Introduction to the MixAlco Process
In this essay, I am going to talk about my graduate school work at Texas A&M. Since leaving A&M there have been a lot of developments related to the technology I worked on, so in the essay following this one I will discuss more details on the nature of the technology and the developments toward commercialization.
My Ag Background
I may have mentioned once or twice that I grew up on a farm in Oklahoma. Farming is still very much a major activity within my extended family, and needless to say I have had a lifelong interest in agriculture. After receiving undergraduate degrees in chemistry and mathematics, I decided to attend graduate school at Texas A&M University. For those who may not know, “A&M” is short for “Agricultural and Mechanical.” Based on my background and the fact that I wasn’t far-removed from the farm, I felt more at home at Texas A&M than at other campuses I visited.
There were two fundamental areas that I was interested in for my graduate school research: Sustainable agriculture and sustainable energy. Within the Department of Chemical Engineering, there wasn’t much going on in the area of sustainable agriculture, but there was some interesting work going on in sustainable energy. There were three professors I was interested in possibly working with: Professor Bruce Dale, now at Michigan State University, Professor James Liao, now at UCLA, and Professor Mark Holtzapple. After looking at the nature of the research and speaking with the professors and their students, I chose Professor Holtzapple as my research advisor.
Life in the Lab
I spent many hours over the following two years in Professor Holtzapple’s labs, working to develop a process called the MixAlco Process. I will get into more details of the process and provide links to background information in the next story. In a nutshell, we were using naturally occurring microbes that could efficiently convert cellulose into chemical intermediates that could be turned into fuels. Our focus when I was there was on the rumen digestive system. Cattle are efficient digesters of cellulose; they eat grass – largely cellulose – and in their digestive system a combination of microbes works to turn the cellulose into acetic, propionic, and butyric acid that the cattle then use for energy. But those acids can also be converted into mixed alcohols – ethanol, propanol, and butanol (and trace amounts of higher alcohols).
Our goal was to replicate the rumen digestive system in the lab, and potentially modify it to optimize the yield of desired products. We collected microbes from a pair of fistulated steers on campus. Somewhere out there is a photograph of me with my arm up to my shoulder in one of those steers collecting fluid for the reactors. There is another of me in a white lab coat running from ostriches, which were being raised in the same area as the steers. You had to be really careful around those ostriches, because they could really hurt when they pecked you. But I digress.
Our feedstock was a combination of municipal solid waste (MSW) and sewage sludge. The sewage sludge provided nutrients for the microbes that were consuming and converting the cellulose in the MSW. One of the themes of my research was to determine optimal sewage sludge inoculation levels for the reactors. I spent an entire Saturday morning once at the city wastewater treatment plant shoveling sewage sludge into my pickup, which we then later spread on Professor Holtzapple’s lawn to dry. (I never did ask how his neighbors reacted to that).
Bio When Bio Wasn’t Cool
We made progress while I was there; the kind of progress that these days would generate multiple press releases. But things were different way back in the ancient days of the early 90′s. The link above on the MixAlco process noted that “Dr. Holtzapple was doing bio when bio wasn’t cool.” So there were no reporters sniffing around asking what we were doing (although that would come later), because the clean tech industry wasn’t like it is today.
We were being partially funded at the time by Hoechst Celanese (who I would go to work for making butanol after graduation) and progress was reported to them – not through press releases. We managed to push the concentration of organics in our reactors up to a higher level than had been reported in the literature, and made good progress on many fronts. I also had the idea at one point to try out termite microbes. It occurred to me that the termite digestive system is one of the most effective at digesting cellulose, and thus mining termite guts seemed promising.
I had mixed success with the termite experiments. I realized afterward that trying to replicate a termite digestive system is probably an extensive research project in itself. At the time, I couldn’t find anything in the literature indicating where anyone had tried it before, so I didn’t have anything to guide me. Maybe I was just ahead of my time with the termite experiments, because fifteen years later I started reading news stories like this one:
I defended my thesis and graduated in 1995. The title of my thesis was Volatile Fatty Acid Fermentation of Lime-Treated Biomass by Rumen Microorganisms. I left Texas A&M to go to work for Hoechst Celanese, but joined my research group the following year in Washington D.C. when we won the 1996 Presidential Green Chemistry Challenge Award.
Since I left Texas A&M, Professor Holtzapple and I have had sporadic contact, but I was mostly out of the loop with the continued development of the process. However, he recently contacted me and sent me some presentations and literature on their current status. I asked him if he would mind if I wrote a story about what they are doing – drawing on the information he sent me – and he agreed.
The technical details and progress toward commercialization will be addressed in the follow-up to this essay.