Google Talk on hybrid, diesel vehicles
Below the fold is an hour-long video of a Google talk by Reed Benet, a bio-fuels-focused Ph.D. student at the University of California Davis Institute of Transportation Studies. Much of the second half of the talk has the audience asking, where is my diesel-hybrid and why are there no diesel-hybrids? As you may know from my article on VW, I don't think clean diesel is that great. Others think otherwise.
IMHO, a diesel hybrid would get amazing mileage but it could also be a marketing oxymoron. About 33 minutes into the talk Reed says there is really no invention that puts diesel engines "in compliance" with gasoline ones. Carbon is not the only problem with fuels, just like fuel efficiency is not everything. Diesel engines are a lot cleaner than they used to be, but diesel vehicles are not perfect.
Related:
[Source: YouTube]
Reader Comments (Page 1 of 1)
eckre 9:39PM (10/10/2007)
"there is really no invention that puts diesel engines "in compliance" with gasoline ones."
rubbish, it's called BIODIESEL. 75% drop in emissions *snap* just like that.
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Bill 9:24AM (10/11/2007)
New 50-state "clean enough" diesels will sell just fine here in the U.S.
And those with a source of waste oil can make their own biodiesel for under US$1/gallon.
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Benson Leung 10:51AM (10/11/2007)
eckre :
Using Biodiesel has a number of issues. It can damage newer cars with particulate filters, and it actually *INCREASES* NOx and particulate emissions compared to regular diesel.
So, you're wrong... switching to biodiesel does not reduce all emissions... NOx and particulates get worse.
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Benson Leung 10:55AM (10/11/2007)
Bill : The 50-state clean diesels and biodiesels are two separate issues.
Biodiesels may cause issues because newer diesels (the 50 state clean ones) rely on low-sulfur diesel, and have particulate filters that may be incompatible with high biodiesel concentrations.
And even when you have 50 state clean diesels, the point of this post is that in the area of NOx and particulate emissions specifically, no diesel technology currently can make a diesel meet the strict CARB standard of SULEV, like many gasoline burning cars do today.
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Karkus 2:19PM (10/11/2007)
Actually, a hybrid diesel would be a lot cleaner than a regular diesels. Hybrids allow you to keep engine rpms more even, which means less pollution. The electric motors assists during acceleration (when diesel pollute the most) and can shut the engine off at low speed or loads (when engines are the least efficient).
Diesel hybrid is a win-win.
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bioburner 6:36PM (10/11/2007)
Benson L.: It is my understanding that biodiesel burns 70% cleaner than regular diesel-even when the catlytic converter is cold. When biodiesel is burned it produces LESS particulates than Petrodiesel. The only draw back is higher NOx production (from an emissions standpoint).
The only damage your likely to run in to using biodiesl is from the biodiesel disolving certin plastic/rubber parts in the fuel system ie fuel lines. Most diesel manufactures stopped using these kinds of products back in the mid 80s
Diesel engines-perfect no. Gasoline engines perfect no.
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Marc 6:56PM (10/11/2007)
Whether the new diesel engines will meet SULEV targets, I think we need to wait and see what appears in the spring. If you have information comparing the expected emissions for diesel cars against the SULEV standards, please provide a link so we can check it out.
Some of the emissions claims above don't match what I have seen in the technical literature. Generally, the expectation for biodiesel is a mild decrease in PM, HC and CO and a slight increase in NOx.
Here is some emissions information that comes from comprehensive literature reviews, one by the U.S. EPA, the other by researchers at the National Renewable Energy Laboratory.
For 1991-97 engines, the EPA's review of the technical literature found the following changes in emissions:
* For B20 (20% biodiesel, 80% petrodiesel): 12% decrease in PM, 2% increase in NOx, 21% decrease in HC, 11% decrease in CO.
* For B100: 47% decrease in PM, 10% increase in NOx, 67% decrease in HC, 48% decrease in CO.
Reference: A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions - Draft Technical Report, EPA420-P-02-001 (available on-line)
For newer engines, there is a paper from NREL published by the Society of Automotive Engineers that found:
* For B20 (20% biodiesel, 80% petrodiesel): 25% decrease in PM, 3% increase in NOx, no change in HC, no change in CO.
* For B100: 75% decrease in PM, 25% increase in NOx, 40% decrease in HC, no change in CO.
Reference: Dr. Robert McCormick et al., "Regulated Emissions from Biodiesel Tested in Heavy-Duty Engines Meeting 2004 Emission Standards," SAE 2005-01-2200. (not available on-line, but perhaps the results are in a report somewhere in the archives of NREL.gov, where McCormick works)
Another work by McCormick might be of interest, Effects of Biodiesel on Pollutant Emissions - A Clean Cities Webcast, link: http://www.eere.energy.gov/biomass/progs/searchdb2.cgi?9036
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bioburner 7:39PM (10/11/2007)
Marc: Thanks for the info. The biodiesel proponents usually include the 85% reduction in greenhouse gasses (for B100) when they talk about reduced "Emissions". I guess that is open to interpitation.
Based on diffrent engine type (direct injection diesel or prechamber diesel)you can get diffrent emission values which is probably why each web site seems to have diffrent numbers.
Using the numbers in comment 7 it looks like using any blend of biodiesel will reduce particulate emissions.
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akrobins 5:09AM (10/12/2007)
Ricardo PLC is developing a diesel engine to meet SULEV requirements with no aftertreatment. It is not available yet, but a demonstration model is in the works.
Ricardo is a british company that provides R&D services and technology licensing for the Automotive industry.
http://www.ricardo.com/media/pressreleases/pressrelease.aspx?page=51
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Marc 12:24PM (10/12/2007)
bioburner -- you're right that different engines have different emissions performance on biodiesel. I neglected to mention that the results I presented were for heavy-duty engines (e.g., large trucks and buses). I haven't seen similar studies on passenger cars, but also haven't looked very hard for them.
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