GM's drive-by-wire, fuel cell-powered prototype proves it's just a matter of time before zero emissions vehicles are a reality.
General Motors’ R&D Chief Larry Burns takes a seat behind the wheel of Hy- Wire, the follow-up to the Autonomy concept that debuted at last year’s Detroit Auto Show.
Last February, Larry Burns rode onto the cover of Automotive Industries on top of the Autonomy concept car's "skateboard" chassis. GM's fuel cell concept promised to reinvent the automobile, shifting all paradigms from design to manufacturing and changing the way we look at and drive cars. Burns promised a driveable version by the end of the year, and he delivered.
"We made a commitment at the 2002 North American International Auto Show to have a driveable version of an Autonomylike vehicle before the end of the year and that's what we're showing you today," Burns said during a media preview of a functional prototype called Hy-Wire. As expected, the driveable car didn't have all of the technologies featured in Autonomy, most notably using an existing electric drive system to power the front wheels instead of exotic wheel motors. "We got a great deal of interest in wheel motors. I think the industry will show a growing level of interest as well. It was just a matter of how quickly could we have the most driveable version of something like Hy-Wire.
"This is what we could do with the offthe- shelf componentry that exists in the world today." Burns adds. "What I think is impressive about Hy-Wire is that everything is packaged in the chassis that's 5 m in length. A car that has a size comparable to today's standard size luxury car." Burns says that in terms of mass, Hy- Wire is comparable to a Cadillac DeVille, even though the engineering integration to reduce mass has not been started. Like Autonomy, Hy-Wire is body-onframe construction. The body sits on an Autonomy-like platform with all of the fuel cell, drivetrain, hydrogen storage tanks and electrical components sandwiched in between the 12 in. platform.
Christoph Sheryl, manager on the fuel cell, says that GM will do all of the development on the fuel cell stacks. "The only partner we have," Sheryl says, "is Quantum, who is doing our storage tanks." "You have to control your own destiny with these technologies," says Burns. "I can't imagine a successful OEM that doesn't have its own powertrain capability. I think that holds for fuel cells and electric drive systems."
Three mid-mounted tanks hold 5,000 psi (about 5 kg) of compressed hydrogen gas which gives Hy-Wire about an 80 mi. range. Quantam has already certified a 10,000 psi tank, which in theory would double that.Driving the Future
A chilly winter wind is blowing in off the Mediterranean across the park in Frejus, France, where GM has set up a driving course for the international media to experience Hy-Wire. The unusual looking ‘future car’ draws the attention of French joggers, who aren’t afraid to stop and poke their heads inside, while engineers give us a quick lesson in driving a by-wire car. I’m a little nervous about getting behind the wheel. First of all, I don’t want to embarrass myself, fumbling around with the SKF by-wire system that looks more like a video game controller than a steering wheel. And second, I don’t want to be the schmoe who breaks this multi-million dollar one-off car. I’m fifth in line and the rest of the world is behind me. The GM engineers seem to be thinking along the same lines and decide to send us around the track in “Long Bow,” an Opel Astra with the same SKF by-wire system installed behind a diesel engine.
| Hy-Wire with no B-pillar and suicide doors, Hy-Wire opens wide for easy entry. |
The by-wire system proved to be not as big of a challenge as I thought. The handles on either side are both throttle and brake, and work independently from each other. After selecting drive you simply twist the handles backward, like a motorcycle throttle, and you’re off. You brake by squeezing the back sides of the handles, which is very natural.
Longbow has an advanced version of SKF’s steer-by-wire system. Since there’s no mechanical connection, there’s no reason for the steering wheel to rotate 180 degrees. The by-wire steering wheel only turns 20 degrees. When you’re making a 90-degree turn, you turn the wheel to full lock and the system continues to feed turn into the wheels — an unusual feeling at first, because you feel like you’re not going to make the corner. Once you get over the first initial shock, it proved easy to use, though there was noticeable understeer if you enter the corner carrying too much speed. Interestingly, the first thing I noticed as I took off in the Opel was that my feet had nothing to do and no place to go since there were no pedals. They just dangled uselessly in the footwell. It felt weird.
|Hy-Wire’s clear glass ‘grille’ offers a great view of the road. Once you get the hang of by-wire steering, it is a pleasant driver. |
Sliding in behind the wheel of Hy-Wire is easy. With suicide doors and no B-pillar, the whole side of the vehicle practically opens up. The controller is mounted to an arm that comes off of the center console. A rear-view camera is displayed on a screen mounted in the center of the controller. Cameras mounted in the side mirror position are displayed on screens mounted just inside of the doors.
Hy-Wire GM Chief Designer, Ed Welburn and his team designed the Bertone-built body that accentuates the lack of an engine in the conventional position. From the driver’s seat you get a large panoramic view out front as well as a view of the road going by through a window mounted where the grille would normally be. Hy-Wire also has an electronic foot rest. A push of a button pulls the t-shaped object towards my feet where they feel comfortably secure.
