permaculture

[Adam Donnison <adam@saki.com.au>]

There are technical issues here which probably need to be cleared
up.  Firstly, a diesel engine will run on pure vegetable oil, if
the oil is heated and the engine started on a more traditional fuel.
Indeed the inventor of the diesel engine initially intended it to
be run on vegetable oil.

Biodiesel is a product of methanol, caustic soda and oil or fat.
In its liquid form it is several orders of magnitude less toxic than
diesel, but once burnt has similar pollution characteristics of its
mineral cousin.  It is worse in some emissions, and better in others,
but all in all it is pretty close.

A diesel engine will not run unmodified on gas.  Unlike the petrol
engine, the engine characteristics are just not appropriate.  The
diesel engine works on a "compression-ignition" mechanism where the
high compression causes the air-fuel mixture to heat to its ignition
point. Running on high-octane fuel or on a gaseous mixture is likely 
to cause detonation, rather than a controlled burn, resulting in the
engine self-destructing.

Hydrogen and biodiesel are just stopgap measures.  As an example,
even if all of the world's oilseed production were immediately switched
to biodiesel production it would not meet the current needs of the
world's diesel fleet.  Another example - all of the hydrogen is
currently produced by cracking natural gas (methane), so it is yet
another fossil fuel. What is needed is a realisation that the
technological "quick fix" is no longer a solution and we need to
radically rethink our use of energy.

Sure, lets investigate the use of renewable "drop-in" replacements
for fossil fuels, but let's not use it as an excuse to sit back
and assume the world's energy use can continue to rise.  Any system
that assumes that energy consumption can continue to rise dooms
itself to "heat-death".  One way or another we need to come to grips
with this. 

I'm sorry if this sounds gloomy, but my belief is that we are all
part of the problem. By giving the internal combustion engine a
longer lifespan we are just contributing to our own demise.  We must
work towards a better future, one that doesn't rely on burning our
fossil inheritance and leaving the world a basket case.  Hydrogen,
biogas, biodiesel are all side issues. They simply prop up the
current energy economy and give no real plan for how we manage the
dichotomy between growing energy consumption and dwindling fossil
reserves.

Adam
Luomuvegaaniverkosto wrote:
> Thanks for the interesting info on hydrogen.
>
> There's a lot to focus on, but since it seems that natural biogas is used
> as a source for hydrogen production and methane has a role in
> transportation of hydrogen through the pipelines, it is good to also have
> an eye on german research on biogas production potential through
> fermentation of white clover, which states an amount corresponding to
> 3300-4700 liters of diesel fuel from one hectare in a year:
>
> Stinner, Walter; Möller, Dr. Kurt and Leithold, Prof. Dr. Günter (2005)
> Biogaserzeugung im viehlosen Betrieb: Effekte auf Stickstoffmanagement,
> Erträge und Qualität  [Biogas production in a stockless farming system:
> Effects on nitrogen management, yield and quality].
>
> Möller, Dr. Kurt; Stinner, Walter; Deuker, Arno and Leithold, Prof. Dr.
> Günter (2005) Biogaserzeugungspotential aus Gülle und Koppelprodukten in
> viehhaltenden und viehlosen Betriebssystemen des ökologischen Landbaus
> [Potential of biogas production by using slurry and coupled products in
> organic farming systems with and without animal husbandry].
>
> both can be found from Organic Eprints database at http://orgprints.org :
>
> Diesel engines can propably use biogas as a fuel, (maybe with 10 % of
> biodiesel), so that can be used in production of electricity and heat
> (usefull at least in north). In transportation, I don't know how much
> there is difference in between production of tanks for compressed biogas
> and tanks for compressed hydrogen. Anyway, I wouldn't either hype
> biodiesel as a solution for overconsumption of energy and unnecessary
> transportation, but it can be used without any changes in the existing
> diesel engine or fuel tank, without producing new engines with or without
> more advanced technology. So biodiesel can be used as long as diesel
> engines do exist in the world and we can still research the hydrogen even
> though that wouldn't be available for everyone in the near future, even if
> mass produced.
>
> Orava Ituparta


--
Adam Donnison                                  email: adam@saki.com.au
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