OFF TOPIC: Re: America needs therapy

[Eugene Leitl]

This is about as off-topic as the mold issue. You've been warned.

On Mon, 1 Oct 2001, Harmon Seaver wrote:

> > Biodiesel and bioethanol are horribly inefficient as far as conversion of
> > solar energy and agricultural area is concerned. Large scale agriculture
> > is not exactly environmentally neutral. They're extreme niche or gimmick
> > fuels at best.
>
> Where do you get that from? Are you saying that farmers aren't growing
> canola oil at a profit? Farmers are also growing corn and that corn is
> turned into ethanol at a profit.

No. I'm saying if you use bioethanol, biodiesel or oil made from
agricultural products you're milking a negligable fraction of the solar
constant (1.4 kW/m^2 flux hereabouts), even solar constant at the bottom
of this gravity well (varies greatly). Plus, you kill soil, reduce
biodiversity, contaminate ground water, reduce ground water level plus
cause salination in susceptible areas, burn energy for machines,
fertilizer & Co and create waste. There are also less tangible but
nevertheless real factors such as high material fluxes, associated
pollution, perpetuation of Carnot cycle machines and agromafia.

What we need is sufficient control of molecular self-replication that we
can use photons directly for photosynthesis or water photolysis. Before
we'll get that, we'll have to settle for conventional thin-film and
polymer photovoltaics, electrolysis and photoelectrolysis/photosynthesis.
I would think that CuInSe thin film would do very nicely today if
facade-integrated, before we get polymer.

> http://journeytoforever.org/ethanol.html
>
> > Ethanol is a highly efficient fuel. A study by

Energy density of ethanol is about half of gasoline. You *can* use it in a
fuel cell or a fuel reformer, but methanol is easier. Methanol <->
synthesis gas conversion is really clean.

> >                                   the Institute of Local Self-Reliance in the
> >                                   US found that using the best farming and
> >                                   production methods, "the amount of energy
> >                                   contained in a gallon of ethanol is more than
> >                                   twice the energy used to grow the corn and
> >                                   convert it to ethanol".

So, assuming these people haven't been pulling data straight from their
ass, you have to burn half of the ethanol you would get from a square
meter of a field in order to do it. Not counting the presence of said
field, the agricultural infrastructure and the agrohol plant.

> >                                   The US Department of Agriculture says
> >                                   each BTU (British Thermal Unit, an energy
> >                                   measure) used to produce a BTU of
> >                                   gasoline could be used to produce 8 BTUs
> >                                   of ethanol.

Now this says something else than journeyforever folks said. 8:1 is
something else than 2:1.

> >                                   The non-profit American Coalition for
> >                                   Ethanol says ethanol production is
> >                                   "extremely energy efficient", with a positive

Energy efficient as compared to what exactly? Nuke, fossil, photovoltaics,
wind? And, of course, energy is only a very small part of the picture.

> >                                   energy balance of 125%, compared to 85%
> >                                   for gasoline, making ethanol production "by
> >                                   far the most efficient method of producing
> >                                   liquid transportation fuels".

Now, it's only 125%. Very strange numbers, these.

> >
>
>       If you are refering to the paper done by Pimental, that study was
> seriously flawed (so much so that one might think it was paid for by big oil)
> and thoroughly debunked.  See:
> http://journeytoforever.org/ethanol_energy.html

I do not refer to the study of Pimenthal, just seat of the pants ecology
and 8th class highschool level physics. I don't have time to google for
this stuff, but I'm sure you'll find enough references as to why
bioethanol and biodiesel are hardly a silver bullet.

-- Eugen* Leitl <a href="http://www.lrz.de/~ui22204/">leitl</a>
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