From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Subject: Re: Grain Alcohol as Fuel
Date: Tue, 31 Oct 2000 16:22:38 GMT
>Is it possible to use grain alcohol or some byproduct as an efficient
>fuel for automobiles, planes, tec?
Yes. It was traditionally called "power alcohol" and it has been
used extensively in the past. However, like most alternative
fuels, it has limitations when compared to the pervasive
hydrocarbon-based fuels, modern terminology includes "fuel
The major problem being economics - fossil HC fuels are still
cheaper than many alternatives, even at US$30+/bbl. The US use
of fuel ethanol as a gasoline additive is achieved courtesy of
a mixture of federal and state subsidies that could total up
to 68c/US Gal.
>What is the name of the compound that would burn to do this?
>What is the chemical equation describing the reaction?
CH3CH2OH + 3O2 -> 2CO2 + 3H2O
Sadly, it doesn't go to completion in an IC engine, it
forms acetaldehyde and other nasties, necessitating the
use of an exhaust catalyst. Future alternatives could
include being used in fuel cells instead of IC engines.
>For those of you knowledgeable of the history of chemistry
>--when is the earliest point that an efficient grain-alcohol
>fuel could be produced?
Probably about the time man discovered fermentation, oh you
mean for IC engines, then around the turn of the 20th Century.
Then, as now, it was usually uneconomic if cheap HC-based
fuels were locally available. As the global crude-oil
markets developed, regional use of ethanol, either as a pure
fuel, or as an additive to Hc fuels, decreased. In the late
20th Century ethanol was used as one type of oxygenate
additive to gasoline to mitigate air pollution from older cars.
>If we CAN use grain alcohol as an efficient fuel, why don't we?
Economics - Brazil had a huge oil import bill, so decided to
use sugar cane-derived ethanol to reduce the import bill.
Sadly, for Brazil, some big companies made lots of money,
but the relatively-low technology ethanol vehicles created
lots of pollution ( no exhaust catalysts ), then the price
of crude oil collapsed, and the whole scheme made exports
with fuel cost components non-competitive internationally.
At one stage, they were looking at trying to export the
EtOH to the USA, where it would attract premium prices.
Naturally, the heavily-subsidised USA grain alcohol
producers were not amused.
>(Since it's a renewable resource, whereas crude oil is
Of course fossil fuels are renewable, they came from 100
million to 3 billion year old plant material and are part
of the larger, slower carbon cycle. It's just that some
humans are so impatient......
>Would grain alcohol be more or less pollutative than
Define pollution - certainly the acetaldehyde was a
problem in Brazil, but modern cars with good engine
management systems would be less polluting than
gasoline - if only tailpipe emissions are considered.
However, there are some other issues with alcohol
fuels, including distribution system costs if anhydrous
fuels are used - as anhydrous alcohol will readily mix
and disperse with water, and also absorb water from the air
with more water affecting starting if the engine is not
optimal - many of the technical issues have been overcome
in the Flexible-Fueled Vehicles trialled in the USA..
Global atmospheric carbonyl pollution has also been raised
as an issue in scientific journals if Ethanol was used in
engines at any significant fraction of fossil HC fuels.
In general, even with crude oil at $30+/bbl, ethanol
will not be conpetitive with gasoline without various
subsidies - which can also include punitive carbon taxes
on fossil fuels.
If you consider the various farm inputs, the fact that
ethanol has oxygen that doesn't contribute energy
( meaning that cars carry around more fuel ), and the
economic costs associated with subsidies ( wait for the
whines from ethanol proponents about the "hidden" military
Middle East subsidies - not withstanding any geopolitical
rationale ), and the water-miscible pollution ( MTBE is
less water misible, but isn't commonly naturally-occuring
- so there aren't bugs out there to consume MTBE, or to
blame for producing it - and, being virtually only man-made,
MTBE sticks out in potable water like a sore thumb ), then
ethanol isn't really a drop-in, low cost, replacement for
There is heaps of literature available on fuel and power
alcohol, including books devoted to the subject. A WWW
search should highlight sopme of the important aspects,
incuding the later technologies used in FFVs, but remember
that fossil fuels are pervasive because economic imperatives
drive large scale, global, fuel markets.