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Biodiesel’s Beneficial Effect on Diesel Particulate Filter Performance

Use of biodiesel can lower the balance point temperature in diesel particulate filters (DPF) compared to Ultra Low Sulfur Diesel, and can cause a measurable increase in the regeneration rate of the DPF, according to data from the first phase of a study by the National Renewable Energy Laboratory and Cummins presented at DEER 2006.

The balance point temperature (BPT) is the temperature of the DPF at which the amount of soot that is accumulating in the filter equals the amount that is oxidizing off. If the BPT is lower than the general exhaust temperature, then no active regeneration is needed to clear the filter. Conversely, if the BPT is higher than the general exhaust temperature, active regeneration of the filter—an artificial, higher temperature burn—is necessary.

The researchers found that the BPT was lower by 45° C for a B20 blend and by 112° C for B100, compared to ULSD fuel. They also found that the measurable increase in regeneration rate of the DPF was not accompanied by significant differences in NOx emissions, which suggests that inherent differences in soot reactivity are primarily responsible for the observed differences in BPT and regeneration rate.

The team characterized the soot from the various fuels by a variety of methodologies, and found that use of biodiesel produces a much more disordered soot structure containing higher levels of oxygen, and that the soot for biodiesel fuels is much more reactive in oxygen than diesel soot.

By not only validating the compatibility of biodiesel blends with advancing aftertreatment technology but by also showing a benefit, this work paves the way for wider adoption of biodiesel blends in on-road heavy-duty diesels. Such vehicles are required by the 2007 particulate emissions standards to use DPF technology.

This first phase of the study was using steady-state conditions, and a 2002 engine certified to 2004 emissions levels. The second phase will move to a 2007-compliant engine and aftertreatment system, and test under transient conditions.



Very, very nice. The emission benefits of biodiesel just get better.

allen Z

Biodiesel blends (B5 through B20) also help with lubricity. This reduces frictional losses in the cylinder. Therefor, biodiesel is a beneficial additive, and fuel.
___Now, how to tackle NOX. Supply would likely come from oil crops like soy, cottonseed, or rapeseed/canola. Waste oil/animal fat to biodiesel is another source. However, the long term prosepects would be better with algae derived fuels.


I've been saying for years that biodiesel is the way to go, at least in the short term.


How about 7% ethanol (1 % blending agent), 20% biodiesel, and 72% ULSD?


How about logical emissions standards which allow the light duty diesels currently banned from 5 states? How about those standards also be applied to heavy duty diesels which outnumber light duty by several orders of magnitude, yet are exempt from the current light duty standards.

How about giving efficiency and CO2 at least equal importance to particulate and nox?

Oh, then we'd have a load of great, long-lasting, lower maintenance, 30% more fuel efficient vehicles that are able to run on home-brewed fuel made out of french-fry juice. And we'd also have trucks and buses that don't belch clouds of black soot every time they accelerate.

Can't have any of that now, can we!


The effects of particulates can be seen immediately, CO2 takes more time for its effects to become apparent. Makes it easier for the general public and politicians to address particulates right now and push CO2 issues off for "another time".

Before everyone starts "home brewing" fuels the ecological impact of this should be evaluated. The people home brewing out of environmental concerns may not be a problem but those who would do it to save a buck may not care how much of a mess they may (or may not) make. Standards should be set up for a safe method to home brew fuels and before you sell fuels to your neighbors appropriate licensing and inspections should take place just as they should for any refiner of transportation fuels.

I think a "logical" emission standard to be put in place would be to have all vehicles, regardless of technology, follow the same emissions guidelines...they have only one fuel economy standard so there is no reason to have more than one emissions standard.

Just imagine...instead of a "carbon tax" if they instituted rationing. You get 600 gallons of transportation fuels per year at normal prices. Every gallon afterwards requires a $1 per gallon "gluttony" tax. Everyone would flock to more fuel efficient vehicles and the rich who choose to buy wasteful vehicles can pay the taxes for it...people will stop enroaching on the wilderness to live in a house 50 miles away from their workplaces. At 20mpg you would only be able to drive 12000 miles without paying excessive taxes but if you live within 10 miles of your workplace that is completely reasonable (5200 miles for work driving and then an extra 6800 miles for all other driving in the year). Buy a car with 30mpg average and you could drive 18000 miles without paying excessive taxes. Buy a vehicle that hits 45mpg (hybrids, small diesels) and you can do 27000 miles without incurring excessive taxes. Seems reasonable to me.


Why stop the incentive at 600 gallons/year?  Just tax all fuel and rebate the tax evenly as a flat deduction on FICA.

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