Joining Tom each weekend with an energy-education brief will be Richard “Dick” Hill of Orono, UM professor emeritus of engineering. Tom’s radio sidekick, Dick has been an expert resource for BDN readers for three decades. Each week, By the Numbers will provide brief explanations of the math and science of energy to help readers understand the efficacy of energy systems. One source he relies on also is available to readers, and that’s the Energy Information Agency of the U.S. Department of Energy.