Hybrids to Remain Viable as Future Powertrain Enabler

Special Coverage

SAE World Congress

DETROIT – Although hybrid-electric drivetrains currently occupy bit-player status in the overall market, continued developments will secure their future as a core technology for all future powertrains, a group of experts concludes.

Raised during a panel discussion at the recent 2007 SAE International World Congress here, the issue centered on the viability of hybrids in the future automotive marketplace.

“Despite the recent downward trend (in sales), hybrids continue to improve (in terms of price and performance),” Don Hillebrand, director-Center for Transportation Research, at the Argonne National Laboratory, says, noting there is compelling government interest in hybrid-electric vehicles (HEVs) because of their potential for long-term fuel savings.

HEVs and full-electric vehicles have been around since the dawn of the automobile, yet, their widespread proliferation has been hampered by relatively high costs and significant advancements in competing powertrains such as clean diesels.

“Hybrids are not perfect, but we (the automotive industry) can’t wait for a magic bullet,” says Martin Klein, engineering director-Compact Power Inc.

“(Hybrids) are the best solution now on the table and demand urgency (in development).”

That development currently revolves around lithium-ion batteries and their associated power electronics, both of which are key drivers of HEV price, performance and range.

Li-ion batteries are comparable in cost to conventional nickel-metal hydride systems, which currently make up about 5%-10% of the total cost of HEVs, Klein says, noting batteries will comprise about 15%-30% of the cost of upcoming plug-in HEVs (PHEVs).

Of note are recent concerns regarding sufficient amounts of lithium available to support a growing hybrid market. But Klein says that will not be an issue.

“There currently is about 7 billion kg (15.4 billion lbs.) of lithium available,” he says, “enough for about 33 billion HEVs or 6 billion PHEVs.”

Ramping up volumes of Li-ion battery systems will be key to reducing costs, as will continued innovation through shared development efforts between battery suppliers and OEMs, says Andreas Truckenbrodt, executive director-Hybrid Powertrain Programs, DaimlerChrysler AG.

In addition, greater communication between the industry and policy makers will improve HEV viability, while cooperative business models, such as the Two-Mode rear-wheel-drive HEV program between DC, General Motors Corp. and BMW AG, will accelerate hybrid system development times.

“Hybrids are a backbone technology, paralleling the road map of future powertrains and working with all future (drivetrain) technologies (as an enabler),” Truckenbrodt says.

Other factors critical to the success of hybrids include proper integration within the vehicle, reduced system weight and improved packaging and reliability.

On the subject of PHEVs, which several auto makers already have announced are part of their near-term product plans, Truckenbrodt warns about stretching development efforts too far.

“Plug-ins have great potential, but promises must be turned into deliverable products because the customer decides the success of new technologies.”

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