Is Clean Diesel the Way To Go?
by Andrew Posner, Providence, Rhode Island 
on 03.21.08
We recently interviewed Alan Schaeffer, the executive director of the Clean Diesel Technology Forum, a not-for-profit whose mission is "to help people understand the value, and the progress potential, of diesel." We've also heard about ultra-low sulfur diesel and some of its benefits. With the recent announcement that VW will be coming out with a 70 mpg diesel-hybrid Golf, it seems clean diesel has hit the mainstream. However, not everyone is jumping for joy over clean diesel. A recent blog post by Jerry Garrett on the NY Times Wheels blog looks at the pluses and minuses of the technology and finds that, in the end, his "enthusiasm has been damped." See why after the fold.
For starters, he notes that many manufacturers, including Mercedes-Benz, Volkswagen, Audi and BMW are on the verge of releasing so-called 50 state compliant diesel vehicles. This means that Americans across the country will be able to benefit from the increased efficiency (25-50% compared to gasoline) and increased torque of diesel, as well as the ability to run the car on biodiesel without any modifications to the engine.
Now for the downsides. Even 50-state compliant diesels "are not capable of getting down to, say, ultra-clean SULEV emissions levels (a certification standard under California’s emissions regulations, which are the toughest to meet)." In other words, whereas diesels are about "20 percent cleaner when it comes to carbon dioxide emissions," they are dirtier when it comes to other emissions such as nitrous oxide. Another issue is that choosing a clean diesel vehicle will add "up to $2,000 to your new car’s window sticker." Of course, given that people seem to be eager to pay a premium for a hybrid, it isn't clear why the added up-front cost for a clean diesel is any different. And just as with hybrids, it can take several years before the fuel savings make up for the higher up-front cost of a diesel (although some studies have found that hybrids can pay for themselves in as little as two years with high gas prices and tax credits).
The author also claims that "diesel fuel isn’t as widely available as gasoline" which, while technically true, is misleading. According to Allan Schaeffer, as of two years ago 42% of all service stations in the U.S. had a diesel pump, and that number keeps increasing. Finally, he argues that diesel fuel is more expensive in the U.S. than gasoline, a claim that is true today, but may not necessarily be true in the future.
The bottom line is that today's diesels are clean, efficient and far quieter than they were 30 and even 5 years ago. For some uses, such as light-duty trucks, their higher torque and efficiency makes them clearly superior to gasoline. For others, the decision is more difficult. Either way, it's essential that we keep our facts straight, and remember that no matter what we drive, we can always find ways to drive less, carpool, take public transit, walk, bike or even commute by kayak!
See Also: ::Diesel-Hybrid Pickup Coming to U.S., ::Paris Motor Show: Toyota Says "No" to Diesel Hybrids and ::Instant Survey: Hybrid Hype?
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I am considering buying a new Honda Accord clean diesel, if they really come out in 2009 as has been predicted. I want to run biodiesel in it.
But I recently read this in the Wall Street Journal, and now I am having some second thoughts.
I live in Dallas, where we already have air quality problems, so I am also a bit concerned about the non-CO2 diesel emissions.
Any response from diesel fans out there?
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The Long Quest for More Miles Per Gallon
February 26, 2008; Page A17
Paul Ingrassia, in "Detroit's (Long) Quest for Fuel Efficiency" (Feb.19), suggests that any diesel engine gets 30% better fuel economy than a gasoline engine. At least half of this gain is due to the higher energy content of the heavier diesel fuel over gasoline. If liquid fuels were sold by the pound and not by the gallon, diesels would look less attractive. This is important because the bottom line is miles achieved per barrel of imported crude oil, and on this basis diesels
are not as beneficial as people have been led to believe.
Add the effect of hybridizing the gasoline engine, which largely
eliminates the throttling losses of the gasoline engine vis-à-vis the unthrottled diesel, and the gasoline hybrid and diesel are essentially identical on a miles per pound basis. Also, the popularity of diesels in Europe is because of the higher fuel taxes, which gives the heavier diesel fuel buyer an inherent tax break of about 15% over a comparable amount of energy purchased as gasoline.
Robert J. Templin P.E.
Lakeway, Texas
Lars,
I am a bit confused by your comment. Are you planning on using Bio-Diesel in this hypothetical Honda? Reduced CO2 emissions aside, biodiesel particle emissions are 20% less then petrodiesel (via Wikipedia). There is a decent amount of info on Wikipedia about Biodiesel and it appears pretty relaible and reasonable. It would seem that your concerns might be founded in NOx emissions, but that doesn't seem to have conclusive information yet and could possibly be addressed with fuel additives.
Regarding the bottom portion of your posting: The weight versus volume measurement seems a bit disingenous. Fuel is measured in gallons not weight and so fuel density doesn't really play a big role in how we view a particular fuel. Considering how fuel (gasoline, diesel) is transported, stored and used in automobiles, fuel weight seems inconsequential. I would actually say that the fact that Diesel is denser is probably a good thing as you are getting more energy out of the same gallon then you would a gallon of gasoline(that's just my lay person's view). The fact that fuel is measured by volume is the reason why Europeans favor the denser more energy rich Diesel. Also this statement about diesel vs hyrbid assumes that they are mutually exclusive.
I have some experience with biodiesel and am a fan. My tips would be to triple check whether or not your car is built to handle biodiesel (if it isn't you will find your car in the shop getting its fuel line repaired). Also if you live in colder climates you may need to mix it with petro-diesel. Oh and you may end up smelling like French Fries when you drive around.
Diesel is still a fuel and fuels can be manipulated. If maybe we had an option of harvesting our own energy, via the sun and to be able to store it on our own rather than relying on the grid and manufacturers.
But nowadays any sort of change is good.
I live in the UK and our diesel has been a low sulphur variety for years. Our supermarkets are trying to go for 5% bio-blended diesel rather than having a new pump for bio-diesel. 20 year ago we only had diesel fuel in major cities - now it's about 1/3 of all pump space in every filling station.
As for price - both our diesel fuel and cars are around 5-10% more expensive than petrol yet 40% of our new cars sales were diesel in 2007- http://news.bbc.co.uk/1/hi/business/7174856.stm.
I got my small diesel car 6 yrs ago because it would do more mpg (allowing up to 700 miles between refuelling), has a simpler maintenance routine and would be generally more reliable than the petrol equivalent - this is also true for trucks.
To see just how impressive a diesel truck can be search for: top gear north pole - yes - you can drive to the North Pole - OK not very environmentally friendly but it is possible!
Unfortunately the US is only just now entering the passenger diesel market and so we would expect people not to know about the options (and its reporting) available.
If you would have had the use of diesel options as long as us Europeans you would not want to go back to something else.
Diesel Hybrids are the better option then gasoline Hybrids as any direct test will certify in consumtion and emission.
The better calorific value of diesel and engine layout to suit the process must be the best option
I've been driving a diesel Yaris for several years and get great mpg (around 60) and it only costs £35/year to tax.
however, from a financial point of view, the growing price difference between diesel and petrol (now almost 10p/ltr more for diesel) the advantages are rapidly disappearing.
is there any real reason for this price rise, or is it just the oil companies making up for the fact we buy less fuel?
Internal combustion engines are significant contributors to air pollution, which has a damaging impact on our health and the environment and is suspected to cause global climate changes.