I read with interest the article on production lags in cellulosic ethanol because I was in that field for a number of years (C&EN, Oct. 10, page 12). The problem with the lag does not come from not locating plants where they can take advantage of sources of cellulose that are currently collected. Locating plants in agricultural settings is not the answer since the wastes are usually not collected; if they are, they are used as silage.
We found in our studies that the most reliably collected source of cellulose is municipal solid waste. We also calculated that it takes a city of 140,000 people to generate enough paper waste to support a 25 million-gal-per-year ethanol plant. The issue with this is that the waste must be air classified. This technology has all the right things going for it: It reduces the load going to the landfill and does not take any food source out of the food chain.
A real effort should be made to couple the air classification of waste with the enzymatic conversion of cellulose to glucose and subsequent fermentation to ethanol or other chemicals if the U.S. wants to meet the goals set for cellulosic ethanol.
By Paul Blotkamp