Issue Date: March 12, 2007
Products From Biomass
I must agree with David Pimentel and Lester Brown (C&EN, Jan. 1, page 19). As a graduate student in 1943, I was given the project to ferment sugars from the acid hydrolysis of wood into ethanol. For the next 13 years I made food yeast, lactic acid from sugars in paper mill waste, nitrogen-carrying fertilizer from lignin residues, and finally pilot-plant production of levulinic acid from spent wood from naval stores production.
However, these products from biomass have one thing in common and that is a cheap source of raw material, such as bagasse, peanut shells, sawdust, garbage, and so forth. Fifty years ago, it cost, $8.00 per ton to collect pine stump wood and transport it to the plant.
Bringing small, portable plants to the raw material might help. During World War II, Seagram's engineers devised a working corn-to-ethanol process for railroad cars. A model was displayed at a show in Chicago.
It is most unfortunate that food items are being converted to liquid fuel.
Reid H. Leonard
The ethanol-from-corn industry, buoyed and pushed by massive governmental subsidies and relentless pressure from Cargill and ADM (who are to every aspect of corn growing and usage what paint is to a frame house—they cover it), seemingly moves inexorably forward.
Inexorable though it may be, we can and should ask questions. Is the energy obtained from ethanol from corn less than the energy required for its production? Do we care enough about the indisputable negative environmental impact?
Concerning the first question, the National Corn Growers Association (NCGA) would have us believe it is "an unrealistic academic exercise with little value for public policy debate" to seek a way to produce ethanol with a sufficient net positive energy so that gasoline can be replaced.
But it behooves academicians and others who enjoy academic freedom and can engage in "academic exercises" (quoting NCGA) to think outside the relatively narrow box of corporative corn farming and continue searching for answers.
The second question has several ramifications, one of which is sustainability (a word that implies circularity and giving back what has been taken). Soil erosion as well as depletion and the dead zone in the Gulf of Mexico belie any semblance of a sustainable corn-growing industry.
The title of Jeff Johnson's article, "Ethanol—Is It Worth It?" asks a serious but more general question, one worthy of a straight answer. It is a good piece of writing generally, but the title's question is only rhetorical. The best approach to an answer comes in the last paragraph: "What's clear is that corn-based feedstock is likely to be the start of a biofuels market, not its end."
R. A. D. Wentworth
William M. Wentworth
One hates to be considered a curmudgeon, but I will chance it. I am a retired biochemical engineer; my undergraduate years were 1952-56. I can recall reading about cellulose-to-ethanol conversion attempts then with the view that the conversion would become reality in "the next four to six years." If memory serves, a pilot plant was built at Natick (or perhaps it was Massachusetts Institute of Technology) to prove the concept. The current hope for success is worthy, but this curmudgeon wouldn't bet on it.
Harold B. Reisman
In his letter, Gerald J. Mantell asserts that the energy balance for the production of ethanol from corn is "negative," and this needs to be examined (C&EN, Jan. 8, page 4). I am not sure what is meant by "energy balance" here, but a more helpful index is energy return on energy invested (EROEI). This index cannot be negative, but a value of less than 1 for production of a particular fuel usually means that fuel is nonviable.
In the Oct. 2, 2006, Energy Bulletin, Milton Maciel gives an EROEI value for corn alcohol of 1.3 (www.energybulletin.net/21064.html). Of course, this is not a hard number and precautions such as reduction of heat losses from the production plant can improve the EROEI of a fuel-making process.
The Energy Bulletin information should be taken to mean that values of 1.3 are currently being realized.
J. C. Jones
University of Aberdeen, U.K.
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