An Indispensable Truth: How Fusion Power Can Save the Planet

"Maybe. I chose this book because it’s written by a physicist, very elderly now, who has spent all his life working in controlled fusion. The title is a take on Al Gore’s An Inconvenient Truth . The first part of the book is Chen claiming that fusion is indispensable for our future, and why. He has a very readable section on climate change, a section on fossil fueled energy and a section on renewables—in which I disagree with him strongly, because he denigrates solar energy—and then goes on to say that we need fusion. The second half of the book is about fusion. It gets very thick into quite significant nuclear physics and is very hard to read for the average person. It would be a good skim to get a sense of it, but the book is bipolar in that way: it’s got a first part that’s readable by anybody and then the second part goes into deep details of why nuclear fusion is complicated to make happen. “There are really only two long-term viable sources of energy for humankind. One is solar…The other is nuclear fusion” Now, you wanted my opinion. My view of the world 100 years from now, in terms of energy—if we muddle through everything else we’ve got to muddle through—is that there are really only two long-term viable sources of energy for humankind. One is solar. This is not some tree-hugging environmentalist’s dream: there is 10,000 times as much solar energy coming to the planet as we use. It’s a colossal amount and it’s going to go on for 5 billion years, for as long as the Sun continues to shine. That’s one possibility. The other is nuclear fusion. Even though we haven’t figured out how to make power plants with nuclear fusion, we are inching very, very, very slowly toward that. Many of my fellow scientists think it’s a pie in the sky. I don’t happen to agree. I don’t know that it’s going to work but I’m mildly enthusiastic. If we get fusion to work, a gallon of seawater has the energy equivalent of 350 gallons of gasoline. That’s worth pursuing, it seems to me. I agree with Chen there. Fusion is an almost inexhaustible source of energy. In fact, the energy in seawater would last probably about four or five times as long as the Sun is going to shine. If we’re worried about what happens to Earth after the Sun goes out—and assuming we can move our orbit away from it so we won’t be engulfed by it when it expands—we have, in the oceans, four or five times as much time. But that’s a long way off. The nuclear power we get today from our nuclear reactors is provided by splitting the nuclei of uranium atoms, and plutonium, to some extent. That’s one way of releasing energy from the atomic nucleus, because if you go to a nucleus that’s smaller than uranium, about half the size of uranium, you release energy in that process. But you also release energy if you go from very light nuclei, like helium and hydrogen, to heavier nuclei like lithium and carbon. This is how the Sun works. The Sun makes its energy by fusing these lighter nuclei. We know how to make that happen on Earth, in our so-called ‘hydrogen bombs’, which are fusion weapons or partly fusion weapons. But we don’t know how to control it in a power plant. That’s what we’re working toward. The reason there’s so much fuel available for fusion is it uses hydrogen, which is part of water. It uses a special kind of hydrogen (called deuterium), which is only one in 6500 atoms of hydrogen, but that’s still a lot of atoms in the oceans. So that’s what fusion is: joining of lighter nuclei to make heavier ones. It’s what powers all the stars. It’s what made the elements that you and I and planet Earth are made of. They were all forged in these fusion reactions occurring in ancient stars. So fusion is a big, big player in the universe. The fission that we use for our nuclear power plants is not a very big player. It doesn’t happen naturally, except in some very rare occasions. It’s become more exciting in recent years, with two developments. One is the international collaboration that is building the ITER experimental reactor in France. A number of countries are involved in that, including the UK, the US, Russia, China and a lot of others. It’s a huge international collaboration building this reactor, which was originally supposed to be working in 2025. It’s now been put off till 2035, before it starts to generate fusion energy. It’s an enormously expensive project. Partly because of the enormity of that project, other ideas have taken hold among small startups that are also trying to develop cheaper, faster fusion energy. Who knows whether any of them will succeed? Some of them look mildly promising, but they have so many challenges to overcome. We don’t know yet. We are making some progress. It’s a more exciting time for fusion than it was 10, 15, or 20 years ago. On the other hand, in the 1950s the argument was, ‘We’ll have fusion in 20 years.’ It’s sort of always been ‘we’ll have fusion in 20 years’ and we’re not getting any closer. I don’t know of any physicists who are rushing out to join the fusion effort, but I do know people who work in fusion and it’s an exciting area."