ST. PAUL, Minn. (AP) — In a workshop in St. Paul, several researchers work to advance the future of sustainable energy.

For almost 15 years, the University of Minnesota's Center for Biorefining has researched ways to convert waste into valuable resources like energy and food.

"We saw so much of this waste and it actually causes a lot of pollution to the environment . it's actually, simply, a waste of the resources," said Roger Ruan, founder and director of the center and a University professor. "We feel like if we can add value to all of this waste, that will be great,"

The center has 20 to 30...