"Whither cellulosic ethanol?" by John Benemann and Don Augenstein

Regarding lignocellulosic ethanol, we are skeptics.  This technology is not ready for policy decisions.  The real issue of course is, does the technology for converting lignocellulosic biomass to ethanol work now, or can it be made to work in short order, or can we predict when and if it will work with any assurance? 

There is an absence of any arguments or even information based on the technology itself in the discussion about lignocellulosic ethanol.  I (John) am among other things a biotechnologist, and very familiar with the associated chemical engineering issues.   I would have expected at least some mention of past and recent experiences, of problems, such as needs for extensive feedstock pretreatment, or of problems with fermentations of the pentoses, about the enzymes.  Nothing. 

We strongly support R&D in this field.  Money would be better spent on that than on just one commercial plant.  And, let me hasten to add, that it is perfectly possible to make ethanol from lignocellulosic biomass, it's just currently very inefficient and expensive.  The Soviets had some wood-to-ethanol plants running during WWII, when efficiency and economics did not matter as much, which they kept going afterwards, with at least one going on until the Soviet Union collapsed.   Not a pretty technology, without even looking at the energy balance (cheap coal or then-cheap Soviet natural gas, converted to expensive state subsidized ethanol, an economic model now also adopted for corn ethanol here in the US.)

And we, in the U.S., even made butanol from seaweed harvested off San Diego during WWI, in a major industrial enterprise that was set up in a few months.  This is a perfect example of necessity being the mother of invention, and showing how fast we can do something when we need to, for our survival.  But extrapolating from making ingredients for munitions during a war to making transportation fuels for civilians driving SUVs is more than a bit of a reality stretch.  The analogy was made elsewhere of this being the difference between going to the Moon and Mars.  Of course, we still haven't figured out why to even go to the Moon, aside from the feel-good factor.

Bottom line, making ethanol from lignocellulosics is a technical issue, actually many separate technical issues: can we really make 60 or 80 or 100 gallons of ethanol per ton of biomass?  Can we really ferment pentoses outside the laboratory with genetically engineered strains?  Will we have a positive energy balance and not just run this on fossil fuel, as we do corn ethanol?  And, coming to the details, can we really use commercial enzymes?  Or can we use the same fermentation vessels that are used in the corn ethanol business, or conversely, do we need to go to very, very expensive contained fermentations?

And at the end, do we get a high enough ethanol content in the fermentation beer (close to 10%) to have a reasonable distillation cost?   And, finally, can we put it all together, starting with the necessary pretreatment of lignocellulose (and what kind at what cost?).  There are more questions than answers now.

Actually, some applications for particular, minor, biomass waste resources could make ethanol now at food processing plants, breweries and such.

However, visions of over a hundred billions of gallons ethanol per year from biomass must, by all reasonable analysis, be considered a distant and uncertain possibility not an imminent accomplishment, as is being portrayed. That is the bottom line.

Of course, reasonable researchers will argue about exactly where we are and when and how can we could get to where we are going.  As one close colleague told us, all the technical problems we talk about are actually viewed as "opportunities" by the R&D community.  We agree, but there is now the belief that with current high ethanol prices, we have the means to this end at hand.   After all, if for the past 25 years we were almost there, according to the National Renewable Energy Laboratory and others working on this, it stands to reason that with gasoline and ethanol prices two or three times that high we must now be in clover. Right?

Wrong - that is the rub of it.  We aren't really any closer than before.  Yes, we can, on paper, shave down the projected costs to reach very low, low costs for lignocellulosic ethanol.   But the same required assumptions are still there, slightly closer to but still too far away for reality.

At present there is only one pilot plant operating, by the Iogen Corp. in Canada, which is producing, according to their own statements, at a quarter of initially announced capacity.  That is all we really can, and actually need, say about the commercial status of this technology.

Thus jumping on this bandwagon and joining in the suspension of disbelief, which seems to pervade public discourse, with exception of a few, is premature.

There is more to this argument, however, than just the issue of whether there is real technology (real could be defined, loosely as less than $5/gallon of ethanol, or over  $300/barrel of oil equivalent, or at least within a factor of two of that).  The most important question is: what is a better way to use our billion plus ton per year potential biomass resource; conversion to ethanol or use for other purposes?  Would it not be better to use surplus and waste wood, crop residues, or energy crops (another whole subject) to heat our homes, using wood pellets or even gasification to make heating oils? 

And if we really do want ethanol from crops, and we certainly favor some, 10%, to 20%, of our gasoline to be replaced by ethanol in the longer term, if reasonably economically or energetically feasible, would it not be better to grow high starch crops (requiring lower fertilizer inputs than corn)?  Then we can make ethanol the way we know how, while using part of the crop residues for the process heat, rather than coal or natural gas. That should be an improvement what we are doing now, the corn to ethanol fiasco.

And a final question, should we, including our venture capitalists, foist on to other countries, let me give India as an example I know of personally, our simultaneously myopic energy policy and visionary technology focus? The answers to this and the prior questions are apparent, they hardly need to be answered, but they are not being sufficiently asked.  Bluntly, we should not put our trust and future in ethanol from biomass saving the day. 

Reasonable people can argue the merits of this case, but these merits, particularly the technical nitty gritty, have not been argued to the extent necessary.   We hope to add to this debate, in a minor way, by pointing this out, and also pointing to some of the technical issues.  We propose that ethanol from lignocellulosics is not something we should count on, any more than most of the other 1970s and 1980s ideas and technologies being re-floated (biodiesel from algae being a personal favorite of John’s).

Yes, biofuels are and will be very important, we are already doing some things, and need to do much more. Much work is required, in many areas, from anaerobic digestion to crop production, and including R&D on lignocellulosics to ethanol.  Maybe we will get the proverbial breakthroughs.  But multiple barriers must be overcome, and betting the farm on just this one ticket, on only ethanol from switchgrass or corn stover, and such, is foolish in the extreme.

(Source:  Drs. Benemann and Augenstein are affiliated with the Institute for Environmental Management of Palo Alto, Ca. and have worked in the field of biofuels and analyses of fuels from biomass processes for over 3 decades.  They are biotechnologists/chemical engineers and have developed ongoing methane-from-waste processes projects. They have worked on biofuels projects for Exxon, EPRI and others. This article has appeared previously and is reproduced with the author’s permission. 

Contact: John Benemann, Institute for Environmental Management, telephone:  (925) 939 5864, email:  jbenemann@aol.com