Steven Chu, the U.S. energy secretary, has deep pockets: $26 billion as his department budget, and another $39 billion of stimulus money. Here is what is “in”: electric cars, a smart electric grid, a new nuclear power fuel cycle. Here is what is “out”: the hydrogen car and continued work on Yucca Mountain. The hope: A nuclear power system can be devised that avoids the generation of long-term nuclear waste.