Date: Thu, 19 May 2005 09:44:05 -0700
Reply-To: Alan Sinclair <alan@DETERMINISTICNETWORKS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Alan Sinclair <alan@DETERMINISTICNETWORKS.COM>
Organization: Deterministic Networks Inc
Subject: Re: oil and gas
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Here's my final rant on this with some of the figures from my college energy class. Apologies that
it's just abbreviated notes -- I'm pushed for time (haven't looked up refs, follow up offlist if you
want). Hope it gives a better view of the fuel-from-crops issue. Basically, alcohol is a better
energy product to aim for than diesel ... maybe I should begin on our Westie.
The negative energy balance figures originated in a study by David Pimental, but he was on Mobil's
payroll at the time. USDA did a more exhaustive study and got ~2:1 positive energy balance for
corn. This left out the CO2 and its industrial uses, and the other byproducts.
Dr Diesel originally specified use of palm oil in his engines.
Oil is not so productive a crop as alcohol.
canola ~ 50 gallons/acre
palm oil 500 g/a
Alcohol from crops is better, though corn sucks as an alcohol energy crop
corn ~ 250 gallons/acre of alcohol
cane, manioc, beet give 1200-1800 g/a
cattails ~ 2500 g/a (from the starchy roots)
in S. California experimental rotating cropping of beet 6 months with cane 6 months gave 4000 g/a
DOE says 50% of US fuel possible from corn, so a shift to other crops would give us 150% or more of
our fuel needs
The first internal combustion engines used alcohol. Before 1917 gasoline was unknown outside cities
and farmers made their own alcohol fuel
Rockefeller managed the politics (with a $4 million input, equivalent to $400 million now) to force
switching away from alcohol to petro-diesel
US corn production (2002 figures):
1% becomes human food (as corn)
2% high-fructose corn syrup
7% alcohol fuel
70% cattle feed
(20% goes abroad)
Current production of corn is 2x what's needed to feed the global population.
Cattle are originally forest browsers -- their four stomachs are for cellulose digestion. Starch is
an inefficient food for cattle.
Dried Distillers Grain Seeds (DDGS) is the byproduct of alcohol production. The is mostly cellulose
and is a much better cattle feed than corn. 35lbs of DDGS replaces 100lbs of corn feed, giving 17%
more meat 13% faster.
Cattle convert 10lbs of feed to 1lb of meat
Fish convert 2 lbs feed to 1lb meat
ADM trial plant:
100,000 gal alcohol output
the DDGS goes to fish farm growing Tilapia
the CO2 is fed to greenhouse @ 1200 ppm giving 19 times the usual yield per sq foot
(5000 head lettuce per day, from 5 acres of greenhouse, grown from seed in 35 days)
(love ADM or like me loathe 'em, this is a neat trick)
Alcohol as fuel:
alcohol has better flammabiity range than gasoline (alc ~9:1, gas: ~14.7:1)
alcohol is 106 octane so slower combustion, so can have earlier spark, so more efficient
(gas ~25% efficient, alc ~45% efficient)
you lose about 10% mpg with alcohol on simple engine conversion.
high-compression conversion with right jet, timing etc alcohol gives ~10% better mpg plus ~40% more
horsepower.
NOx byproducts are lower with alcohol because of the reduced combustion temp
All US auto manufacturers make at least one dual gas/aolcohol model (to get a tax credit), using a
Flexible Fuel Unit (FFU) A sensor on the fuel line detects the percentage of alcohol.
You can do-it-yourself distillation of up to 10,000 gal/year of alcohol with simple permit from the
feds -- use windfall fruit, or old doughnuts (those are better for biodiesel iirc) or whatever is
locally available