This 'report' (from a site that will be red rag to a bull to some list 
members) argues that biofuels are at best nowhere near as clean and 
green as they appear, and at worst are worse than not developing them 
at all.

        http://ww4report.com:80/node/2864

Issues include, actual net energy gains (or not), CO2 net releases, 
affects on rain forest, food crop displacement, net pollution and 
more.

Some reputable sources that also add food for thought include:

University of Minnesota
"Environmental, economic, and energetic costs and benefits of 
biodiesel and ethanol biofuels
Jason Hill, Erik Nelson, David Tilman, Stephen Polasky, and Douglas 
Tiffany

        http://www.precaution.org/lib/biodiesel_vs_ethanol.060725.pdf

________

Cornell University
Ethanol Production Using Corn, Switchgrass, and Wood;
Biodiesel Production Using Soybean and Sunflower
David Pimentel1,3 and Tad W. Patzek2

    http://www.precaution.org/lib/ethanol_and_biodiesel.050301.pdf

>From the above, the following conclusions are worth noting:

CONCLUSION

Several physical and chemical factors limit the
production of liquid fuels such as ethanol and
biodiesel using plant biomass materials.
These include the following:

(1) An extremely low fraction of the sunlight
reaching America is captured by plants. On
average the sunlight captured by plants is
only about 01.%, with corn providing 0.25%.
These low values are in contrast to photovoltaics
that capture from 10% or more sunlight,
or approximately 100-fold more sunlight
than plant biomass. [Russell - *]

(2) In ethanol production the carbohydrates
are converted into ethanol by microbes,
that on average bring the concentration of
ethanol to 8% in the broth with 92% water.
Large amounts of fossil energy are required
to remove the 8% ethanol from the 92%
water.

(3) For biodiesel production, there are two problems:
the relatively low yields of oil crops
ranging from 1,500 kg/ha for sunflower to
about 2,700 kg/ha for soybeans; sunflower
averages 25.5% oil, whereas soybeans average
18% oil. In addition, the oil extraction
processes for all oil crops is highly energy
intensive as reported in this manuscript.
Therefore, these crops are poor producers of
biomass energy.


________

Russell says:

* - type setting suspect.
Appears to mean 0.1% average and 10% for photovoltaics.
Corn at 0.25% is 40 times worse than PV.


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