Obama's biofuel challenge

Intressant om utmaningarna för sk 2nd generation etanol. Utmaningarna med 1st generation känner vi ju alla väl till vid det laget.

"As early as 2013, EISA envisages 1 billion gallons of ethanol will come from second-generation ethanol produced from cellulose, rising to as much as 16 billion gallons by 2022.

There is only one problem: the United States is not producing any second-generation non-corn ethanol in significant quantities at the moment. So a whole new industry will have to be brought into existence within less than four years and become one of the largest industries in the United States within the next 10 years.

Necessity is the mother of invention. But developing a major new industry based around cellulosic feedstocks able to operate on a semi-commercial basis in such a short period presents a huge technical and scientific challenge.

Work on second-generation ethanol has been under way for more than 20 years. But the biochemistry of producing ethanol from cellulosic feedstocks is more complex, and therefore expensive, than producing ethanol from corn starch.

Producing ethanol from corn starch essentially uses the same brewing and distilling techniques honed over the last 5,000 years for the production of beer and spirits.

Producing ethanol from agricultural waste, specialist crops and other sources of cellulose requires much more complex pre-processing. Pre-treatment is needed to break up the cellulose structures; separate the cellulose from the associated hemicellulose and lignin; convert the cellulose and hemicellulose into alcohols using separate enzymes for each; all the while handling the lignin which would otherwise retard the distillation process.

Processing techniques require large quantities of steam, acid, or both, and more specialist enzymes than typical in the brewing industry.

At a time when even corn-based ethanol is struggling to compete with fossil fuel gasoline at oil prices of less than $70 per barrel, the complex cost structure of the cellulosic ethanol industry is hopelessly uneconomic."

http://www.guardian.co.uk/business/feedarticle/8200318