Filed under: Hybrids/Alternative, Green, Chevrolet, GM, Toyota
Toyota defends its defense of parallel hybrids
Earlier this month, Toyota Executive Veep Kazuo Okamoto made news when he defended his company's pursuit of further developing its parallel hybrid system called the Hybrid Synergy Drive. He was specifically calling out GM's development of the first mass market series hybrid, the Chevy Volt. On Toyota's own Open Road Blog, Irv Miller, Group Vice President of Corporate Communications, came to the defense of his boss soon after. It was an editorial we missed at the time, but reading it this morning was an eye opener.
Miller makes a case for Toyota's support of parallel hybrids by saying that at this point the Volt is vaporware, while you can buy a Prius today. He notes that Volt engineers are only able to get about 10 miles of pure electric range from current lithium-ion batteries, far short of the 40 miles promised by GM. He also goes after the set up of a series hybrid, saying, "So – and we love this part - a series hybrid hauls around a gas engine that isn't available to directly propel the car."
There are no doubt engineers in this audience who will read Toyota's response and rip it to shreds, much like commenters have already done on the original post. We'll merely respond to two points, since we're not engineers. Toyota calling a series hybrid vaporware because there isn't one on the market today is bunk. We assume the Hybrid Synergy Drive was at one time in development, too. While there's certainly a chance the Volt may never happen (10% according to Bob Lutz), the fact that GM is already using the Volt in advertising and has been completely transparent with the car's development tells us that it will do whatever it takes to bring this car to market.
To actually question the efficiency of a series hybrid versus Toyota's parallel system also comes across a bit like sour grapes. While one can argue how clean a car really is that relies on the national grid for electricity, our measuring stick for the success of a green vehicle is how little gas it uses. Sure, it's simplistic, but it not only addresses the general greenness of a vehicle from the perspective of a consumer, but also how much money it will save its owner at the pump, as well how much it will reduce this nation's consumption of oil in general. Point blank, a series hybrid's gas engine (if it employs one) is really a generator, and it's optimized to run at a constant speed with a constant load. However much gas a series hybrid does use, its generator will use it much more efficiently than the engine in a parallel hybrid that has to be powerful enough to drive the wheels.
Aside from taking issue with Toyota's defense, we also read a lot of fear between the lines, a state in which we rarely ever see Toyota. Its reputation as environmental and technology leader is under attack from all sides, and GM of all companies is leading the charge. At the moment, no one doubts the dominance of the Prius and its capabilities, but before too long the green car market will change dramatically. Not only are we promised plug-ins, lithium-ion battery packs and a series hybrid, but new clean diesel engines will be along shortly and likely achieve similar if not better fuel economy in the U.S. than most parallel hybrids. That's because we like to travel on the highways of America more than in its cities where parallel-friendly stop and go driving is standard. Diesels are more efficient at cruising speed, more so in comparable applications than any gas/electric parallel hybrid on the market today. Frankly, we can't wait to see how all this goes down in the next few years, as surely the green conscience consumer will be the ultimate winner.
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Reader Comments (Page 1 of 6)
seoultrain 12:16PM (9/21/2007)
yep, definitely hoping that GM can rub their hybrid in Toyota's face. That said, sometimes i feel like hope is all I've got.
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BLS 1:21PM (9/21/2007)
GM should note that Toyota has promised lithium ion batteries in the next Prius but has since backed down. And, I believe they have promised 100+ mpg in the next Prius, which I would call vaporware at this point.
Marc Cuomo 12:17PM (9/21/2007)
All that and the Volt looks a lot cooler too....Hope GM steps up and brings it to market sooner than later!
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why not the LS2LS7? 12:17PM (9/21/2007)
I do agree with Toyota's technical arguments about the series hybrids. Unless you want a plug-in, a parallel hybrid makes a ton more sense. But... I want a plug-in.
I've seen the Volt battery pack (prototype) on CBS' This Morning. It's more than a 10 mile pack. If you look at the 200 mile pack for the Tesla Roadster, this pack is almost half the size. Even taking into account the heavier weight of this car, it's still clear that the Volt will carry more than 10 miles of juice with it.
