[Diy_efi] Is E85 worth it?

[Klaus Allmendinger]

Hi,

I saw a documentary a while back about a test the US army did:
Fire on 3 cars with incendiary rounds. About 20 rounds/car in the trunk
area.

1st car with a regular gasoline tank in the trunk
2nd car with a propane tank in the trunk
3rd car with a hydrogen tank in the trunk

First and Second car immediately caught fire and burned out, the
gasoline car did so spectacularly.
Third car had some "patchable" holes, but the hydrogen vented through
the holes and burned above the car, not even damaging its paint. Filmed
using a infrared camera so the H2 flame was visible. Even setting the
venting hydrogen on fire proved to be difficult and was only possible by
firing the rounds through the venting hydrogen, not into the car.

Hydrogen can burn in extremely diluted mixtures with air, that's true.
But the explosion danger is almost non-existant at these extreme
dilutions because the flame-front speed becomes extremely slow (but is
much faster than gasoline when using near stoichiometric mixtures).
Also, because H2 is so light, it will dissipate almost immediately from
normal, not hermetically sealed places like a car interior.
IC engines running on hydrogen may have no throttle because of the
extreme dilution tolerance of hydrogen. They can be throttled, like a
diesel, purely by mixture control. Thermodynamic efficiency is very
high, higher than a diesel, but lower than a fuel-cell system.
At low loads the mixture is so weak, and therefore the flame-front so
slow, that spark ignition has to happen even before the intake valve
closes. This of course is difficult because of the danger of backfiring
into the intake.
On a per pound basis Hydrogen has the most energy of any IC fuel. Of
course by volume it's a different matter as H2 has such a low density.

As to hydrogen production:
There has been an article in the (I think) June SciAm about a new
discovery using Titanium Oxide nanotubes. If exposed to air and
sunlight, they break up Water into H2 and O2. Even though the process is
not yet very efficient, according to the article, the surface area of a
typical residential roof would yield the energy equivalent of 10 Liters
of gasoline in H2 per day. The efficiency is expected to double within
the next few years. Production cost of the nanotubes is expected to be a
tiny fraction of solar cells.

As promised, here also some studies about energy efficiency of corn
based ethanol:
http://www.ethanol.org/documents/NetEnergyBalanceofEthanol.pdf
http://www.ethanol-gec.org/corn_eth.htm
http://www.ers.usda.gov/publications/aer721/AER721.PDF

Regards,
Klaus






-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]
On Behalf Of Steve Ravet
Sent: Thursday, September 07, 2006 7:14 AM
To: diy_efi at diy-efi.org
Subject: RE: [Diy_efi] Is E85 worth it?

 

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Ian Molton
> Sent: Thursday, September 07, 2006 5:22 AM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] Is E85 worth it?
> 
> Mike wrote:
> > At 02:11 PM 9/7/06, you wrote:
> 
> > Anyone know the current practice for dealing with an H2 fire ?
> 
> AFAIK, run like hell :)

Seen on the back of a T-shirt:

"I am a bomb technician.  If you see me running, try to keep up"

--steve



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