High oil prices and concerns about the long-term availability of oil have U.S. government officials singing the praises of hydrogen fuel cells as a solution to our nation’s transportation energy problem. But fuel cells, while a promising technology, could take more than 50 years to have a significant impact on gasoline consumption, according to estimates by MIT researchers. On the other hand, improved internal combustion engines and lighter vehicles could offset energy consumption much sooner, especially if consumers have incentives to buy them and manufacturers to make them.
“The potential for hydrogen fuel cells having an impact that you’d notice is a long way away,” says John Heywood, professor of mechanical engineering at MIT. The estimates assume that competitive fuel cell vehicles will be available within 15 years, an achievement that will require improvements, for example, in hydrogen storage and production and fuel-cell costs. But even if and when fuel-cell vehicles come with the price and performance that consumers want, it will still take decades more before such new vehicles work their way into widespread use.
One factor slowing the impact of any new vehicle technology – whether advanced internal combustion engine, hybrid, or fuel cell – is the average lifespan of a car, which is about 15 years, according to Heywood. Even as people buy cars with new technologies, old ones stay on the roads, continuing to burn fuel and emit carbon dioxide.
Also, as the example of hybrids shows, the market share of vehicles with radical new technologies increases only slowly, and it can take years before the new technology starts to appear in more than one vehicle in a manufacturer’s fleet. Hybrids were first introduced, in the United States, in 1999, and still only account for about one percent of vehicle sales. The MIT researchers estimate that, even after a competitive hydrogen fuel-cell vehicle is available, it will take roughly 25 years for these vehicles to make up 35 percent of new car and light-truck sales. And it will be an additional 20 years or so before these cars replace 35 percent of traditional vehicles on the road.
On the other hand, advanced internal combustion engines, which will likely be ready for the marketplace much sooner, and will require less retooling and so can spread through the fleet faster, could have a significant impact in about 20 years. Meanwhile, advanced, clean diesel engines and hybrids could both reach significant levels in about 30 years. In spite of the greater near-term promise of these technologies, however, there is no effort to develop them that’s as far along as the federal hydrogen research programs. “We’re not investing enough in developing a broad technology base we can draw on to deal with these problems,” Heywood says.
These rate of adoption numbers, which Heywood says are borne out by the rate with which efficient diesel engines have spread over the last 25 years in Europe, suggest that short-term changes in fuel consumption must come not from the development of new technologies, but from the wiser use of existing ones. “We don’t have any options other than to reduce the energy requirement in a major way,” he says. Consumers should buy smaller vehicles that use less gas, drive slower and for shorter distances, and optimize fuel economy by staying on top of routine maintenance, such as keeping their tires inflated properly.
Heywood admits these ideas might not be rapidly adopted: “It’s not American to conserve. We seem to have drifted into that attitude. Our culture doesn’t bring us up to think about conserving. It brings us up to think about consuming.”
Heywood says changes in behavior, however, could be encouraged in several ways. Crackdowns on speeding would save gas. High prices at the pump help some, but prices at the time of vehicle purchases are also important. Heywood suggests that, in addition to toughening government fuel economy standards, which would give manufacturers more incentive to make vehicles that use less gas, consumers should be awarded rebates when buying smaller, more economical cars, as well as be assessed extra fees when buying gas-guzzlers.
He also thinks a higher gas tax could be palatable, if presented correctly. The money could go into the highway trust fund, which he says is now suffering, providing a justification for the tax beyond just penalizing drivers. Since such a tax would be highly regressive, disproportionately affecting the poor, who might get stuck driving used SUVs, for example, Heywood also proposes a selective reduction in their income taxes to compensate.
Meanwhile, petroleum-based fuel consumption continues to increase, in the United States and other major countries such as India and China. “We can do something about this – but can we on a global level get down to below what we’re consuming now? That’s an unbelievable challenge,” Heywood says.