Just like Longbow, you squeeze the brake, push the drive button on the console, twist the throttle and you’re off. As expected, Hy-Wire is very quiet. The only sound you hear is the hum of the compressor. From inside it’s almost inaudible. From the outside Hy-Wire sounds like something out of a Sci-Fi movie. Hy-Wire’s steering is a little touchy and the heavier 4,100 lb. car understeers a bit in the tight right handers. But the future car works all day without a hitch.Back to Reality
While Hy-Wire proves that it can be a very practical form of transportation, there are still some hurdles to get over. Cost is a major factor. Burns admits that the cost is about ten times where it needs to be, and I think he may be a little conservative. One way to eliminate cost is through fuel cell development. Dr. Udo Winter, chief engineer — Research and Engineering, Automotive Fuel Cell Applications, says that as fuel cell research advances, a lot of the external components will be removed and the size of the cooling system can be reduced. He says that scientists are also experimenting with materi- als that can replace the precious metals that make up the fuel cell membrane. Another cost factor is materials. Burns says that the cost driver in the hydrogen storage tank is carbon fiber. The tank consists of a bladder, a carbon fiber shell around that bladder and a Kevlar shell around the carbon fiber.
“Three-quarters of the cost of the tank right now is the carbon fiber shell,” Burns says. “So we’ll need a materials breakthrough in that respect.”
Another major hurdle is the future of hydrogen storage. Sheryl says that compressed is the state-of-the-art right now. GM has no plans to go to on-board reformers. “We’re not considering reformation,” he says, “because of the massiveness of components obviously wouldn’t fit inside a 6 in. chassis.”
Burns says that compressed hydrogen is promising in that GM has been able to certify a 10,000 psi tank built to safety standards. Compressed hydrogen is also readily available today. And Burns doesn’t think it would be unusual for people to have compressed hydrogen tanks similar to propane tanks that some people have now. Compressed hydrogen can also be reformed from natural gas. “The infrastructure is in place in most developed countries where natural gas goes to most homes and most businesses,” Burns says.
Burns says that another path is electrolysis, which requires more energy, but to a country like France that has inexpensive electricity thanks to a large nuclear power network, electrolysis looks very attractive.
“If you have water or electricity or natural gas coming to your house,” Burns says, “that gives you two ways of creating hydrogen in your home. It would be the cost effectiveness of the appliance and the energy efficiency of reforming or electrolyzing that will determine whether home refueling will make sense.” Burns sees some advantages to going to liquid hydrogen.
“It’s a pretty efficient way to ship hydrogen,” he says, “because you’ve got it pretty dense and you can generate the hydrogen at centrally located high-skilled operations. The petroleum companies will tell you today that they can create hydrogen as cost effectively as they can create gasoline at a refinery. If you don’t want to have to put reformers in a bunch of gasoline stations and you want to create the hydrogen in a central site, then liquid looks pretty promising.”
The downside to liquid is that the temperature of hydrogen gas has to be lowered to –253 degrees F to liquify. The liquid hydrogen has to be kept at this temperature on-board the vehicle. GM research engineer Bob Vitale doesn’t like the liquid route “because the idea of trying to do liquid and trying to keep it that cold to be affective would be a huge energy drain on the vehicle.”
There’s also the problem of ‘boil-off’ with liquid hydrogen. When hydrogen is stored at very low temperature, no matter what you’ve done to insulation around it, there’s a tendency for a small amount to continuously boil off.
“If you drive your car every day,” Burns says, “that’s never going to be an issue because you lose very little as part of the driving cycle. But if your car was parked for two weeks at an airport you will definitely lose some hydrogen from your system.” Everyone seems to think that a solidstate hydride is the ultimate solution, though it is still very much under development. “We need to have a material that can store hydrogen such that 7 percent of the entire mass of the storage system is hydrogen,” Burns says.
A material called Sodium Alanate (NaAlH4) has shown results at around 4.5 to 5 percent in the laboratory. But Dr. Josefin Meusinger, a hydrogen storage systems engineer says that the kenetics are a problem. It takes too long to infuse the hydride and the hydrogen isn't released fast enough.
Then there's the question whether the magic 7 percent number is a necessity. With the size of today's gas tank, 7 percent will give you a 300 to 350 mi. range. "If you can fuel at home," Burns says, "you're going to top your car off every night when you come home just like you do your lap top or your cell phone." The promise of Autonomy rests on the shoulders of vehicles like Hydrogen3 and Hy-Wire. These will be the test labs for the technology that will make up the fuel cell cars of 2010.
While some of that technology may seem like wishful thinking, Larry Burns is optimistic that the vision that is Autonomy will someday be realized.
"First of all we have not backed off of wheel motors in terms of our long term vision," Burns says, referring to the unique drive system that would ideally propel Autonomy.
"In the next ten years the chassis will get thinner and someone will find a way to do the wheel motors."
Burns says that some of the breakthroughs will undoubtedly come in the motors themselves, but more important will be the integration of the wheel, brake and suspension, everything taken together as an optimized corner module system. "That's where I think we can get around the un-sprung mass concerns that people have," says Burns. "I think the real secret's going to be in systems engineering.
As opposed to any one single component breakthrough that will make that happen." SKF is busy working on making a failsafe by-wire system. Though the technology was adapted from the aircraft industry, Tom Johnstone, executive vice president AB SKF and President of the Automotive Division, admits that adapting it to the automobile changes everything. Right now redundancies are being written into the software programs and decisions are being made to determine how many redundancies each part of the system needs. The big question is what happens if there is a complete power failure. Johnstone says that there will be an onboard emergency power storage unit and unique to this kind of vehicle, as long as it's moving it can generate power.
I have driven the future, and it is here. In our lifetime we'll see fuel cells powering our businesses and our homes, and driving us to both.