Each day, more than half a million diesel-powered trucks and tractor-trailers roar along Canada's highways, churning out air pollution and greenhouse gases. What if some of those vehicles could be fuelled by non-polluting, renewable biodiesel instead? It's a vision that has captured attention around the world.

The problem? Feedstock. Refined vegetable oils are too expensive to compete with petroleum. However, the cheaper alternatives - derived from used cooking oil and rendered animal fat -…