If Toyota wants to keep claiming their green status, they have to decide that it matters to them and take the right steps. Right now they're taking every step they can to increase sales (in their goal to become and remain #1 automaker). But since they already did well in the small/efficient car market, that means nearly every vehicle they bring out now is a new, often huge, guzzler.
Even when they do hybrids, they often mess that up. Look at the LS600hL, which gets worse mpg (according to the NYT) than the LS430 V8. Look at them taking the 2WD option off the hybrid Highlander this year. Now the only version left is the 4WD version, which costs more, takes more material to make, gets worse mpg and you're not allowed to take it offroad anyway!
Toyota, if you really want to show GM, do it the same way you did it last time, by getting your own house in order and showing your technical prowess in bringing efficient cars to the masses. The Toyota Camry V6 is a great performer and gets excellent mpg (for a large V6) so we all know you can do it when you want to.
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spw 12:19PM (9/21/2007)
yes, Toyota is fearing endless GM PR's... after an decade of PR's, GM still doesnt have full hybrid on the roads.
If you read Autoweeks interview with companies that built system in Volt, it was for show only and they didnt know what system they will end up using.
GM advertising product that might or might not be on the roads, 4 years from now, that is in very early prototype stage right now is by very definition vaporware.
But hey, GM is awesome and GM's hybrids own! lol.
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Peter 12:20PM (9/21/2007)
So – and we love this part - a series hybrid hauls around a gas engine that isn't available to directly propel the car."
Actually toyota is absolutely correct on this. From an efficiency perspective, a parallel design is superior.
Since you can drive the wheels simultaneously with both the ICE engine and electric Motor, both can be smaller and less powerful.
In a series design Both need to be more robust because the only work independently. The electric motor needs to be large enough to power the car completely. The ICE must be powerfull enough to generate all that power that the electric motor needs and you need a big generator attached to to drive provide it as well.
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Shawn 12:32PM (9/21/2007)
Peter, your assumptions are incorrect. Parallel design requires the electric motor to power the vehicle independently. Otherwise the ICE would be on all the time. The ICE has 2 jobs: Powers the vehicle as well as charges the batteries.
In series design, the ICE can now be smaller and more efficient because it has 1 job, charge the batteries. It simplies the task of each motor. Simplicity means less energy loss. GM's technology in every way is more advanced than Toyota.
cheezwiz 1:40PM (9/21/2007)
Shawn, Peter is correct. Under maximum load, both the engine and motor can power the car. To carry that same maximum load in a series system, the motor alone would shoulder the burden.
RE: energy loss, you are also incorrect. Each time energy coverts form (e.g. mechanical to electric) there is a net loss. The series requires mechanical energy from the engine to be converted to electical, the electrical to be converted to chemical for storage, and then the reverse process to power the motor and transmission. Your drive train in a series drive-train requires that all energy go through this process. With a parallel system, only some of the energy goes through this convoluted energy conversion.
Therefore, parallel drive-trains can theoretically be smaller/lighter, and more energy efficient for gasoline consumption. The benefit to series hybrids seems to be the possibility of plugging in. That may or may not prove to be a benefit in the long run.
Barney 6:06PM (9/21/2007)
Shawn you contradict yourself. "In series design, the ICE can now be smaller and more efficient because it has 1 job, charge the batteries."
It still has to haul the charger engine around. The engine may be smaller but it still weights. The only function of this extra weight, is to be an elaborate alternator.
John Dee 8:04AM (10/05/2007)
A series hybrid is a proven technology that's been used on trains for a long long time. You say the series hybrid has to carry an engine. Well, so does the parallel hybrid. If one is carrying extra weight, it is the parallel hybrid and that is the transmission which also brings extra cost. The series hybrid get it's variable speeds through the electronics of the electrical motor therefore is a better system.
Bennet Pullen 12:28PM (9/21/2007)
The statement that there are no series hybrids on the market is kind of crazy. There are no car series hybrids on the road, but there are loads of other things (like locomotives and ships for example) that use the series hybrid concept. This is proven technology; it just needs to be downsized to fit in a car.
