Tuesday, June 07, 2005

Turning Farm Waste Into Biodiesel

One problem with biodiesel is that it uses relatively little of the plant -- the harvestable fatty acids from the rape plant, for instance -- and yields are too low to realistically grow any but a tiny fraction of the energy needed to replace petroleum diesel. But perhaps not. In this MIT Technology Review article, Dartmouth researchers have found a way to take any cellulosic material and convert it into biodiesel:
The new method is divided into four parts. First, a stream of processed biomass consisting of waters and sugars is fed over a nickel-tin catalyst to strip off some of its hydrogen molecules. Then the stream is treated with acids that take out most of the water. The resulting "goo" is then transported over a solid base catalyst, which forms it into long carbon chains, called alkanes. Finally, those alkanes are run through a platinum-silica-alumina catalyst at high temperatures, while the hydrogen from the first step is fed into the reactor. The resulting liquid has almost the exact same chemical structure as traditionally refined biodiesel and burns the same way in diesel engines. And the only byproducts are water and heat.
As usual, the economic problems remain the principle stumbling blocks, and so we await a commercial version of this process.

Green Car Congress published an article about these guys a little earlier in the month, using the Science source articles.