According to an article in the highly respected Technology Review, published by the Massachusetts Institute of Technology, a special method of “gasification,” developed by researchers at the University of Massachusetts Amherst and University of Minnesota for converting biofuel feedstock into sustainable fuel, could have a “profound” effect on the chemical industry. The process would not only greatly reduce greenhouse gas emissions, but double the amount of fuel that can be made from an acre of biomass feedstock.
“The article in the Technology Review shows that, if you utilize our new technique for gasification during the catalytic process for converting biomass,” says Paul Dauenhauer of the UMass Amherst Chemical Engineering Department, “you can actually use 100 percent of the carbon in that biomass for making biofuels.” That percentage doubles the proportion of fuel-producing carbon produced in any previous gasification process done in one reactor while converting biomass to biofuels.
"In the chemical industry, even a few percent improvement makes a big impact,” says Dionisios Vlachos, the director of the Catalysis Center for Energy Innovation at the University of Delaware, in the Technology Review article. “The increase from 50 percent to 100 percent is profound."
It could be especially profound considering the high stakes. “Our ability to provide fuels and chemicals in a sustainable manner for future generations presents the largest global challenge for reaction engineering in the 21st century,” says Dauenhauer.
The new technique, when perfected in as few as two years, would be a major step forward in the quest for a production-ready process to convert biomass to biofuel. As the Technology Review article explains, “Biomass can be converted to fuels via a process called gasification, which uses high temperatures to break feedstock down into carbon monoxide and hydrogen, which can then be made into various fuels, including hydrocarbons. But there's a major drawback – about half of the carbon in the biomass gets converted to carbon dioxide rather than into carbon monoxide, a precursor for fuels. Now researchers at the University of Minnesota and the University of Massachusetts Amherst have developed a method for gasifying biomass that converts all of the carbon into carbon monoxide.”
In the new approach, the researchers gasify biomass in the presence of precisely controlled amounts of carbon dioxide and methane in a special catalytic reactor developed by the research team. The result is that all the carbon in both the biomass and the methane is converted to carbon monoxide.
As explained by the Technology Review, “To increase the yields from gasification, the researchers add carbon dioxide, which promotes a well-known reaction: the carbon dioxide combines with hydrogen to produce water and carbon monoxide. But adding carbon dioxide isn't enough to convert all of the carbon in biomass into carbon monoxide instead of carbon dioxide. It's also necessary to add hydrogen, which helps in part by providing the energy needed to drive the reactions. It's long been possible to do each of these steps in separate chemical reactors. The researchers' innovation was to find a way to combine all of these reactions in a single reactor, the key to making the process affordable.”
Dauenhauer explains that there are several ways to convert biomass to biofuels, including biological and thermo-chemical techniques. One of those routes is pyrolysis of biomass, or gasification, which are really the same thing. The question is how you can improve that technology. One of the ways is to control the “breakdown environment.”
“If your wood’s in your fireplace, and it is burning at its own rate, you’re not really controlling the chemistry,” says Dauenhauer. “So one way to control that environment is to have very good heat control, and then direct the chemistry with catalysts. So in 2005, while I was at the University of Minnesota, I started working on ways to combine high-temperature pyrolysis with catalysts.”
By 2007, Dauenhauer knew the specific requirements needed to pyrolyze wood or grasses or other biofuels and keep the catalytic particles, which are metal, clean so they can be used continuously.
“Now that I know how to combine these two things, pyrolysis and catalysis, I’m working on directing them to do precisely what I want,” says Dauenhauer.
A commercial version of the process could be set up near an existing natural gas power plant, which would provide ready access to methane and carbon dioxide. But, as the Technology Review notes, the process isn't yet ready for commercialization. The researchers will need to demonstrate that it works with biomass, not just with cellulose derived from biomass. Biomass contains various contaminants not found in pure cellulose. Those contaminants could have a negative effect on the catalyst, and this could make it necessary to reengineer the reactor. And there could be challenges scaling up the process, including ensuring that heat moves through the reactor the same way it does on a small scale.
Dauenhauer notes that the above challenges are minor compared to what his research team has already overcome: “If you have an industrial facility developing this process, I believe it could be brought to market within a couple of years.”