Volatile gasoline prices that have spiked over $4 a gallon have sparked a lot of consumer interest in vehicles designed to cut gas usage. Concern about air pollution, carbon-dioxide emissions, and U.S. dependence on imported oil is also driving research into non-petroleum based fuels and technology.

	CR Quick Take
		A number of promising alternatives to the conventional, gasoline-powered car are being developed. • Hybrid vehicles are likely to continue generating consumer interest if gasoline prices remain high. • Plug-in hybrids represent the next phase of hybrid-vehicle development, allowing cars to run on cheaper, cleaner electricity for most trips, while using the a gas engine to give plug-ins the long-distance capability of conventional cars. • Renewable fuels made from farm crops will help, but they cannot yet replace more than a small percentage of U.S. petroleum needs. • Hydrogen fuel-cell cars, which are ultraclean and use no petroleum, are still at least a decade away from being practical alternatives. • Over the next 10 to 20 years, we are likely to see incremental improvements in a number of areas, which will help improve fuel economy, stretch petroleum supplies, and reduce pollution.

The good news is that automakers and other researchers have been working on a variety of alternatives to conventional gasoline-fueled, internal-combustion engines. But the reality is that only hybrids and "clean diesels" promise to be practical alternatives in the near future.


The petroleum problem

Some analysts see the spike in gasoline prices in the summer of 2008 as a sign of things to come. Experts argue that it's only a matter of time before increasing worldwide demand and tightening supplies of this declining resource drive pump prices still higher, especially because the U.S. is increasingly dependent on oil imports from politically unstable parts of the world.

Predictions about when this will happen range from a less than a decade to more than a century. For example, Colin Campbell, a petroleum geologist and former consultant to oil companies, has stated that petroleum will run short worldwide in about 20 years, by which time the U.S. will be importing 90 percent of its oil. In contrast, Michael C. Lynch, president of the consultant group Strategic Energy and Economic Research, says, "The pessimists underestimate how much oil will come on-line in the next few years. We'll still be using oil a hundred years from now, but a lot less of it. We'll see a gradual shift away from oil as nonemitting alternatives become more feasible."

Aside from pricing and supply issues, burning fossil fuels creates pollution-related health hazards and acid rain, and adds billions of tons of carbon dioxide (CO₂) to the atmosphere annually. CO₂ is considered a major contributor to global warming.


Searching for solutions

Technology can help, but as John Steele Gordon, a finance historian, has argued, a new technology replaces an older one only when it's cheaper, better, or both. So far, that's proved a stumbling block to many "green" vehicles that haven't been able to match the balance of price, convenience, performance, and driving range that conventional gasoline vehicles provide.

All-electric cars have failed to become commercially viable because of limited range and long recharge times. Alternative fuels have generated only niche markets. Clean-running hydrogen-powered cars are still in their infancy. And while diesels show promise, high fuel prices and the need for expensive emissions control systems have hindered their adoption.

The alternative that has gained the most acceptance so far is the gas-electric hybrid, an innovative technology that meets conventional cars halfway.