Is Fusion Energy in Our Near Future?

John Holdren has heard the old joke a million times: fusion energy is 30 years away—and always will be. Despite the broken promises, Holdren, who early in his career worked as a physicist on fusion power, believes passionately that fusion research has been worth the billions spent over the past few decades—and that the work should continue. In December, Scientific American talked with Holdren, outgoing director of the federal Office of Science and Technology Policy, to discuss the Obama administration's science legacy. An edited excerpt of his thoughts on the U.S.'s energy investments follows.