The Detroit Zoo says it will running 100% on renewable energy in 2020. The effort adds to other sustainability efforts that have made the zoo a leader in environmental stewardship. In this 'Issues of the Environment' conversation with 89.1 WEMU's David Fair, Detroit Zoological Society CEO Ronald Kagen covers what environmentally-friendly features exist, what is to come, and how the zoo is spreading its message to all who will listen.