Date:         Thu, 13 Apr 2000 00:18:52 -0500
Reply-To:     Jeff Taberski <jeff@TABERSKI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jeff Taberski <jeff@TABERSKI.COM>
Subject:      Re: BioDiesel
In-Reply-To:  <8c.279fb46.26269ee5@aol.com>
Content-type: text/plain; charset="US-ASCII"

At last! something I know a bit about!  I did my master's thesis at the
Univ. of Idaho on Biodiesel, so I could probably bore all of you with
tireless amounts of detail...but I'll try to summarize the just the engine
longevity related facts...and somehow relate this all to Vanagons.

First of all, "Cooking oil" and "Biodiesel" are not the same thing.  Cooking
oil (I'm assuming deep fryer oil) is most likely hydrogenated and will be
close to solid at room temperature (think Crisco!).  Biodiesel is modified
(transesterified) vegetable oil (not necessarily hydrogenated cooking oil).
Non-hydrogenated oils, such as canola oil and soybean oil can be used 100%
raw for a limited period of time before your engine is destroyed.  Biodiesel
is OK for long term use with some precautions.

As far as neat or raw vegetable oils go, they can probably be used in
pre-combustion chamber engines (pre-TDI VW engines) in no more than about
20% veg-oil/ 80% diesel blend.  Any more and you will have considerable
coking of the piston, ring sticking, and clogged injector nozzles in a short
period of time.  Actually, if you use any amount of unmodified raw oil in a
blend with diesel, you will likely see these problems anyway, but only after
a longer period of time.  Unmodified, non-hydrogenated vegetable oils also
are about 10 times more viscous than diesel fuel, so there are flow issues
to deal with.  Cooking oil (hydrogenated oils) don't flow very easily at all
at room temperatures and should not be used in the unmodified form.  I would
not use unmodified raw oils in any blend in a TDI.  Direct injection nozzles
seem to be extremely susceptible to coking and build-up when run with raw
oils.

Also note the energy content per unit volume is not as high with vegetable
oils compared to diesel, so you will take roughly a 10% hit on power on an
already underpowered Vanagon unless you tweak up the max fuel limit on the
pump...

Biodiesel is another story.  It's definitely kinder to the engine than raw
oil, but still has its problems.

Biodiesel, compared to raw vegetable oil, has the advantages of
1) much lower viscosity (closer to diesel),
2) less coking of the combustion chamber components
3) has a lower cloud and cold filter plugging point than raw oil, but not as
low as un-winterized diesel.

Disadvantages of Biodiesel compared to raw vegetable oil include:
1) it will dissolve any natural rubber component in the fuel system,
2) makes it more expensive since you now have to process the raw oil,
3) if you use Methanol, it is pretty dangerous to handle,
4) if you use Ethanol, it is pretty impossible to get (undenatured) in large
volumes without a BATF permit.

I am leaving out tons of stuff, but this is the meat most people on this
list would most likely be interested in.  I could go on and on about energy
policy, economics, emissions, dynamometer testing, advantages/disadvantages
of different types of vegetable oils, fuel processing, carbon balance in the
atmosphere, etc.

The American Society of Agricultural Engineers (www.asae.org) is the main
scientific/engineering body that publishes this stuff, although SAE has
some, too.  I'd take anything a consumer magazine says with a grain of salt.
The real detail is in the scientific publications.


Disclaimer:
The above is my opinion and does not represent the policy of my current or
former employer.  In other words, if you want something you can quote, quote
my published papers and not this email.  Paper references available on
request.

-Jeff

on 4/12/00 22:54, Tom Stone at TStone8359@AOL.COM wrote:

> The April/May edition of Home Power magazine has an article on running a
> diesel Vanagon on cooking oil.  I saw it a Barnes and Noble tonight.
>
> Tom
> '71, '78 and '85 Westys