Cellulosic biofuels

When American farmers proposed reviving the old industrial ethanol program as a way to improve national security in the wake of the Arab oil embargoes in the 1970s, they were ridiculed as crackpots by the automotive and oil industries.  In Congressional testimony, the industries presented evidence that blends of ethanol could damage auto engines and disrupt petroleum refineries.  These arguments might have won out if engineers from other countries, notably Brazil, had not already  proved that these issues could be fairly easily overcome.

The idea that backyard alcohol stills could help decrease dependence on foreign oil had an appeal to President Jimmy Carter, whose idea of the energy crisis as a “moral equivalent of war” implied that civilian mobilization was an essential part of the strategy.  But the hoped-for rural renaissance did not occur, as oil prices fell through the floor in the 1980s. The ethanol industry only took off  following the Clean Air Act of 1990, when environmental concerns forced mandatory shifts away from toxic gasoline octane boosters.

By the year 2010, as the corn ethanol industry topped 10 billion gallons of production from corn per year,  environmental critics began questioning the tax incentives and other protective mechanisms that kept it afloat. Where, they asked, were the second generation biofuels from non-agricultural products that Henry Ford envisioned? What happened to biofuels from cellulosic materials?

The idea of using abundant cellulosic materials for biofuels was most best expressed by Harold Hibbert, a Yale University chemist who, in  a 1921 engineering paper, noted that cellulose could help free the country from depending on Middle Eastern and Russian oil in the coming years.  At the time, the technology for making alcohol from cellulose was a relatively well known byproduct of the paper making process.  A large scale alcohol fuel substitution program during the 1930s in Sweden, for instance, focused on ethanol as a byproduct of the paper industry and specifically prohibited the use of grain or other foodstuffs.  But the technology to produced ethanol on a large scale from cellulosic biomass proved daunting and the costs seemed prohibitive.

An important breakthrough came in the 1940s, with the discovery of cellulose – eating microbes in the remote jungles of the Pacific.  Soldiers called it “jungle rot,” but  Elwyn T. Reese  and others in the US Army labs realized that the enzyme from the fungus was turning cotton into sugar by splitting the strong chemical bond holding cellulose molecule together.   Scientists told Congressional committees in the 1970s that they could produce fuel from cellulose at low cost, and without affecting food supplies. Research  continued in hundreds of university and government labs, and thousands of unrecognized scientists took small steps, isolating, characterizing and testing the complex chemical structures of plants, which includes not only cellulose (linear sets of six-carbon glucose molecules in strong bond) but also five carbon sugars (hemicellulose) and glue-like substances (lignin).

The enzyme process for biofuels was the basis of government-subsidized plants in the US, Denmark and Canada early in the 21st century, but the process proved difficult to regulate, and the hoped-for breakthrough into low-cost, non-food biofuels proved elusive. Meanwhile, research into third generation biofuels involved the genetic engineering of plants that could be processed more efficiently.  Other avenues of research included the conversion of oil seed plants into substitutes for diesel fuel. This was especially significant for developing nations such as Haiti, where deforestation and poor agricultural practices had left land that was worthless for food production.


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