As in today’s coal-fired power plants, the ultimate object is heat — to turn water into steam that drives generators. Fusion, however, produces no greenhouse gases, no long-lived nuclear waste and no risk of the sort of runaway reaction that occurred at Fukushima. Fusion research here and elsewhere is supported by nations with half the world’s population — China, India, Japan, Russia, South Korea and the European Union. The current domestic spending pace would cost $2.5 billion over 10 years — about one-thirtieth of what may be squandered in California on a 19th-century technology (a train). By one estimate, to bring about a working fusion reactor in 20 years would cost $30 billion — approximately the cost of one week of U.S. energy consumption.

Given the societal will, commercially feasible production of fusion energy is possible in the lifetime of most people now living. The cost of operating the PPPL complex, which a century from now might be designated a historic site, is 0.01 percent of U.S. energy spending. PPPL’s budget is a minuscule fraction of U.S. energy infrastructure investment (power plants, pipelines). Yet the laboratory, which once had a staff of 1,400, today has only 450.