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rem83 12:37PM (9/21/2007)
There are actually series buses on the road as well. I was able to review documents submitted to TCAT (Tompkins Consolidated Area Transit) as part of a hybrid bus contract competition, and the series hybrids were actually more efficient for that application. However, those vehicles were not meant to be used as plug-in hybrids and did not have a very large battery capacity (relative to their power consumption, anyway).
tbyron 12:58PM (9/21/2007)
There is also a company called ISE, based near San Diego, that has been selling and building series hybrid vehicles for a few years. They are mostly buses and military vehicles, frequently with Ford V10's although they can quite obviously work with other engines as well. Since the electric motors have full torque at 0 RPM, these systems give those vehicles enormous performance off the line.
sean 7:05PM (9/23/2007)
when an ICE drives the wheels directly (parallel hybrid) 20% of power is lost in mechanical drive
When ICE charges battery 20% is lost in generator,
up to 40% is lost in battery (internal resistance charging and discharging) and another 20% lost in electric motor.
No way can series compare with parallel for efficiency.
thats what toyota is talking about.
Das Boese 12:37PM (9/21/2007)
This whole "Our system is better" is just stupid. Neither system, parallel or serial, is "better", it always depends on how well it is engineered and then implemented. The interesting thing about the e-flex is that it is easily adaptable to power sources other than an IC engine, but needs an entirely new platform that is expensive to develop. A parallel system on the other hand can be incorporated into existing vehicles rather easily, using proven technology.
Toyota should try to emphasize on the strong points of their hybrid vehicles instead of lashing out at a competitor that doesn't even exist yet.
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spw 12:55PM (9/21/2007)
i think his point was "Our system exists".
:-)
Das Boese 1:57PM (9/21/2007)
Nah, I have to disagree. What he said is "Our system is inherently superior because we already build cars using it.". Which is silly ;P
AnonyMust 12:40PM (9/21/2007)
What happened to the cheek-to-cheek waltz that GM and Toyota once did. I get worried when competitors are hugging each other. Now their back in their corners. I think Toyota is starting to show its teeth. Do you think their bark is worse than their bite?
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Barney 11:00PM (9/21/2007)
"Do you think their bark is worse than their bite?"
The Japanese are like Canadians. They can also be polite while they bite you.
kballs 12:42PM (9/21/2007)
For all those that believe a parallel system is more efficient:
1. Transmissions and gears and differentials are NOT efficient. Not only do they suck up engine power, they add a lot of mass and friction.
2. An engine that has to run a wide rev range (to power the wheels mechanically) will never run as efficiently as one that can be optimized for efficiency at 1-2 rev levels.
3. An engine that has to power the wheels mechanically has to be large and powerful enough to accelerate the vehicle at a high rate when the driver wants it (puts their foot down). This is always less efficient than an engine that can just produce baseline power to charge batteries and/or maintain highway speeds.
4. At speeds under 25-30mph, engines powering the wheels mechanically eat fuel. Simply because they can't rev any lower without stalling, they use more fuel per distance than they would in a higher gear at a higher speed. Parallel hybrids often shut off the ICE at speeds below 10mph... but they still have the mechanical drivetrain adding mass and friction, which makes them a bit less efficient than a series hybrid at this speed.
5. Steady-state highway driving in a parallel hybrid may be slightly more efficient than a series hybrid, simply because of the double power conversion that the series hybrid has to go through to maintain the battery charge... but it also may be a very similar level of efficiency or even inverted in some cases, simply because the series hybrid doesn't have the mechanicals with their rotating mass and friction. A 4wd series hybrid would probably a little more efficient than a 4wd parallel hybrid in this case because of all the extra friction and mass of a 4wd mechanical system.
So Toyota is not absolutely correct on this. They are simply spreading FUD because they are afraid of how fast GM appears to be advancing their technology and how aggressively they are marketing it. It's just like the razor companies doing 3 blades, then when the other one does 4 blades the 3 blade company says "oh 4 blades aren't better, you don't really need more blades, and it's more expensive", then all of a sudden they make one with 5 blades to one-up the 4 blade company.
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