Over at The Oil Drum, there's an insightful article by Robert Rapier, a chemical engineer and blogger:
Cellulosic Ethanol Reality Begins to Set In
The Oil Drum concerns itself with energy issues of all kinds, but leans toward Peak Oil and alternative fuels. It's not a site that merely passes through propaganda for the fossil fuel industries.
Rapier, who has hands-on experience with cellulosic ethanol, is skeptical that cellulosic ethanol can ever be a commercial process because of the low energy density compared with conventional fossil fuels.
It is hard to believe that just a few short years ago, Congress mandated a massive increase in usage of cellulosic ethanol. This was remarkable, because no commercial cellulosic ethanol facilities even existed at the time. But people like Vinod Khosla were busy testifying before Congress that the only thing holding the industry back was more funding, and if they would provide the funding we could replace all of our gasoline consumption with cellulosic ethanol.
So Congress mandated in the 2007 Energy Independence and Security Act that we would use 100 million gallons of cellulosic ethanol in 2010, 250 million gallons in 2011, and then rapidly expand to 16 billion gallons per year by 2022. At the time, I saw a very appropriate analogy that summed up the situation: “It’s like trying to solve a traffic problem by mandating hovercraft. Except we don’t have hovercraft.” [Emphasis added]
The article goes on to explain that the main problem with biomass as a feedstock for cellulosic ethanol is its low energy density. It's the energy lost in transporting the enormous quantity of feedstock to processing sites that seems to be the Achilles heel of the process.
Personally, I don’t believe large-scale commercialization of cellulosic ethanol will ever be viable due to the aforementioned fundamental issues with biomass conversion and efficiency, and will ultimately be relegated to the role of a niche fuel provider ... . The heart of the problem here was the idea that technology can be mandated. Imagine that in 2005 Congress put forward a mandate that lung cancer would be cured by 2010, breast cancer by 2012, and by 2020 all cancers would be cured. People would think they were absolutely daft, because more people understand the difficulties involved in coping with cancer. On the other hand the general public doesn’t have a clue of the difficulties in economically turning cellulose into fuel, but they did hear a lot of hypesters in the news saying that it would be easy — as long as you get that Silicon Valley “know how” working on the problem. But the Silicon Valley players learned that Moore’s Law doesn’t apply to the energy business.
It is great to have lofty goals, but when you start to base your energy policy on fairy dust, you are setting yourself up for massive problems down the road. Technology breakthroughs can’t simply be mandated. Sometimes critical breakthroughs happen, and sometimes they don’t. In the case of cellulosic ethanol, commercial viability remains out of sight.
I am reminded of the story of the state legislature that passed a measure that henceforth the value of pi was set to 3, thereby simplifying grade school math for future generations of students.
It's apparent from Mr. Rapier's analysis that a commitment to cellulosic ethanol as a fuel source would turn our nation into a giant compost pile. Another option would be to eschew the internal combustion engine altogether and return to horse-drawn conveyance. That would require a willingness to spend our lives knee-deep in horses**t, but given that our governmental leadership and its policies have us neck-deep in same, the equine option may be a distinct improvement.