Green by Design
Part 7: Greener Tech Tomorrow

The hybrid vehicles now on the market and soon to be introduced are the infants in a "baby boom" of next-generation automotive design. Increasing electronic smarts as well as a move toward drivetrain electrification are just some of the traits of this new wave of technology. As seen in the Honda Insight, Toyota Prius, and other pioneering models, other traits of the new generation include extra-efficient and super-clean engines as well as advances in materials and vehicle structures. A key factor is that greener tech tomorrow will encompass many innovations, not just a single "silver bullet."

Big strides in efficiency can be made by cutting vehicle mass through the use of lighter, high-strength steels, lightweight metals such as aluminum and magnesium, and advanced plastics and composites. An aluminum-based structure, as used on the Audi A8 or Honda Insight for example, cuts weight substantially compared to standard stamped steel body while improving rigidity and crashworthiness.

An important opportunity is the prospect of building lighter-weight SUVs. Safety as well as environmental concerns dictate that the heaviest vehicles need to lose weight first and most. Ford recently built a research fleet of aluminum-based midsize cars that tip the scales at 2,000 pounds, 40 percent less than today's typical 3,300-pound curb weight. This degree of weight reduction improves efficiency no matter what kind of engine is used and makes hybrid drivetrains more affordable.

The internal combustion engine still has some years of improvement ahead. Advanced engine technologies abound. Variable valve control—in which the timing of cylinder intake and exhaust valves varies to improve emissions, efficiency, and performance—is exemplified by Honda's VTEC (first introduced in 1989), Toyota's VVT-i, BMW's VANOS, and GM's cam-phasing VVT. Optimized versions of this engine refinement offer up to a 10-15 percent efficiency boost while aiding emissions control. A host of other techniques exist for reducing energy-wasting friction, cutting the weight of the engine and its accessories, and improving air induction. A combination of cleaner gasoline, advanced catalysts, and electronic controls can cut gasoline engine pollution to near-zero levels.

Charging Forward

Although we have not seen pure electric vehicles (EVs) on the market for a couple of years, an interesting variant on them may crop up in the not-too-distant future. So called "plug-in hybrid electric vehicles" (PHEVs) combine the emissions and oil reduction benefits of all-electric travel with the limitless range of hybrids. The idea behind PHEVs is that they would operate for a given range (anywhere from 20 to 60 miles) as electric vehicles and have the ability to recharge using the electricity grid. If they are driven distances farther than their electric-only range, the gasoline engine would kick in, becoming in effect a regular hybrid-electric vehicle. While the idea is intriguing, at this time only a few test models have been produced, and no OEM has announced plans to mass-produce such a vehicle. One reason for this caution is that the viability of PHEVs hinge largely upon the performance and cost characteristics of the vehicles' battery packs.

Long the Achilles heel of electric vehicles because of their high cost, relatively short range, and long recharging times, batteries have in fact seen improvements over the past few years. Today's nickel-metal hydride batteries have greater durability than previously expected, meaning a replacement of batteries during the course of a vehicle's life may not be necessary. On the other hand, cost continues to be a challenge for all battery types in general, and especially for types used in vehicle applications.

Battery needs in EVs, HEVs, and PHEVs can be quite different from one another. EVs and PHEVs require "high-energy" batteries, capable of providing constant energy source for a sizable period of time, while HEVs require "high-power" batteries, capable of providing short bursts of boosting power. "Intermediate-power" batteries that bridge the gap between these two types may in time prove most viable for PHEVs, though they are still under development.

Batteries have been produced using a wide range of materials. Lead acid and nickel cadmium (NiCad) batteries, for example, have seen broad use in numerous markets. At this time, two types of batteries show the greatest market potential in electric drive vehicle applications. These are nickel-metal hydride (NiMH) and lithium-ion (Li-ion) batteries. Nickel-metal hydride batteries are currently being used in all of today's HEVs and a number of recent OEM EVs. The performance characteristics of lithium-ion batteries show promise, although their cycle life and calendar life durability have yet to be proven. As a result, it is expected their market potential will lag that of NiMH batteries by a number of years.

Battery sizes in electric drive vehicles also vary dramatically. A typical HEV battery pack contains approximately 3 kWh of electricity, while a pure EV contains nearly ten times that amount. PHEV battery requirements depend on the design of the vehicle, with PHEVs with 20 mile ranges in the vicinity of 6-8 kWh. These design requirements will have a significant impact on an electric-drive vehicle's cost. Depending on how cost and durability issues with these advanced batteries pan out over the next few years, it's possible we may see the reemergence of electric-drive vehicles.

Fuel Cell Vehicles

Looking farther down the road, perhaps the most promising "Greener Tech" of tomorrow is the fuel cell. Fuel cells are like batteries in that they convert chemical energy directly into electricity. But they have the big advantage of being able to do this from an onboard fuel, ideally hydrogen. Fuel cells have powered space missions, and recent research breakthroughs have cut their costs enough that down-to-earth uses now look plausible. Fuel cell buses have already been demonstrated in actual transit service. A number of automakers now have fuel cell vehicles in demonstration fleets.

However, it is unclear if and when fuel cell vehicles will become widely available. Part of the reason is that costs still need to drop considerably. Also, a lot of new engineering is needed to make the components of a fuel cell engine work reliably in the challenging confines and changing conditions experienced by cars and trucks. Even if the necessary breakthroughs occur and good engineering progress is made, it will probably be 20 years or more before fuel cells become viable for truly mass-market cars and light trucks.

Perhaps the biggest barrier is getting the right fuel to the cells. Nearly all fuel cells, and particularly those that would work well in vehicles, need pure hydrogen gas to operate. Hydrogen is difficult to store, and widespread distribution for it does not exist. Car companies are exploring more convenient fuels, but these add cost and complexity to the fuel cell powertrain while detracting from its efficiency. Buses present a better near-term opportunity for fuel cells, since they have more onboard space, can fill up at depots, and tolerate higher costs than automobiles.

Hooking up to alternative fuel supplies and converting various fuels to hydrogen are much lower barriers to the use of fuel cells in stationary electric power generation and even small electronic devices. Cost hurdles may also be less severe in non-automotive applications. So, fuels cells may be providing electricity to offices and factories some years before they become common under your car's hood.

Green buyers should be cheered by the fact that low-pollution piston engines still have great potential in the years ahead. Improvements in bodies, interiors, engines, and transmissions, along with the added benefit of hybrid drive, promise a steady stream of efficiency gains and pollution reduction from gasoline cars and trucks. Such progress can benefit the health of both people and the planet at relatively low cost, and sooner rather than later. In short, much of the "Greener Tech" we need tomorrow is already somewhere on the road today.