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Going the Distance

The incoming president of SAE International answers Technology Today's questions about vehicles, engines and fuels

In 2007, SAE International nominated as its new president Dr. Thomas Ryan Jr., an Institute engineer in Southwest Research Institute’s (SwRI’s) Engine and Vehicle Technology Division. Dr. Ryan, whose expertise is in fuels research, recently took time to discuss some of the factors that may shape the way vehicle and engine manufacturers balance ever-tightening regulatory limits on emissions against growing consumer demands for performance and fuel efficiency.

With oil prices going higher and emissions allowances going lower, and with electricity and alternative fuels emerging as potential solutions, what is happening to the vehicle manufacturing industry? Are we seeing a short-term problem like we did in the mid-1970s, or is this a long-term change of direction for truck and automotive engineering?

I believe that the current upward path of energy costs that we’re seeing is a long-term, not a short-term trend. It will have some ups and downs based on short-term changes in the supply-demand balance, but in general, costs will tend to go up due to the increasing costs of production and processing.

One important thing to note is that U.S. refinery output has been in the range of 95 percent of capacity for the past several years. This means that relatively minor changes in U.S. refinery output due to, say, a breakdown at a single refinery, could have a major cost impact.

In terms of their impact on the auto industry, higher energy costs actually improve the outlook for the appearance in the marketplace of more efficient vehicle and fuel options, because of the potential for rapid return on these investments by the consumer. Remember that favorable economic returns generally drive the introduction of new technology.

We are seeing the introduction of energy-efficient vehicles, like the “mild hybrids,” because consumers recognize the opportunity for overall cost savings that this type of technology makes possible. As energy costs continue to increase, vehicles containing more and more innovative technologies will be made possible and will be seen as economically feasible.

What are some of the factors that affect competitiveness of the currently known alternative fuels, given the economics of production and distribution and their effects on the environment and on the average driver’s cost-per-mile?

Most of the currently popular alternative fuels can satisfy only a relatively small part of today’s total U.S. transportation energy demand, simply because the demand is so huge. Two of the popular alternative fuels are derived from raw materials that otherwise would go into the food supply chain. Because of the very large quantities of energy used in this country, diverting these products from food to transportation would meet only a relatively small percentage of the energy demand before food prices begin to be impacted. We are already seeing this ripple effect with the introduction of corn-based ethanol. A similar trend is likely with the soy-based biodiesel fuels.

It appears that viable renewable fuels will be derived from materials that currently are not widely used in other applications. Examples include the cellulostic waste materials from the farming and logging industries. These materials can be converted to high-quality diesel fuel using the Fischer-Tropsch process, or to ethanol using processes that are currently under development. One issue is the fact that these materials are widely distributed and transportation of the raw material can have an impact on the overall energy balance.

Southwest Research Institute has conducted extensive studies on the use of Fischer-Tropsch diesel fuels and all indications are that the fuels offer both emissions and efficiency benefits in current and future engines. Ethanol is an excellent fuel for spark ignition engines due primarily to its high octane number. There are some material compatibility and energy content issues, however.

You’re beginning your term as 2008 president of SAE. How does a professional organization like SAE direct its engineering energy when the automotive industry is faced with such a wide array of technology choices? Does SAE encourage a focused approach to determine a “winning” formula and get a solution to the vehicle manufacturers as quickly as possible, or does it try to explore all of the candidate technologies and let the market decide a winner?

SAE does not encourage any particular technology but rather encourages the open exchange of information so that scientists, engineers and policy decision-makers can make rational choices based upon the best, most scientifically correct information. SAE serves the mobility industry by offering the opportunity for continual learning, literally starting in kindergarten and extending through adult-level continuing education. SAE also provides international venues for the open exchange of information in all areas related to the mobility industry.

How is SwRI directing its own engineering energy as an independent, unbiased research institution?

