NOVI, MI – Alternative-powertrain development is key to lessening U.S. dependence on foreign oil and reining in greenhouse-gas emissions, but coming to a consensus on what form these new technologies should take proves difficult during a panel discussion at a conference here.

Lithium-ion batteries are the basis of many alternative-powertrain programs, including next-generation hybrid-electric, hydrogen fuel-cell and pure-electric vehicles. But not all auto makers view Li-ion technology as the next step toward the electrification of the automobile.

Jaycie Chitwood, Toyota Motor Corp. senior strategic planner, advanced technologies department, says nickel-metal-hydride batteries used to power today’s hybrid-electric vehicles are critical to the auto maker’s product plans going forward.

“NiMH is not yesterday’s news; they’re going to be the core of our hybrids for years to come,” Chitwood tells the Automotive News Green Car Conference. “We believe there’s still plenty of opportunity to improve upon them. There will be a place for Li-ion, but it will not be the dominant battery application.”

Before Li-ion can be made viable for production use, there are obstacles to overcome, including cost and power-density issues, Chitwood says, adding Toyota is working on different battery chemistries that she declines to reveal.

David Vieau, president and CEO of battery developer A123 Systems Inc., says issues surrounding Li-ion batteries are being solved, and the technology is on its way to becoming affordable enough for mass production.

Key to bringing down the cost and increasing the energy density is reducing the amount of ancillary technology in a Li-ion battery pack.

“A battery system today is made up of 30% system elements and 70% cells,” Vieau says. “If we can reduce the cooling requirement (by making) the cells less sensitive to temperature and the environment, they will cost less, because we won’t need as much overhead content.”

Li-ion batteries will play a role in Ford Motor Co. powertrains, but most likely only in certain situations, says Sue Cischke, Ford group vice president-sustainability, environment and safety engineering.

“You’re going to see electric vehicles, but for very specific purposes,” Cischke says, noting that cars built for city driving would be an ideal fit for electrification.

For longer commutes “liquid fuel is going to be around for a while,” she says.

Chitwood echoes Cischke’s sentiments. “Future electric vehicles will be purpose-built, they’re not going to be for the average consumer group.”

Cischke says Ford also is exploring applications for Li-ion batteries after they are no longer viable for vehicles. Possibilities include using the cells to help power homes and forming partnerships with electric utilities to integrate the batteries into the power grid.

“It’s all about how to commercialize the battery to get the cost down,” she says.

Meanwhile, Cischke defends Ford’s strategy of developing smaller, more fuel-efficient cars for the U.S. market, despite the fact fuel prices are declining rapidly.

“We’ve seen this movie before,” she says, adding Ford sees a “fundamental shift in segments” as consumers turn away from larger vehicles in lieu of smaller ones.

“We’ve looked very closely with all that’s happening with the economy and we’re confident that we made the right choices, and we’re comfortable with where we are,” Cischke says.

While Toyota made short-term adjustments in its production plans to accommodate demand for smaller cars when gasoline prices eclipsed $4 a gallon this summer, Chitwood says the auto maker does not believe there has been a permanent shift in the U.S. market.

“I’m not sure people have fundamentally changed,” she says. “Small vehicles only work for a certain lifestyle and certain living environments. I think it’s a temporary shift.”

As such, Toyota wants to maintain flexibility at its assembly plants in order to adjust production quickly from small to larger vehicles depending on consumer demand.

Ultimately, the U.S. will be overshadowed by those of emerging markets such as Russia, India and Eastern Europe, says BorgWarner Inc. CEO Tim Manganello.

“The U.S. market is relatively flat, future growth is going to be in (emerging markets),” he says, noting fuel prices elsewhere in the world remain high.

“So gas prices in the U.S. don’t mean anything, because it’s a flat market,” Manganello. “If you want to grow in the industry, you have to grow globally and you have to have small, downsized engines with more fuel-efficient powertrains with less parasitic losses.”