The process could both greatly reduce greenhouse gas emissions and increase the amount of fuel that can be made from an acre of biomass using gasification. Many companies are pursuing biological approaches to converting biomass into fuel (using enzymes and yeast, for example), rather than thermochemical methods such as gasification, in part because biological approaches tend to convert more biomass into the desired fuel than thermochemical methods. But biological approaches are each designed to work with just one type of biomass. Gasification has the advantage of being more flexible. The same facility could potentially process grass, wood, and even old tires.
The researchers found that to make the process work, it was necessary to precisely balance three variables: the amount of carbon dioxide, the amount of oxygen added, and the amount of methane relative to the amount of cellulose–a material derived from biomass. The mixture is fed into a high-temperature reactor that consists of a rhodium- and cerium-based catalyst. In the reactor, particles of cellulose are quickly converted into a liquid, which spreads over the catalyst, enhancing the reactions that lead to the production of hydrogen and carbon monoxide gases.
Paul Dauenhauer, a professor of chemical engineering at UMass Amherst, and one of the researchers involved in developing the new process, says 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 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, he says. 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.