[SGVLUG] Because we have talked about this before.

[David Lawyer]

On Fri, Jan 11, 2008 at 05:29:43PM -0800, matti wrote:
> 
> --- Michael Proctor-Smith <mproctor13 at gmail.com> wrote:
> 
> > Ok, from slashdot.
> > 
> > http://hardware.slashdot.org/article.pl?sid=08/01/11/1847256
> > 
> > USDA and farmers took part in a 5-year study of switchgrass, a grass
> > native to North America. The study found that switchgrass ethanol can
> > deliver around 540 percent of the energy used to produce it, as
> > opposed to corn ethanol which can only yield around 24 percent. 
> 
> Holy Cr#p!
> 
> so we blow 4 units of energy to produce 1 unit?

No.  This statement is not what the Scientific Am. article said.
Slashdot got it wrong.  It said 124% but that's also wrong.  

Pimentel says both ethanol and switch grass are losers (it takes more
energy to make them than you get from them).  But I believe they are
even worse losers than he thinks since he underestimates the energy
cost of human labor required.  See my article on the energy cost of
human labor http://www.lafn.org/~dave/energy/human_energy.html "Human
Energy Accounting".  A lot of studies of ethanol don't even account
for human energy in any way.  But a correct accounting for it is to
multiple the food calories expended by an ethanol worker at work by
roughly 1000.  See my article for why, it's not easy to explain.

It's often stated that for every calorie of food we eat it takes about
10 calories of fossil fuel to produce it.  With this kind of a
penalty, how can we expect to use food as a fuel?  Instead of a 10:1
ratio, I estimate about 15 in my article, based on studies by others.

Well, if we grew food without fertilizers and machinery, using just
human and animal labor, it might be feasible to not contribute to
global warming by doing this.  One problem.  The crop yields per acre
would be only such as to supply about 1/3 of the population with food,
not to mention any fuel for transportation, etc.  If you really want a
sustainable population, we might consider the population of native
americans at the time Columbus rediscovered America: perhaps 10
million "Indians" in the US.  Were the native american civilizations
of low enough population to be sustainable?  Maybe not since some of
them collapsed like the Mayan civilization.

For every calorie a person in the US eats, about 100 calories are
used to support that persons life: fertilizers, farm machinery,
housing, transportation, etc.  But that doesn't count the service
worker energy where service workers transfer some of their embodied
energy to the people they serve.  So the food energy from agriculture
just dwarfs the energy we use from fossil fuels.  Ares in his 1952
book on "Energy Sources" thought biofuels not feasible.  On p. 243 he
states: "Those who know the most about vegetation are inclined to
believe that the best that technology will be able to do in the
decades ahead will be to provide a sufficient amount of food for the 2
1/3 billion people of the earth."  Well, were now at well over 6
billion people and over a billion of those are malnourished.  Are we
going to reduce food production to produce biofuels that likely don't
even save any energy due to the fossil-fuel inputs required?

Fuels from grass sounds deceptively enticing.  To be sustainable, you
have to replace the nutrients that you remove from the soil when you
harvest the crop including minerals and humus.  If you don't have
humus, the minerals in the soil leach out by water to the subsoil where
plants can't use them.  If you use all the plant and have no
protective cover for the soil, then you get erosion and loss of
topsoil, which is already a serious problem.  So one way to preserve
the soil is to mow the grass, but return all the mowed grass to the
soil so as to provide minerals and humus to the soil.  Better yet,
don't bother mowing it and just let it die out each year to provide
nutrients for the next batch.  Soil doesn't have any was of generating
minerals (except for nitrogen which nitrogen-fixing bacteria can
capture from the air) except over geologic time.  For example,
volcanic ash may help fertilize the soil and ash fallout from forest
fires helps redistribute minerals.

Then there's the problem of water needed for agriculture.  Falling
water tables (there's even been a big drop in Pasadena), etc.

Another question: Where is all this surplus grass?  Haven't grasslands
been converted to farms, or isn't it being used for grazing of
domestic animals and wildlife?   Are we going to plant grass on farms
where we are now growing food?

So the government is now wasting many billions of dollars subsidizing
biofuels which are likely making global warming worse rather than
better.  And almost no unbiased and knowledgeable people are looking
into the problem.  It's just too complex, controversial and
multidisciplinary, but it's terribly important.

			David Lawyer