Denver Zoo planned to turn dung into energy

A decade or so ago, Denver Zoo leaders had an innovative idea. As part of their quest to become “the greenest zoo in the country” and a zero-waste facility by 2025, they would develop a technique to transform elephant dung and other waste at the zoo such as paper plates and dirty diapers into fuel pellets that would generate electricity through a process called gasification.
The power would help light and heat the 10-acre elephant exhibit and warm pools in which the animals wade and