There is no question that pollution from automobiles is a major problem in industrialized countries and is increasing in developing nations. And the number of cars is increasingly rapidly: in the United States, the automobile population has increased 6X faster than the human population and 2X faster than the number of new drivers (Motavelli, 2000). At the same time, the average fuel economy of the 2001 fleet decreased to 20.4 miles per gallon, the same it was in 1980. This decrease is fueled by the growing trend in inefficient SUVs. As over 50% of the USA’s oil comes from overseas, the dangerous level of waste promoted by inefficient vehicles makes this more than simply an environmental issue.
What are some of the long-term renewable solutions to the political and environmental dangers that pollution and inefficiency pose?

Battery-powered vehicles. There are several electric car models on the market in the making. As of now, their economic viability is restrained by the relatively short distance that can be traveled between recharging and their lower-than-average maximum speeds. Considering the advantages that standard cars have over battery-powered cars, there is little economic incentive to buy battery-powered cars, but their environmental benefits are enormous. Although it requires factory pollution to create the electricity necessary to charge the vehicles, it would take 13 electrical cars to equal the emissions produced by one standard car (Motavelli, 2000). Research is continuing to make battery-powered cars, but there exist two other promising options.

Hydrogen Fuel-Cell Cars. A fuel cell produces electricity by introducing hydrogen to a cathode, which pulls the electron from the hydrogen molecule. The positively-charged hydrogen ion travels through an electrolyte solution to the anode, while the electron – which is incapable of traveling through the solution – travels along a wire to the anode. The movement of the electron along this wire produces the electricity. When the electron and hydrogen ion meet at the anode, they combine with oxygen to form water, the waste product of fuel cells.
Fuel-cells are extremely clean and efficient, and seem to be a promising energy source. However, as of now, the hydrogen that is used in fuel-cells must be obtained somewhere – most commonly, fossil fuels. There is hope for developing zero-emission hydrogen using solar energy to split water into oxygen and hydrogen.
Noting the possible economic benefits, and the willingness of consumers to buy clean cars at reasonable prices, automobile manufacturers have been seriously looking into hydrogen fuel-cell cars. For example, General Motors has been researching a 100% fuel-cell powered car that could change the basis of traditional car design by removing the drive-shaft used in internal combustion engines, which frees up the body of the car for substantial reorganization
(http://www.sciam.com/print_version.cfm?articleID=00034FE5-BA99-1D80-90FB809EC580000).

Hybrid cars. Hybrid cars are the most currently feasible reduced-emission vehicles and provide promise for a shift toward zero-emission vehicles. Hybrid cars work by combining an internal-combustion engine with an electric engine to maximize the efficiency of both. The current levels of horse-power offered by standard engines are only fully utilized during fast accelerations, and driving uphill. Therefore, hybrid cars use both of their engines only when truly necessary (http://www.auto.howstuffworks.com/hybrid_car.htm). As a result, hybrid cars have much higher fuel-efficiencies and do not require recharging as a completely electric car would.
Hybrid cars are now available of competitive prices and car companies have been making profits since 2001. As of now, there are three models on the market (Toyota Prius, Honda Insight and the Honda Civic Hybrid), with more expected to follow. The limited popularity of hybrid cars at the moment seems to be largely a result of low gas prices in the United States. As gas prices have risen recently, there has been an increasing demand for efficient cars.

Suggestions for further readings:

Borroni-Bird, Christopher E. Designing AUTOnomy. http://www.sciam.com/print_version.cfm?articleID=00034FE5-BA99-1D80-90FB809EC580000. 2002.

California Air Resources Board. Major Automotive Fuel Cell Programs http://www.arb.ca.gov/msprog/zevprog/fuelcell/kalhammer/techreport/sec3_3.pdf. 2002

Fantes, Francisco. Solar Hydrogen Energy: Mining the Oceans for the Holy Grail. Harvard Science Review, winter 2002.

Hubler, Shawn, Chalk One Up for Hybrids. Http://www.calendarlive.com/printedition/calendar/cl_et_hubler26mar26.story. 2002.

Motavelli, Jim. Forward Drive : The Race to Build “Clean” Cars for the Future.
San Francisco : Sierra Club Books, 2000

Nice, Karim. How Hybrid Cars Work. http://auto.howstuffworks.com/hybrid_car.htm 2002.

Sierra Club, Energy Fact Sheet. Http://www.sieraclub.org/energy/factsheet.asp 2001