive huge, inefficient vehicles.
In 2002, President G. W. Bush announced he was abandoning the $1.5 billion government-subsidized project to develop high-mileage gasoline-fueled vehicles started with great fanfare eight years earlier by the Clinton/Gore administration. Instead, Bush was throwing his support behind a plan to develop hydrogen-based fuel cells to power the automobiles of the future. Fuel cells use a semi-permeable film or electrolyte that allows the passage of charged atoms, called ions, but is impermeable to electrons to generate an electrical current between an anode and cathode.
A fuel cell run on pure oxygen and hydrogen produces no waste products except drinkable water and radiant heat. Fossil fuels can be used as the source for the hydrogen, but some pollutants are released (most commonly carbon dioxide) in the process of hydrogen generation. Currently, the fuel cells available need to be quite large to provide enough energy for a vehicle. Fuel cell-powered buses and vans that have space for a large power system are currently being tested, but a practical, family vehicle appears to be years away.
While they agree that fuel cells offer a wonderful option for cars of the future, many environmentalists regard putting all our efforts into this one project to be misguided at best. It probably will be at least a decade before a fuel-cell vehicle is commercially available.
Resources
Books
Hodkinson, Ron, and John Fenton. Lightweight Electric/Hybrid Vehicle Design. Warrendale, PA: Society of Automotive Engineers, 2001.
Jurgen., Ronald K., ed. Electric and Hybrid-electric Vehicles. Warrendale, PA: Society of Automotive Engineers, 2002.
Koppel, Tom. Powering the Future: The Ballard Fuel Cell and the Race to Change the World. New York: John Wiley & Sons, 1999.
Periodicals
"Dark Days For Detroit—The Big Three's Gravy Train in Recent Years—Fat Profits from Trucks—is Being Derailed by a New Breed of Hybrid Vehicles from Europe and Japan." Business Week, January 28, 2002, 61.
Ehsani, M., K. M. Rahman, and H. A. Toliyat. "Propulsion System Design of Electric and Hybrid Vehicles." IEEE Transactions on Industrial Electronics 44 (1997): 19.
Hermance, David, and Shoichi Sasaki. "Special Report on Electric Vehi cles—Hybrid Electric Vehicles take to the Streets." IEEE Spectrum 35 (1998): 48.
Jones, M. "Hybrid Vehicles—The Best of Both Worlds?" Chemistry and Industry 15 (1995): 589.
Maggetto, G. and J. Van Mierlo. "Fuel cells: Systems and applications—Electric vehicles, hybrid vehicles and fuel cell electric vehicles: State of the art and perspectives." Annales de chimie—science des matériaux. 26 (2001): 9.
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