The picture of our present-day energy use comes from a sort of all-of-the-above menu. We use oil, gas, natural gas, nuclear, wind and solar. Research is underway to determine if the use of hydrogen can be used to significant scale as part of the energy diet. Ann Arbor has become central to the research and discussion on that matter. On this week’s “Issues of the Environment,” WEMU’s David Fair was joined by the Associate Dean for Research at the University of Michigan College of Engineering, Todd Allen. They explored the environmental promise, uncertainties and controversies surrounding hydrogen energy.