The car of the future is here

Jan. 22, 2008 | When is someone going to offer a practical and affordable family car that runs on something other than oil and that sharply reduces both greenhouse gas emissions and your fuel bill? A few weeks ago, I test-drove this mythical car of the future, a plug-in hybrid electric vehicle whose mass production might be only a few years away.

The Extreme Hybrid from AFS Trinity was rolled out last week at the Detroit auto show. It can run 40 miles on electricity before reverting to running efficiently on gasoline like a normal hybrid, such as the Toyota Prius. Because the majority of people drive less than 40 miles a day, that car can replace most weekly gasoline use, even if it is charged only once a day. The fuel cost per mile, while running on electricity, is under one-third the current cost of gasoline. A full overnight charge might cost a dollar. The car accelerates like a cheetah, though quietly.

Time is running out on developing a truly energy-efficient car. Accelerated burning of fossil fuels is bringing us closer to the tipping point of irreversible climate catastrophe. We are likely to peak soon in the production of conventional oil -- so gasoline prices are inevitably headed higher in the coming decades. Meanwhile, the cars we build today stay on the road more than 15 years, so we have no time to waste.

You can buy a flexible fuel vehicle today that runs on 85 percent ethanol and 15 percent gasoline, and you might even be able to find an E85 station in your city. But corn ethanol is far from a desirable alternative fuel. It doesn't significantly reduce greenhouse gas emissions, or your fuel bill. That would require low-carbon ethanol from biomass such as switchgrass, so-called cellulosic ethanol, but the country does not have a single commercial cellulosic ethanol facility. It will probably be at least 15 years -- and possibly twice that long -- before we have large volumes of cellulosic biofuels for sale nationwide at an affordable price.

Hydrogen cars are even farther away from being practical. Carbon-free hydrogen is likely to be more expensive than gasoline for a long time. And the cost of building a carbon-free hydrogen fueling infrastructure is several hundreds of billions, if not more than a trillion, dollars.

Only one zero-carbon alternative fuel is substantially cheaper than gasoline: electricity from renewable sources (or nuclear power). Of course, you'd need a car that runs on electricity, and many people have thought that you would need a technological breakthrough, or at least a major advance in battery technology, to make that practical.

But game-changing breakthroughs in the energy sector are rare indeed. One can wait a lifetime for a major new technology that fundamentally alters the way we use energy. That's why the Extreme Hybrid, whose electric technology is available today, is so exciting.

We saw all-electric cars in the 1990s, but they failed for a variety of reasons, as explained in the movie "Who Killed the Electric Car?" One problem is that giving an electric car a 200-mile range requires a lot of batteries, which adds weight, takes up space, and increases cost. Plus, it takes hours to fill one up, so if you run out of juice, you are stuck, making it impractical as a primary family car. Ultimately, it lacked support by the very car companies, like General Motors, that built it in the first place.

Everything changed with the success of hybrid-electric cars like the Prius, which combine a gasoline engine with a battery and electric motor. These hybrids charge the battery with energy regenerated during braking or from the gas engine. They prove that a car combining gas and electric drives can be practical and affordable and even desirable. Some groups have been retrofitting Priuses to make them plug-ins, providing the best of both worlds -- acting as an electric car for local trips, but keeping the gas tank and engine for long trips and quick refueling.

The key obstacle to building a practical plug-in hybrid has been the battery. Not only do you need a lot more batteries for a plug-in than for a simple hybrid, you need batteries with substantially different capability. Gasoline hybrids mostly need batteries that can provide a lot of power when necessary -- such as for accelerating onto a highway -- as opposed to batteries that can store a lot of energy, which is what is required to go relatively long distances after a single charging. Designing a single battery that can store a lot of energy and handle power surges is no easy task, especially when that battery must be compact, affordable and safe as it constantly cycles through various uses.

The New York Times describes the problem using this unintentionally amusing mixed metaphor:

"In fact, the problem in a hybrid is not only how much energy the batteries hold, a quality called energy density, but how fast they can deliver it, called power density. The difference between energy density and power density is like the difference between a wine jug and a peanut butter jar -- the containers may have the same capacity, but the size of their openings differ greatly."

Note to NYT: When describing a power battery that can deliver energy in short, quick bursts, "peanut butter" is not the best analogy. A shaken bottle of champagne might be better.

Regular hybrids were made practical by the development of the nickel metal hydride battery, due in large part to a government-funded research consortium. The prototype or demonstration hybrids built to date have tended to use the more expensive, but more powerful and compact, lithium-ion batteries popularized by the electronics industry.

Yet discharging a battery too rapidly, especially the current generation of relatively inexpensive lithium-ion batteries such as are found in laptops and cellphones, can damage it, degrading its lifetime. The question has been: When will we have an affordable, safe, compact and long-lived lithium-ion battery that can deliver both energy (for range) and power (for acceleration) sufficient for a practical car?

Next page: How plug-in hybrids jump-start many carbon-free electricity sources