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These are great questions. Perhaps we should try to work through 
these as a group in more detail during the spring semester. Here's 
my two cents:

I think it is probably fair to conclude that familiar industrial 
agriculture crops are not a sustainable alternative energy answer 
for many of the reasons you suggest. Plants that are naturally 
productive and do not require such intensive irrigation and 
fertilizer inputs (most of these plants are often thought of as 
"weeds") would clearly seem to be a more promising alternative. 
Also, as a recent posting suggested, technological and/or 
regulatory advances that significantly ratchet down consumption of 
fuels (i.e., greatly improved fuel mileage for cars) are an 
absolute necessity if we're serious about reducing greenhouse gas 
emissions or just about anything else having to do with 
sustainability.

I think one issue you raise that I can address in some detail is 
the carbon effect associated with the utilization of bio-waste 
material. While it is true that CO2 is released through 
combustion, the carbon released through this process was, in 
principle, fixed in recent times through biological activity. 
Thus, no "new" carbon is being introduced into the atmosphere 
through this process - in essence, carbon that is already part of 
the global cycle is being recycled. Of course, carbon is not being 
permananently sequestered out of the global cycle through this 
process, either.  Therefore, bio-waste utilization is often 
referred to as a "carbon neutral" process.

By contrast, the burning of fossil fuels literally introduces new 
"fossil" carbon into the atmosphere. The advantage of bio-waste 
utilization over fossil fuels in terms of greenhouse gas emissions 
fundamentally boils down to the idea that it is a carbon neutral 
process, as opposed to a carbon loading process. The advantages 
are even higher when dealing with human and/or animal wastes, 
principally because large amounts of fossil fuels are often used 
in traditional wastewater treatment. Utilization of these wastes 
not only produces carbon neutral energy, but also eliminates most 
of the fossil fuel energy used for wastewater treatment. In 
addition, efficient recycling of nutrients such as nitrogen and 
phosphorus contained in these wastes has further greenhouse gas 
benefits because less fossil energy has to be expended for 
production of fertilizers.

Hope this is at least somewhat helpful. Happy holidays to 
everyone!

Jason

--
Jason Evans
Ph.D. Candidate, Interdisciplinary Ecology
School of Natural Resources and the Environment
University of Florida
(352) 466-4549 - home office
(352) 328-1199 - cell

BioEnergy and Sustainable Technology Society
http://grove.ufl.edu/~bests/



On Thu Dec 21 01:18:47 EST 2006, "MARTIN,ELIZABETH J" 
<[log in to unmask]> wrote:

> To anyone willing to address my question:
> 
> I was wondering if someone would mind directing me to some 
> information regarding the pros and cons of biofuel vs. petroleum 
> in terms of land use and water consumption.
> 
> While I fully agree that there is a dire need to reduce reliance 
> on petroleum and other non-renewable resources, I am concerned as 
> to how it balances out on the other end of the spectrum.  
> Currently over 1 billion people do not have access to safe 
> drinking water, resulting in millions deaths every year due to 
> unsafe and unsanitary water conditions.  The main problem is the 
> agricultural techniques used to produce crops such as corn, 
> wheat, soybeans, etc.  The largest problem is the net loss of 
> water and the destruction of land due to irrigation.  From what 
> I?ve been reading, it appears that the main alternatives to 
> petroleum lie in the use of these organic materials as potential 
> fuels.  So my main point is this, even if biofuels replace 
> petroleum and reduce green house gases and air pollution, won?t 
> the result be an even bigger problem due to water scarcity?  I 
> understand that no one can know if this will even be a problem, 
> but I can?t help but wondering if biofuels are the answer, or if 
> they are a catch 22.
> 
> I also have a slight problem with the burning of natural and 
> human wastes.  While this does eliminate the growing problem of 
> landfills and the release of methane gas into the atmosphere, 
> isn?t it still slightly retroactive because combustion of any 
> material releases carbon dioxide?
> 
> I'm terribly sorry if these questions seem ridiculous or 
> completely off base, but I'm having trouble finding answers.
> 
> Incase anyone was wondering where I got my information on water 
> scarcity:
> www.blueplanetproject.net
> 
> There is also a very informative article available at:
> http://www.qmw.ac.uk/~ugte133/courses/environs/cuttings/water/
> Click running.pdf
> 
> Thanks.
> Liz
> --
> MARTIN,ELIZABETH J
> 
>