So fuel tax is too high? We should campaign to see big reductions in
this tax? How long do we think fuel will last us anyway?
At the time of the last fuel crisis, someone suggested to me that we
could run vehicles on a limitless supply of ethanol, and we need not
worry about the fact that fuel production is already almost at its peak,
and ready to start tailing off.
This kind of argument fails to consider just how much fuel we
are all using. Here is an excerpt to my answer to that writer.
>again, Brazil has been doing this
[producing ethanol for motor vehicles]
>quite successfully for many years
Successful in what sense? despite the ideal conditions for ethanol
production, government subsidy is still required to make ethanol
production cost effective.
Because ethanol has a calorific value about half that of petrol, it is
necessary to mix the ethanol with petrol in order to avoid the need for
huge fuel tanks. Currently I understand that Brazilian fuel is between
22% and 24% ethanol.
Various vehicles do run on pure ethanol, but these are generally
vehicles such as city taxis, where the shorter range is less of a
In Brazil the sugar cane region is known as the Zona da Mata - a huge
swathe of land that has all but replaced the Mata Atlantica tropical
forest. To grow sufficient sugar to run all those vehicles, the forest
has been destroyed.
In any case, ethanol in Brazil is produced from sugar cane. I believe
that Eucalyptus is often used as biomass.
To give some idea of the amount of sugar cane alone that is required to
produce ethanol, consider these figures:
It is estimated that the net energy yield of ethanol produced from sugar
is 30GJ/ha each year. Diesel fuel has a calorific value of about 35 KJ/L
at 15 degrees Celsius, so assuming this is 10% more than petrol, we find
that the net yield of energy is equivalent to approximately 1000
litres of petrol equivalent per hectare per year.
Now I know that the average petrol station distributes about 2 million
litres of fuel per year, so we require about 2,000 hectares of land
(capable of growing sugar) for each petrol station. (I am not sure what
total UK usage of petrol/diesel is, but would be interested in using
those figures in this context, if anyone has them).
At current levels of usage (which are growing all the time), we don't
have a hope of servicing our needs through ethanol production.
Brazil manages it because they have a climate in which they can grow
sugar cane, and huge tracts of forest that they can cut down to place
the sugar plantations. Even so, they still rely heavily on
petrochemicals to balance their fuel budget.
In theory alcohols are sustainable fuels, but in practice we do not have
the land area to grow sufficient quantities for our needs.
What can we do? Are we all doomed? or is there really a sensible way
to reduce fuel consumption in a way that will not destroy our economies.
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Also, take a look at the fuel