Fast forward to fusion

摘要

Unlimited clean energy produced by the reaction that powers the sun: that has always been the goal of fusion research. But will it ever happen? Since the 1960s scientists have been saying that fusion power could be achieved here on Earth within a 40 to 50-year time frame. Some say it is still 40 years away - and that it will always be just out of reach. When I joined the UK government as chief scientific adviser in 2000, I too was a sceptic. But after making a detailed investigation, I have changed my mind. The concept of fusion power is simple. Heat a mix of hydrogen isotopes to temperatures in excess of 100 million degrees and their nuclei will fuse, producing helium and colossal amounts of energy. Scientists discovered decades ago that powerful electromagnetic rings, or tokamaks, could be used to contain such hot plasmas. The trouble until recently was that experimental fusion reactors always consumed more energy than they gave out: it took more energy to heat the gas to fusion temperature, and keep it there, than was produced by any fusion.