I heard that the limit on biofuels is that they would require devoting the
entirety of our agricultural surfaces to the corresponding cultivations if
we wanted to run all our vehicles on them. Otherwise their net CO2 emission
is zero without a doubt, as all they can release to the atmosphere is what
they have taken from it a year or so before for their photosynthesis, unlike
fossil fuels which did so a very long time ago.
Michel
----- Original Message -----
From: "Philip Winestone" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, March 09, 2006 11:39 PM
Subject: Re: Farrell responds to Pimentel regarding ethanol
Most of the studies I'm aware of discuss the manufacture of ethanol from
corn. I know first-hand of an interesting process that uses cellulose as
its feedstock. The reaction is via an enzyme that initially converts the
cellulose to sugar... then the normal fermentation process to ethanol.
The process lends itself very nicely to waste wood: bark, chips, sawdust,
stumpage... and could easily be implemented by the pulp and paper industry
which has the logistics in place to undertake such projects. And this
industry is having its problems right now, especially here in Canada.
All it takes is some investment.
Many energy expenditures occur, even/especially with oil-based fuels.
Imagine how much energy it takes to transport fuel from the the wells to
the refineries dotted about North America to the fuel depots and then to
the individual retail outlets. The conversion process from raw oil to
different fuel types also takes a substantial amount of energy.
Same problems with ethanol: manufacture and distribution. I haven't read
the various studies on the subject so I don't know what parameters were
used. I can only say that some time ago similar studies were done to
compare solar energy (energy to manufacture the panels, etc.) and these
were all deeply flawed - either accidentally or deliberately.
Philip.
At 04:19 PM 3/9/2006 -0500, you wrote:
See:
http://rael.berkeley.edu/EBAMM/ERG-NPR-letter-1-30-06.pdf
Farrell agrees with Pimentel that ethanol takes a lot of input energy --
although he does not specify how much in this letter. He says that
Pimentel was wrong and that the Berkeley study did take into account the
energy used by farm machinery.
His main point is that much of the input energy for ethanol production
comes from fuels other than oil, so it produces a net increase in
transportation fuel. Maybe so, but I doubt it is economically viable, I
doubt it does anything to reduce CO2 emissions, and I expect that if the
subsidies were withdrawn no one would buy the stuff.
- Jed
