energy crops, follow up

Toby Bradshaw toby at milton.u.washington.edu
Mon Aug 24 10:04:35 EST 1992


In article <dangold1.714665660 at pv1414.vincent.iastate.edu> dangold1 at iastate.edu (Daniel M Goldman) writes:
>Follow up to Tony Travis:
>  I'm no biochemist, but if you want to store energy, my memory
>tells me you want to use lipids.

Well, I am a biochemist, and if energy _density_ is the criterion then
lipids are a good choice.

>After all, the petrol we are
>trying to replace is a hydrocarbon.  Plants tend to use lipids
>to store energy in seeds-e.g. canola oil, has been discussed.

Here's the rub -- the stored lipids are a very small part of the
plant's biomass, and to use that oil as fuel much more carbon must
be fixed by the plant than if the biomass is used more or less
directly.  This means more hectares of oilseed crops must be
planted to produce the same amount of fuel as a biomass crop
produces (ignoring the residual value of the seed meal, an
obvious flaw in my argument).

>I still believe the issue is that we need:
>     1) A crop, complete with genetics and a production system.
>     2) An extraction and processing/refinement system.
>     3) Perhaps a new or altered engine to replace the gas engine 
>        we now use which was originally designed around gasoline.

No argument there, except under 2) I might include conversion
of biomass to liquid fuel or its moral equivalent (electricity
for electric vehicles).  I would also add that costs, both immediate
(fertilizer, fuel for planting and harvesting, any pesticides
or herbicides that are required) and long-term
(soil erosion, pesticide/herbicide residues, wildlife habitat,
other ecological concerns) costs must be made part of the
equation.

>Research tend to focus on pieces of the puzzel, but perhaps more needs
>to be done on integrating the system.

Call your congresscritter  :)

>Whether we should focus on sugars
>lipids or something else

Cellulose leaps to mind.

>is a good question, and would be a useful thing
>for plant breeders to know.

We tree breeders already know  :)

>  My argument is for doing at least as much work on integrating the 
>components of the system as the components themselves.  Biologists,
>engineers and people in energy physics need to educate each other and
>discourse a lot more! -DmG

It happens, but not usually on a scale sufficient to provoke
a paradigm shift in the scientific or general populations.  There's
always the carbon tax...

Toby Bradshaw
Biochemistry and Forest Resources
University of Washington



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