Greetings,
What are the best crops for biofuels?
Oil palms are some of the best, along with coconuts. Actually, some
algae have the potential of being orders of magnitude better and growing
in a far more compact environment. Here is a partial list for your
amusement.
http://www.journeytoforever.org/biodiesel_yield.html
How do corn/maize/soy stack up against each other?
As you'll find on the above list, none of these are particularly
promising. However, don't make the mistake of thinking that all biomass
has to be grown as a crop for fuel. There are many waste products which
can be turned into biomass fuels. Bagasse from sugar cane, trester from
wine production, weeds and leaves and lawn clippings, can all be turned
into useful biofuels either as ethanol or through other exotic
processes. Whey from cheese and spoiled crops and various waste streams
from food packaging plants can be converted into fuels. Animal and
human fecal matter can be converted, through supercritical water
processing, into liquid fuels with reasonably high energy content. Many
of these fuels can also be pyrolyzed or methanized in digesters to
produce compressible gases.
Is there a perennial version of these plants?
There are a huge variety of plants that could could be used for biomass
to be sure. It really depends upon the environment as to which will be
used in a particular place, but there are appropriate biomass crops for
just about any setting.
How dependent are they on fertilizer?
Many can grow in quite marginal areas. Switch grass can be grown in
marginal areas and has the advantage of stabilizing the soil against
erosion. Creosote and mesquite bushes grow in very rough and otherwise
unproductive areas and have also been proposed as candidate biomass fuel
crops. Clearly things like tumbleweeds plant themselves and tend to
grow without the need for human intervention. However, certain biomass
streams, after fuel has been extracted from them, leave residues which
still contain useful fertilizers. So fertilizers can be obtained
without fossil fuel inputs.
Can they grow sustainably by rotation?
Yes. Plants have been here substantially longer than man. There are
many sustainable things that we can do.
--
Quibbler (quibbler247atyahoo.com)
"It is fashionable to wax apocalyptic about the
threat to humanity posed by the AIDS virus, 'mad cow'
disease, and many others, but I think a case can be
made that faith is one of the world's great evils,
comparable to the smallpox virus but harder to
eradicate." -- Richard Dawkins
