| Subject: Path to hydrogen splits engineers |
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Betty
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Date Posted: 16:07:53 09/05/05 Mon
Path to hydrogen splits drive train engineers
Within the next 20 years, petroleum will become scarce enough — and expensive enough — that a hydrogen-based energy infrastructure will be needed. A spirited panel of automotive power train and electronics experts at last Monday's Infineon Technologies Media Day here had little trouble reaching that conclusion.
But how to make do until that infrastructure is in place proved a tougher nut to crack.
Virtually the only point on which all agreed was that any solution will require a wealth of high-end electronics.
Improvements to current engine technologies — gasoline internal combustion, diesel and hybrid drive trains — will be needed to stretch dwindling hydrocarbon fuel resources until an alternative is ready, panelists said. Industry inertia and buyer indifference, however, are limiting factors. At least, that was still the case on the day of the conference, as the killer hurricane Katrina bore down on the Gulf of Mexico, assaulting the region's shuttered oil refineries and hobbling that critical capability to an extent that won't be fully understood for some time.
"We have only 20 years of proven oil reserves in the world today," warned Karina Morley, director of power train control electronics at Visteon. "And yet change will come very slowly. The power trains for the 2009 model year are already under contract, and I can tell you that they are almost entirely based on internal-combustion technology."
That's partly because consumers haven't yet been clamoring for change. "Energy efficiency in internal combustion engines could be improved by 5 to 10 percent now," Morley continued. "But, frankly, fuel efficiency is not even among the top 10 factors for automobile purchase decisions," though it does make "the top-five list of owner dissatisfaction items."
Part of the reason for efficiency's low-priority status has been "the [low] return on cost," Morley acknowledged. "Even at today's gas prices, the difference between the best mileage and the average in most [automotive] classes amounts to about 4 cents per mile. At that rate, it takes 100,000 miles or more to repay the incremental costs of more efficient drive trains. On that basis, consumers won't buy it."
And yet designers are pursuing those incremental increases in efficiency with a will.
The main areas of research today, the panelists said, fall into two camps: new combustion technology and hybrid drive trains. Stumping for those respective strategies at the panel session were John Pinson, group manager for diesel engine research at General Motors, and David Hermance, executive engineer for advanced technology vehicles at Toyota.
Toyota's hybrids couple a large electric motor with an Atkins-cycle gasoline internal-combustion engine. "By the end of 2005, there will be 500,000 hybrid vehicles in the world, half of them in the U.S.," Hermance said. "We are targeting production at 1 million units per year by 2012."
The goal with hybrids is not to sell consumers on an entirely new, high-efficiency type of car but to improve the efficiency of the cars the public already wants. "It's an emotional decision," he declared. "U.S. customers don't value efficiency, and they won't accept compromises in the things they do value — performance and comfort — in order to get it. But they will pay for performance.
"Hence, we are in the process of seeking a balance between increased efficiency and increased performance that the broad market of U.S. customers will actually buy."
In contrast, GM's Pinson described three initiatives that, in his words, amount to the reinvention of the automobile. One seeks to improve internal-combustion efficiency, another to hybridize drive trains and yet another to create an entirely new drive train.
Pinson's description of the first initiative, the search for more efficiency, stirred the greatest interest. He described work on the Homogeneous Charge Compression Ignition (HCCI) engine, a concept that looks to improve fuel economy in gasoline engines by 20 percent and to allow diesel engines to achieve emissions comparable to those of gasoline engines. The engine can also be hybridized for even more efficiency.
GM and Bosch, along with Stanford University, have a joint program to unable HCCI technology through development of advanced control systems involving sensors, actuators and algorithms.
The HCCI process does not use a spark for ignition; rather, much like a diesel, it relies on heating from compression. But the technique can be used with a wide range of fuels, including diesel or gasoline. When properly controlled, Pinson said, the ignition within the cylinder is so uniform that there is no flame present. That leads to high energy-to-pressure conversion and low emission of combustion by-products.
"The challenge is that the process is inherently unstable and difficult to control," said Pinson. But he added that currently available technologies — such as direct fuel injection and variable valve timing, together with sensor-rich, very high-compute-power microcontrollers — will be adapted to make HCCI engines work.
External conditions, such as air pressure and temperature, head temperature and fuel quality, influence the evenness of combustion in an HCCI cylinder, Pinson elaborated. It's therefore necessary to monitor the input variables continuously, as well as to monitor the quality of each ignition by running the control algorithm for each charge released into a cylinder.
Ignition quality, Pinson said, can monitored by means as simple as digitizing the output from the ordinary acoustic knock sensor that is used in today's production gasoline engines — or by techniques as complex as locating a pressure sensor in each cylinder. "We are currently engaged in research to determine how elaborate a closed-loop control system we need," he said.
"You have several variables to control," Pinson continued. With direct injection, fuel can be delivered in carefully timed spurts; today's lab engines have as many as five discrete injection events during a cycle. With variable valve timing, the amount of exhaust gas left in the cylinder at the completion of the previous exhaust stroke can be controlled: To increase the cylinder temperature, leave in some hot gas; to cool the cylinder, make sure all the gas flows out.
"But you have to do these computations and make these adjustments on each cycle," Pinson said.
The upshot for chips
Christopher Cook, vice president of the Automotive and Industrial Division of Infineon, illuminated the implications for semiconductor vendors.
"Whatever route we take, there will be increased complexity and increasing use of closed-loop control systems," Cook said. "That means the industry will need higher processing power; more — and more varied — I/O capability; advanced sensing technologies; and advanced smart power for such things as valve actuation or control. HCCI, for instance, is one of the most-complex control architectures we have seen."
That complexity will influence not only the solutions but the supply chain, Cook said. "It isn't enough to supply components now. For systems like these to come together, every organization in the supply chain must understand the whole system."
In a question-and-answer session, Hermance and Pinson continued to spar about whether HCCI, hybrids or some combination of the technologies will win with consumers. Both pointed to the looming 2007 U.S. emissions standards, which for the first time will be fuel-neutral: All engines, regardless of what they burn, will have to meet the same emissions strictures.
Hermance said he's skeptical that diesels, even with HCCI, can make the cut under the new standards at a reasonable cost, particularly in the light-vehicle market. But he admitted that there's no battery technology on the horizon that might deliver the hybrid drive train from its primary dependence on its continually starting and stopping, emissions-producing internal-combustion engine.
When presented by a questioner with a vision of a primarily electric vehicle that would only use internal combustion a last resort, Pinson replied, "The closest thing on the drawing board to that vision isn't some evolution of the hybrid drive train. It's a fuel-cell vehicle.
"That is where we eventually need to go," Pinson added.
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