Diesel Hybrids May Face Substantial Cost Barriers - Reuters

[hatrack]

FRANKFURT/TOKYO - "A car that can go 80 miles on a gallon of renewable fuel such as soy and canola would seem like an ideal solution to oil prices bumping around historic highs of $50 a barrel.

In fact, the technology already exists in the form of so-called diesel hybrid vehicles, which yoke a conventional diesel engine to an electric motor and battery to store unused energy for clean and quiet driving at lower speeds. But automakers say such cars are unlikely to move out of the research lab any time soon, even as fuel efficiency becomes a must for more and more customers appalled by prices at the pump.

The main problem is that diesel hybrid cars cost too much to produce - thousands of dollars more than petrol-electric hybrids like Toyota Motor Corp's (7203.T: Quote, Profile, Research) Prius, which is a sell-out U.S. hit. "Diesel hybrid is one possible propulsion system that we are researching and testing, but no one can say whether this is the path to the future," said Edith Meissner, a spokeswoman for German-American carmaker DaimlerChrysler (DCXGn.DE: Quote, Profile, Research) .

EDIT

But this lands a double whammy on costs. A diesel engine typically costs around 10 percent more than its petrol-driven cousin of similar power, even without the cost of adding an electric motor, batteries and the electronics to run them."

EDIT

http://www.planetark.com/dailynewsstory.cfm/newsid/27622/story.htm

[phantom power]

1. Does anybody out there understand why this would be true?

The article doesn't really give much in the way of explaination. I'm trying to imagine why a diesel would be harder or more expensive to integrate with an electric drive than a gasoline engine, I'm coming up blank.

[hatrack]

2. As I understand it, basic engineering & unit costs are higher for diesels

To begin with, you have to have a somewhat more massive block to hold up to the stress of diesel compression - which is about 20:1, compared with 9.5:1 in a gasoline car.

The fuel-injection systems for diesels are extremely complex, partially because that's the nature of the beast, and partially because of emission requirements, at least for diesel engines in passenger cars (it's somewhat different for diesel systems in commercial trucks, etc.).

On top of that, since American oil companies sell mule piss and label it "diesel", and lower-sulfur fuel similar to what Europeans use isn't going to arrive here until around 2007, there's added engineering which will allow passenger diesels sold here to meet EPA Tier 2 standards.

[phantom power]

4. But why does that make it harder to use in a hybrid?

is it just because the extra stuff leaves less room for the electrical drive?

[hatrack]

5. Not technical problems per se, just added costs

All the stuff I listed adds to the "base" cost even before you start synching up with the hybrid drive system and its attendant computers & subsystems.

[TommyO]

3. Straight diesel engines...

are more expensive than the gasoline engines stuffed into small cars. A VW Diesel adds about $1000 to the cost of a Jetta, Golf, or New Beetle, add the electric-hybrid portion of the package and you're talking a major up-charge for a diesel-electric hybrid.

[cprise]

8. They are less expensive on cost of ownership

...which is why Consumer Reports have been awarding high marks to the VW TDIs. For $1000 up front you get a car that can save loads of money on fuel, is more durable than its gasoline counterparts, and also holds its resale value better. Also, this additional up-front cost has been lowering over time as economies of scale increase.

The economies of scale at work in diesel-hybrids is currently near zero, so the price difference cited in the article is no different than the canard from 5 years ago that gas hybrids would carry a whopping premium.

[Xithras]

6. You also have the glow plug issue

Gasoline engines can be started and stopped nearly instantly because they fire as long as you have gas and spark. Diesels have glow plugs that can delay starting by 3-30 seconds, depending on the outside weather. Because hybrids need to start and stop their engines with some frequency depending on driving conditions, acceleration, and speed, this delay can become a major problem.

I've only seen one solution to this on paper, and it involved equipping three glow plugs per cylinder and constantly rotating the "hot" plug while the electric motor was engaged. While this trick allowed the engine to fire quickly, it introduced all kinds of peripheral problems ranging from weakening the cylinder head to increasing production and maintenance costs for the vehicle.

[phantom power]

7. Actually, I figure a hybrid would *help* with that:

a hybrid can run purely on batteries, for the first several minutes at least. So, that allows time for the engine to heat up.

[cprise]

9. Glow plugs exist to ensure a minimum cylinder temperature

...when cold-starting an engine. I can ignore the glowplug delay any time I want on my VW when the engine is warm (which an auto engineer can certainly take into account). When I don't ignore it, the glowplugs stay on for less than a second when the engine is warm, and by 'warm' I don't mean just full-operating temp-- I mean anything above the 'cold' 1/4 mark on the temp gage. When the engine is cold, in cold weather, the delay is 6 or 7 seconds. I do think a hybrid that has stopped at a traffic light is capable of moving a car forward for 7 seconds before the combustion engine starts.

This should not be an issue for a late-model, TDI-type passenger car engine. VW already uses an automatic start/stop procedure in its non-hybrid diesel Lupo TDI 3L to help it acheive over 75MPG US.

[ohio_dem_52186]

10. Hey fellow diesel-lovers. My first visit to this DU forum...

After a direct injection diesel (i.e. a modern one) gets warmed up, it no longer needs it's glowplugs. I actually do diesel engine testing and I don't even use the glowplugs since I always start at room temperature in the lab.

Automakers have succesfully built diesel HEVs, but I think they came to the same conclusion that you did with the cost being a bit to pricey for the benefit. Several Univeristy teams built diesel hybrids for the DOE sponsored FutureTruck Competition:
www.futuretruck.org

One of the reasons that gasoline engine's hybridize so well is that they have lousy efficiency at part load operation. By downsizing the engine, you effectively shift the operating point to higher efficiency operating point. You stand to gain a lot.

With a diesel, your engine efficiency is not nearly as bad at the mid-low loads like a gasoline engine is. So when you hybridize, you don't get as much benefit for the same added cost.

[NNadir]

12. In what capacity do you test engines?

I would be very interested in learning more about the chemical composition of seals, particularly organic materials, used in diesel engines. Even better, a description of the range of such materials that have been explored either experimentally or industrially would be most interesting.

If you could steer me in the right direction, it would be most appreciated. Thanks in advance for any advice you can give.

[theoceansnerves]

11. what about for larger applications?

the transit authority here (OCTA) has been running two diesel-electric hybrid buses as part of a test program for a couple years. surprisingly(?) they are manufactured by GM.

i can't find anything too recent about it, but here's an older article
http://www.govwest.com/urbanbus_tran.asp