Double Duty

Larry Burns appears pretty relaxed for a guy facing a huge task and a fast-approaching deadline.

Burns, vice president-research and development and strategic planning for General Motors Corp., is overseeing the auto maker's E-Flex project, which seeks to develop a plug-in electrical vehicle architecture that can be powered by advanced battery or hydrogen fuel-cell (FC) technology within the next two years — and do it all with an eye toward volume production and a cost equal to today's gasoline-powered vehicles.

GM has set tough targets for its E-Flex architecture: It must be mass-production ready, capable of 150,000-mile (241,395-km) durability, have a range of 300 miles (483 km) and cost $50/kW once it reaches high volumes — that's equivalent to a manufacturing cost of about $5,500 for a car similar to a base Chevrolet Cobalt.

But at a backgrounder on the FC version of E-Flex (GM earlier detailed the lithium-ion battery/gasoline engine setup used in the Volt plug-in hybrid concept unveiled at the Detroit auto show in January), Burns conveys a calm confidence that indicates he has it all under control.

“We're pretty sure at the end of 2009 we'll have a technology that can go head-to-head with current vehicles in terms of performance and cost,” he says.

“We're confident in both pathways,” he adds, pointing to the battery-powered and FC-driven E-Flex chassis and revealing that production engineering is under way on both models. “Certainly, one of these will work out.”

By design, the FC E-Flex, unveiled at the recent Shanghai auto show, is similar to its battery-powered concept. GM wants as much commonality in place so it can simply substitute power packs depending on what resonates with buyers or which fueling infrastructure is appropriate in a particular region.

That means the overall package size is the same and both can be plugged in to recharge the batteries. A 70-kW (94-hp) electric motor drives the front wheels in both cases. However, the fuel-cell model also incorporates individual 25-kW (34-hp) electric motors at the rear wheels to provide all-wheel-drive capability.

But the biggest difference is found down the chassis' spine. In the Volt, there's a small, 1L 3-cyl. internal-combustion engine up front, followed in line by a long Li-ion battery pack that runs from the front cowl to the rear wheels. A bio-fuels tank is mounted in the rear to feed the engine that acts as a generator to charge the batteries used to power the electric motor.

In the FC E-Flex, the 3-cyl. is replaced by GM's fifth-generation fuel cell, now about the size of a standard microwave oven and packaged neatly in the same space as an IC engine/transaxle combination in a conventional vehicle.

The battery pack follows, but it is half the length of one in the Volt. A hydrogen fuel tank replaces the bio-fuels tank, and a second hydrogen tank fills the gap left by the shorter battery pack.

Unlike the Volt, in which the gasoline engine is not used to drive the wheels, the FC is the primary source of power. The batteries, which at 20 miles (34 km) have half the range as in the Volt, are used here solely for an extra burst of power, similar to a turbocharger in an IC engine.

The FC E-Flex meets the target for a 300-mile range between fill-ups, GM says. The Volt claims a range of 640 miles (1,030 km).

Burns thinks the battery/IC hybrid may match up better with midsize and smaller vehicles, while the FC powertrain may have greater potential with trucks and utility vehicles.

The real breakthrough in the FC version of the chassis is the FC, itself, which Burns says leads the industry in power density. It is half the size but produces the same amount of power as the fourth-generation FC found in the GM Sequel concept and about to undergo fleet testing in Chevrolet Equinoxes.

Burns declines to reveal too many details about the FC but says it uses different materials and produces a better yield for each square-inch of cell. The power density on the new FC is 3 kW/L (by volume) and 3 kW/kg (by mass), with peak and continuous power of 80 kW (107 hp) — and GM says it hasn't reached the end of the line in terms of shrinking the FC's size and boosting its output.

“It's a system,” Burns says of the new fifth-generation cell. “The real key is in the controls.”

Precious metals are kept to the minimum, he says. “To get to a $50/kW (cost) target, you have to meet the cost target on platinum,” he says. “You need to have the bare minimum use — we're talking nano-scale coating.”

The FC's efficiency means hydrogen-fuel tanks can be half the size as those onboard GM's Sequel concept and the Chevrolet Equinox FC test vehicles, about 100 of which will undergo trials with fleet customers in 2007-2008 in the U.S., Asia and Europe under GM's Project Driveway program.

Burns says one of the toughest challenges is hydrogen storage. The tanks used for the E-Flex store 8.8 lbs. (4 kg) of hydrogen compressed at 10,000 psi (390 bar) and take 5 to 8 minutes to fill. GM has talked to other auto makers about setting a standard for hydrogen storage, and all agree they need to get on the same page when it comes to compression rates to avoid infrastructure incompatibility issues, Burns says.

Ultimately, getting the E-Flex system on the same cost basis as today's IC-powered vehicles will require volume. That won't happen overnight, Burns concedes, predicting GM could get to 100,000 units annually by the middle of the next decade, “plus or minus a year.”

“We're starting now with 100 Equinox test vehicles,” he says. “Then we'll go to thousands, 10-thousands and then 100-thousands. I think there's potential for this to reach the tipping point in terms of providing a high-volume (alternative-fuel transportation) solution.

“Then we'll be able to make capital decisions. Do we tool up for a new V-6 engine or this? There's a chance in the 2015-2018 timeframe to show whether this is possible.

“We don't think we can sell this vehicle if it costs more,” Burns adds. “And we can't have the effect we want on the environment if we don't sell a lot of them.”

Development of E-Flex doesn't mean GM is abandoning the skateboard-like platform that underpins the Sequel concept. The auto maker is following both paths, Burns says, with the E-Flex aimed at working within existing vehicle architectures and the skateboard system exploring how vehicle designs could be optimized with the new technology.

The E-Flex-based Volt, at 3,500 lbs. (1,588 kg) is 30% lighter than the Sequel. The Volt uses molded plastic for its fenders, window glazings, instrument panel and steering wheel that cut weight 30%-50% per part, GM says.

The cost of the E-Flex system, whether battery- or FC-driven, will be kept in line with today's vehicles in part by a considerable reduction of parts — one-tenth as many moving parts as in a combustion engine propulsion system, Burns says.

Cost of operation also will be favorable. In the case of the FC, Burns offers one scenario in which hydrogen, at a cost of $3.50 per kg, translates to 4.7 cents per mile (1.6 km). That compares to 8 cents per mile with gasoline if priced at $2.40 (including taxes) per gallon (3.8 L).

In the end, the biggest hurdle may be in the re-fueling infrastructure, but here, too Burns shows confidence. It would take $12 billion — half the cost of building the Alaskan oil pipeline today — to put up enough hydrogen fueling stations to service 70% of the U.S. population, he says.

“People have to take the infrastructure thing not as one step but as a sequence of steps,” he says. “And we have to grow the number of vehicles as we have the infrastructure in place.”

GM unveiled the FC-powered E-Flex in Shanghai because it believes there's potential for electric-powered vehicles in China, where the car market is still emerging and an oil-based infrastructure still developing. Burns says he has met with Chinese officials to discuss electric vehicles and has taken the mayor of Shanghai on a test drive in the Sequel.

GM engineers say to stay tuned on the E-Flex, as more will be rolled out at the Frankfurt auto show this fall. That likely means the unveiling of an additional body style different from the Volt concept. On a graphic shown to journalists highlighting the E-Flex is a sketch of a small cross/utility vehicle.