Energy enthusiasts

The problem
THE TRANSPORT AND storage of energy is one of the main challenges of life. Creatures hunt and consume each other, stealing nutrients. Life constantly juggles energy: lifeforms evolve in order to change energy from one form to another, and store it away in their bodies. In particular, carbohydrates and fats are Mother Nature’s biological batteries.
Modern society has the same set of problems. We fight over resources; we mine fuels, like coal and petroleum; we extract energy from dams and wind farms. Then we store energy on power grids, in batteries or in the fuel tanks of our cars until we need it.
But humanity’s current sources of energy can’t sustain our needs. We need to access large amounts of energy that have been efficiently stored.

The researchers
André Tremblay and Marc Dubé are a pair of professors at the University of Ottawa whose research interests overlap when it comes to biofuels.

The project
Biodiesel is made from fatty acids produced from vegetable oils, animal fats, algae, or even waste grease. Amazingly, biodiesel can be used in current diesel engines without any modifications.
But the production of biodiesel is a remarkably difficult venture. What’s needed is a simple, single-step process that can continuously produce high-purity fuel without leaving residual gunk in the resultant.
Tremblay and Dubé have been working on a process to do just that.

The key
The reaction that turns waste grease into biodiesel is called transesterification. This reaction occurs at the surface of oil droplets mixed in alcohol. The transformation of oil into biodiesel is fast at first, when there’s very little fuel in the alcohol, but becomes less and less efficient as the alcohol becomes saturated with biodiesel.
To counter this, Tremblay and Dubé purify the results as the reaction occurs rather than after it. The oil flows through a reactor pipe. The pipe is formed by a ceramic membrane with tiny pores too small for the droplets to escape through. The biodiesel, on the other hand, can per- meate the reactor membrane easily.
What’s left? Lots of oil droplets in the reactor that are continually undergoing efficient transesterification on one side of the membrane and high purity biodiesel on the other.