BioDiesel VS PetroDiesel

[DamageINC]

I know there's a similar thread that was already created, but I wanted to more or less get one going about the major differences between BioDiesel and standard Diesel fuels. And more importantly, their effect on thigns like emissions, driveability, and fuel systems. It's never any fun to get blindsided with questions about Bio-Fuels from customers and not have any good, solid reasons why or why not to use a specific type, maybe a thread like this can help us all out....

 

I am certainly not an expert on this, by any means, so I'll just start by mentioning what I already know (or at least believe to be true.) Please - anyone with other (or contradictory) information - PLEASE chime in!

 

First, I know that BioDiesel is inherently a "weaker" fuel than normal diesel, with a lower heat value and this generally translates into lower overall power and torque production. Although, the difference is marginal and likely unnoticible in most cases.

 

I also know that it has a higher lubricity capability than standard diesel fuel, as well as (generally) a higher cetane rating.

 

I'm also told that BioDiesel is a very clean-burning fuel, with far fewer hydrocarbon emissions from the tailpipe, although NOX emissions are greatly increased as a byproduct as well.

 

Problems with Biodiesel seem to arise with the fact that it's almost too strong of a cleaning agent in the fuel system, and has been said to cause very premature failure of modern day fuel-system components. It it currently being blamed now for the de-lamination of fuel tanks in many Super-Duty vehicles, which can ultimately result in damage to (and failure of) the ENTIRE fuel system. Ka-Ching. An even more scary fact is that it can take MONTHS for a problem that has "started" from the use of BioDiesel, to actually make itself known as a driveability concern.

 

Also, I've heard that the BioDiesel "creation" process uses chemicals that remain in the fuel, and therefore allows the fuel to "absorb" and literally carry water. As opposed to regular diesel fuel which naturally seperates itself from water, BioFuel usage can take water that would normally have been seperated in a regular diesel fuel, and carry it throughout the entire fuel system. Currently, there are no fuel/water seperators in mass-produced vehicles capable of extracting water from BioDiesel.

 

And maybe, the most scary thing, is that although there is a Standard to which BioDiesel fuels are supposed to be manufactured to, I believe there is no Federal regulation monitoring the actual quality of these fuels. Nothing to regulate the manufacturing processes, materials used, or even the accuracy of the BioDiesel content in blended fuel. So just because you get BioDiesel from a gas station, doesn't necessarily mean it's of good, average, or even mediocre quality. And the actual percentage of Bio-content can vary drastically from the advertised blend percentage.

 

Storage of BioDiesel is also a big question-mark as improper storage can lead to serious issues with the quality of the fuel as time goes on.

 

BioDiesel also allows algae to grow and form in the fuel systems!

 

As of now, Ford (and MANY other OEM's) do not recommend or provide support/warranty for vehicles running anything more than a 5% blend of BioDiesel fuel. This is clearly stated in the owners manual as well.

 

I know I'm leaving some other smaller things out but I can't think of them off the top of my head.... if anyone else feels like adding something, please do! I think it's very important for us to know the pro's and con's of each fuel and what to tell customers when we're inquired.

 

Dave

[Cetane]

Although I have minimal testing experience your statements seem to be generally true. There was an SAE paper last year some time dealing with biodiesel and its effect on DPF regeneration. There were some interesting results. That test procedure yielded somewhere around a 50% reduction in HC with only a approx. 5% increase in NOx. The most noticeable finding was the discovery of a much lower DPF balance point. I believe it was somewhere around 20C lower for B5 and 100C lower for B20 on a heavy duty test cycle. Of course you run the risk of fuel system damage for the reasons you stated. It is interesting reading if you have access to SAE papers. For that matter there are a ton of studies in the SAE database relating to biodiesel and its effects on the fuel system and emissions in general.