Similar to SAE, SwRI does not advocate any specific technology or technology path. Our charter is to provide society and industry with unbiased evaluations of available technologies. These evaluations are always based on good scientific and engineering observations and calculations. In our consortium programs, we take pride in the fact that we examine technologies that have both very near-term application as well as technologies that have higher risk, longer term applications.

To follow up on the previous question, how do consortia help OEMs decide which technology to adopt, when their members are highly competitive against each other?

SwRI currently operates two large consortia in the mobility industry. One of these is focused on developing the best available technology to replace current diesel-powered equipment, and the other is focused on gasoline-fuel equipment. Note that I did not say diesel or spark ignition, because the future engine is likely to incorporate technologies that may not be similar to today’s engines.

Because of the ever more stringent emissions regulations and tighter fuel economy requirements, our current and previous work with research consortia have indicated that future engines likely will feature very rapid combustion at lower temperatures, because we know that these combustion parameters optimize emissions while providing reasonable economy. These future engines will probably be smaller than today’s engines, but highly boosted to operate at their most efficient power output. They will involve large quantities of recirculated exhaust gas, and they also will involve higher specific power levels.

Besides engine performance and fuel efficiency, what is being done to address emissions in future vehicles and powertrains?

It is generally difficult to separate engine emissions and efficiency, and cost. The goals in our consortium programs are to develop the most cost-effective technical approaches. This means we must consider the purchase cost as well as the operating costs. In some applications, like heavy-duty, on-road truck applications, operating costs are critical. In this application, fuel consumption is critical. In some off-road applications the purchase cost is critical and fuel consumption is secondary. The best technology path varies from application to application. It should be noted, however, that the “given” in all applications is that the system must meet the prevailing emissions regulations and that the regulations are always based on “best available technology.” This effectively means that all mobility systems will have some form of exhaust catalyst system. In general, well-designed exhaust treatment systems generally improve the prevailing cost-benefit trade-off.

How much room for improvement still remains for engine designs?

Today’s heavy-duty truck engines have peak thermal efficiencies in the range of 40 percent to 42 percent. That is, they convert about that percentage of the potential heat energy contained in the fuel that they burn, into mechanical energy. Light-duty diesel engines are in the range of 40 percent and gasoline engines are in the range of 25 percent to 30 percent. Future heavy-duty engines will have peak thermal efficiencies in the range of 50 percent, with light-duty diesels around 45 percent and future gasoline engines in the range of 40 percent. The engine selection process in the future will involve choosing the solution that is the most cost-effective overall. It is also likely, however, that the diesel will always be the higher-cost selection because of the more expensive fuel and aftertreatment systems.

Is there a “magic bullet” technology out there awaiting discovery, something that will yield a clean-burning, fuel-sipping V-8 muscle car that seats six adults?

First of all, there are no magic bullets. Good science dictates the limits on efficiency of various powertrain options, as well as the energy required to move a 6,000-pound vehicle down the road versus one that weighs 3,000 pounds. In fact, vehicle weight is a key factor in fuel economy and one that will definitely be a factor in future vehicle selection. But it’s unlikely that one size, one fuel-type, or one performance class of vehicle will fit all needs. Tomorrow’s vehicles, like today’s, will be the product of the degree to which the government requires that they be environmentally clean, and the size, performance and fuel-efficiency that the consumer is willing to pay for. Consumers, after all, have different expectations of what a vehicle should deliver, whether it’s performance or payload or fuel-efficiency or clean exhaust.

If there is something like a magic bullet that can cut across classes of consumers, it may lie in the area of battery technology. Based on discussions at recent technical meetings, it is my understanding that an all-electric vehicle whose battery has a range of 40 miles will satisfy a very large percentage of U.S. commuting needs. Consumers in the electric-vehicle market look for reasonable range and rapid battery recharge. Now, if a battery were developed with a highway cruise range of 100 miles and a recharge time of, say, three minutes, that would qualify, in my opinion, as a magic bullet, assuming that it is affordable and reliable.

Published in the Winter 2007 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.

Winter 2007 Technology Today
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