Driving Toward Energy Independence

I imagine driving a car without consuming petroleum, or generating pollution, or making noise. Imagine getting the equivalent of 100 to 150 miles per gallon. Imagine that every time you drove, you pumped money into the local economy, rather than sending it to distant shores. Imagine that this car was not only ideal personal transportation but also a driving force, quite literally, for transforming both agriculture and electric-power generation in ways that benefited farmers and urban dwellers alike.

Farfetched dreams? Not at all. All of the necessary technologies have been developed and road-tested in the battery-powered car, the hybrid gas-electric car, the flexible-fuel car. All that's needed is to combine these approaches in a single vehicle that merges their advantages and eliminates their shortcomings.

The hybrid car, introduced in the United States only in 2000, is already a bestseller. More than 200,000 hybrid cars ply U.S. roads. But they suffer one major limitation: They can't go more than a mile or two on electricity alone. (Indeed, GM and Honda hybrids can't go anywhere without the gasoline engine running.) This makes them glorified gasoline-powered vehicles, with an electric motor assist. But a Toyota Prius or a Ford Escape can be fitted with an expanded battery pack, rechargeable from a household outlet, that would let it travel 20 to 50 miles between chargings. That is farther than many Americans drive every day.

Driving on electric power has many benefits. Electric vehicles, or EVs, are quiet and nonpolluting. Even taking into account increased power plant emissions, EVs still produce less pollution than gasoline-powered vehicles. And EVs are remarkably efficient, achieving the equivalent of over 100 miles per gallon -- twice the mileage of the best existing hybrid.

Of course, the Achilles heel of the EV has been the cost and performance limitations of its batteries; sooner or later, most motorists want to go more than 50 miles without stopping to recharge.

A plug-in hybrid overcomes that limitation by having a backup engine -- but instead of the gasoline engines used today, it could easily be a flexible-fuel engine of the type now powering more than 4 million vehicles on U.S. roads. These engines operate on any combination of ethanol and gasoline, and the additional cost to manufacture one has fallen to about $100.

But ethanol derived from corn or other biomass also has its Achilles heel. Current U.S. gasoline and diesel consumption is far too high to replace with plant-derived fuels. Planting all available agricultural acres in the country with fast-growing trees or switchgrass could generate only enough fuel to displace about 25 percent of current vehicle consumption.

Plug-in hybrids, however, overcome this biomass limitation by using electric power to reduce fuel consumption by as much as 85 percent. This lets biofuels become primary fuels rather than minor additives.

With the introduction of plug-ins, the transportation and electricity sectors begin to merge. Utilities would probably offer EV owners the option of recharging their batteries at a lower cost at night, when demand is low. No new power plants would be needed.

Indeed, widespread use of plug-in hybrids could address the principal disadvantage of wind turbines to generate electricity -- the absence, so far, of an efficient way to store the power until it is needed. Wind is an intermittent power source, making voltage only when the turbines are spinning. But utilities need to dispatch electricity when their customers demand it.

The batteries in thousands of plug-in hybrids, connected to the grid through two-way household outlets, could bridge this gap between generation and delivery. Indeed, some studies estimate utilities might pay EV owners $1,000 to $2,000 a year for using their batteries to help balance and stabilize the grid. (That's in addition to saving perhaps $600 a year at the gas pump.)