Us Vehicle Petroleum

No change

No change

Year

▲ Four scenarios project petroleum use over the next quarter of a century. "No change" assumes that fuel consumption per vehicle remains steady at 2008 levels. "Baseline" adds evolutionary improvements in technology, whereas "baseline + hybrids + diesels" assumes the gradual addition of gasoline-electric hybrid and diesel vehicles into the fleet, and "composite" adds to the mix a slowing in the growth of vehicles sold and vehicle-kilometers traveled.

Year

▲ Four scenarios project petroleum use over the next quarter of a century. "No change" assumes that fuel consumption per vehicle remains steady at 2008 levels. "Baseline" adds evolutionary improvements in technology, whereas "baseline + hybrids + diesels" assumes the gradual addition of gasoline-electric hybrid and diesel vehicles into the fleet, and "composite" adds to the mix a slowing in the growth of vehicles sold and vehicle-kilometers traveled.

ample), more efficient transmissions, and low-emission diesels with catalysts and particulate traps in the exhaust, and perhaps new approaches to how the fuel is combusted might be included as well. Hybrids, which combine a small gasoline engine and a battery-powered electric motor, are already on the road, and production volumes are growing. These vehicles use significantly less gasoline in urban driving, have lower benefits at highway speeds and cost a few thousand dollars extra to buy.

Researchers are exploring more radical propulsion systems and fuels, especially those that have the potential for low life-cycle carbon dioxide emissions. Several organizations are developing hydrogen-powered fuel cell vehicles in hybrid form with a battery and an electric motor. Such systems could increase vehicle efficiency by a factor of two, but much of that benefit is offset by the energy consumed and the emissions produced in making and distributing hydrogen. If the hydrogen can be produced through low-carbon-emitting processes and if a practical distribution system could be set up, it has low-greenhouse-emissions potential. But it would take technological breakthroughs and many decades before hydrogen-based transportation could become a reality and have widespread impact.

Hydrogen is, of course, an energy carrier rather than an energy source. Electricity is an alternative energy carrier with promise of producing energy without releasing carbon dioxide, and various research teams are looking at its use in transportation. The major challenge is coming up with a battery that can store enough energy for a reasonable driving range, at an acceptable cost. One technical barrier is the long battery recharging time. Those of us used to filling a 20-gallon tank in four minutes might have to wait for several hours to charge a battery. One way around the range limitation of electric vehicles is the plug-in hybrid, which has a small engine on board to recharge the battery when needed. The energy used could thus be largely electricity and only part engine fuel. We do not yet know whether this plug-in hybrid technology will prove to be broadly attractive in the marketplace.

Beyond adopting improved propulsion systems, a switch to lighter-weight materials and different vehicle structures could reduce weight and improve fuel consumption without downsizing. Obviously, though, combining lighter materials and smaller vehicle size would produce an even greater effect. Maybe the way we use vehicles in the future will differ radically from our "general purpose vehicle" expectations of today. In the future, a car specifically designed for urban driving may make sense. Volkswagen, for example, has a small two-person concept car prototype that weighs 640 pounds (290 kilograms) and consumes one liter of gasoline per 100 kilometers (some 240 miles per gallon—existing average U.S. light-duty vehicles use 10 liters per 100 kilometers, or just under 25 miles per gallon). Some argue that downsizing reduces safety, but these issues can be minimized.

Promoting Change better technology will undoubtedly improve fuel efficiency. In the developed world, markets may even adopt enough of these improvements to offset the expected increases in the number of vehicles. And gasoline prices will almost certainly rise over the next decade and beyond, prompting changes in the way consumers purchase and use their vehicles. But market forces alone are unlikely to curb our ever growing appetite for petroleum.

A coordinated package of fiscal and regulatory policies will need to come into play for fuel-reduction benefits to be realized from these future improvements. Effective policies would include a "feebate" scheme, in which customers pay an extra fee to buy big fuel-consumers but get a rebate if they buy small, fuel-efficient models. The feebate combines well with stricter Corporate Average Fuel Economy (CAFE) standards—in other words, with regulations that require automobile makers to produce products that consume less fuel. Adding higher fuel taxes to the package would further induce people to buy fuel-efficient models. And tax incentives could spur more rapid changes in the production facilities for new technologies. All these measures may be needed to keep us moving forward. ®

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