"mandates 36 billion gallons by 2022, with 21 billion gallons coming from so-called cellulosic ethanol."

They could simply legislate the end of the 2nd law of thermodynamics and be done with that...

The 21 billion gallons from cellulosic ethanol will never happen for several reasons. As pointed out the first is that the technology to commercially manufacture it does not exist. When farmers started making ethanol big time from corn in the 1980's, the technology was centuries old. Secondly the market for the raw cellulose in what ever form contemplated does not exist. The market for corn did exist with all the benefits of hedging and usefulness in financial planning. Thirdly cellulosic raw material are very bulky by nature, making storage problematic. Corn is stored in bins that have been constructed over the last 50 or more years. There are still problems at harvest in finding storage now. Raw materials for ethanol plants can not simply be left outside because bacteria start to decay the product. This interferes with the bacteria used to make the ethanol causing major problems in the plant. Even in Brazil, if I'm not mistaken, the sugar used for ethanol is stored indoors after being extracted from the cane. Fourthly cellulosic raw materials will be highly labor and energy intensive due to undeveloped infrastructure. The infrastructure (equipment, storage and workers etc.) will not be developed without a market. So the first ethanol plants will have to not only create a new technology but also a new market for the raw material used. All this has to be done while facing stiff, well established market competition from corn ethanol and of course the anti ethanol big oil lobby. As I see it, corn ethanol producers and big oil know this stuff. The 21 billion cellulosic ethanol mandate is a sop thrown to the anti corn crowd to placate them and distract their attention from what is really going on. The corn ethanol lobby won big time with a doubling of the mandate for corn ethanol which will bring corn ethanol's production up to near the maximum possible. Beyond that point mitigation of peak oil has to come from a slowing economy, conservation due to higher prices, and unconventional oil and such.

practical - these are excellent insights - I think you're spot on (with exception of big oil being anti corn-ethanol - they probably love it as it increases demand for diesel and natural gas and continues with the liquid fuels infrastructure. In fact, if corn ethanol persists, and cellulosic never lives up to promise, then oil prices will be dramatically higher due to this bill)

What I have been seeing from the one contact I know who is in cellulosic ethanol is that the version that is being persued right now is that from wood, rather than from corn stover or switchgrass or the like, because of the problems you mention. Wood is much easier to transport and store, and there is an established way of marketing it. It seems doubtful to me that there is enough land area to grow all the wood needed - even if marginal land is pushed into service - and wood is harvested after only a few years of growth. The droughts in the Southeast and Southwest will not help the situation.

I agree regarding big oil being anti-ethanol. The largest problem I am aware of is the huge amount of infrastructure that needs to be put in place in advance in order to incorporate more ethanol, whether or not the ethanol really goes on line. This is a big expense that will be wasted (and could have been put to better purposes) if it turns out that the ethanol cannot actually be produced.