as these concerning the production of switchgrass, are needed.  However, the paper has several assumptions that are not verified.

1)      They use a third-hand reference source to claim that they can produce a net of 0.38 liter of ethanol from 1 kg of switchgrass .  No one in the world has been able to produce net ethanol energy from cellulosic biomass to date, except in paper models.  This is the reason that there is no commercial plant in the world converting cellulosic biomass into ethanol.  There are billions of dollars invested today in research to achieve this conversion and I support all this research.
2)        The authors never report that it takes from 2 to 5 times more cellulosic biomass than corn grain to produce 1 litter of ethanol.  Cellulosic biomass contains significantly less starches and sugars than corn grain.  One does not have to be a expert to appreciate this fact - all one has to do is hold a handful of switchgrass straw and a handful of corn to appreciate this fact.
3)     The authors imply on page 465 that our report on the conversion of switchgrass was based on "largely estimated values".  This is false. We used actual field data on the production of switchgrass based on data published by Dr. Roger Samson of McGill University who has been investigating switchgrass production for 10 to 15 years.  No one in world knows more about switchgrass production than Dr. Samson.  I was surprised not to see a single reference to his research investigations.
4)    Claims about reducing CO2 and global warming based on their data are obviously incorrect based on their claims of producing net ethanol energy from cellulosic biomass that has never been achieved on a commercial basis to date.  
5) The authors suggest that cellulosic ethanol sources can provide 30% of U.S. current petroleum consumption. The report advocates using 1.3 billion tons of cellulosic biomass.  They are suggesting using nearly 66% of all forests, all agricultural crops, and all grasses each year to produce this cellulosic ethanol.  Literally the U.S. would be stripped of its vegetation.  The result would be that soil erosion would intensify, water runoff would increase, and global warming would increase.
6)    I am truly concerned when people publish some unscientific opinions such as these because they mislead the people and politicians.   At present there is no easy solution and we in science need to be investigating all potential renewable energy technologies and cease claims that ethanol from cellulosic biomass is the solution to all U.S. energy problems.  A truly thorough examination of biomass and its environmental relationship to water, land, and solar energy is needed.

today and in the future. During the next decade, companies across the U.S. will build biofuel processing plants that use agricultural residues, municipal and forestry wastes, and a host of new energy crops. Swithgrass is one example of the opportunity for biofuel feedstock diversity. Switchgrass is an ideal energy crop for many areas of the country. Recent research in Nebraska and other locations confirms that we can expect a positive trend in efficient production of energy crops that can help meet the nation's transportation needs. Switchgrass and other energy crops will continue to generate a host of positive economic and environmental benefits experienced in ethanol producing states during the past decade.