Every time I fill my gas tank, I see the notice on the pump that explains part of the fuel I’m buying is ethanol — a common biofuel. While biofuels can be good to promote national energy independence and possibly help with greenhouse gas emissions, the ethanol we all buy at gas stations is made from corn. With corn ethanol, we are essentially putting food into our gas tanks, a fact that some people take exception to.
A different way of producing biofuels is to use crop residues and woody materials as the source for the fuel. Those materials are full of cellulose and a molecule called lignin that is bonded to the cellulose within each plant cell. Researchers are looking for a cheap and clean way to neutralize the lignin and break down the cellulose into simple sugars.
We can break down lignin at high temperature and pressure, and with harsh chemicals. But can we find a way to remove the lignin that doesn’t require high costs and harm to the environment?
Researchers are looking at two organisms that can do the needed chemical tricks but at room temperature and pressure and without harsh chemicals. Certain types of fungi can break down cellulose, but fungal action is slow — very slow. So a number of scientists are looking at termites.
As we all know, termites can eat solid wood and make a living doing so. Their digestive systems break down tough plant material at room temperature and pressure in as little as 24 hours.
Termites start breaking down their food when they chew it and coat it with an enzyme. The termites then swallow the material, passing it into a three-part digestive system. By the end of that — in just a day’s time — the lignin is out of the way and the cellulose has been broken down into sugars that the termites live on.
Professor Shulin Chen of Washington State University is one scientist studying what termites do with an eye toward adopting some similar processes to make biofuels from crop residues and woody materials.
“We are studying the mechanisms for how the termite does what it accomplishes in its digestive system,” Chen told me. “The goal is to employ a similar mechanism in an engineered system.”
In other words, we want to learn from the termites and ultimately set up biorefineries that can break down crop residues and woody materials, doing so economically and in a way that doesn’t harm the environment.
“The final goal is to do better than the termite, to do the same basic work but at a faster rate and on a larger scale,” Chen said. “We know the basics of what’s going on in the termite, but we need to nail down some specifics.”
From where I stand when I fill up my gas tank, thinking about pumping food into my engine to be burned there, I’ve got to wish Chen and his team the very best.
Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human, and Natural Resource Sciences at Washington State University.