In the rolling hills of East Tennessee, a team of scientists and engineers is working to create a sun on Earth. They’re at Oak Ridge National Laboratory, once an integral part of the Manhattan Project’s experiments with nuclear fission. More than 70 years later, these 100-odd researchers are focused on nuclear fusion, the other side of that atomic coin. They say they and their counterparts in the European Union, Russia, and China are less than a decade away from a successful demo of the technology needed to build a reactor that generates a city’s worth of energy and emits zero carbon.
The project in Tennessee feeds into work on the International Thermonuclear Experimental Reactor, or ITER, a collaboration among 35 countries that’s under construction in the south of France. Pretty much every expert in the field says the project is a sure thing. By 2025, the consensus goes, the scientific joint venture should be able to create and sustain a fusion reaction that produces more energy than it took to start, a major step toward making fusion a sustainable way to run the world’s power plants. And all for roughly $20 billion, about what the U.S. spent, adjusted for inflation, to build Oak Ridge in the 1940s.
“With twice the money, we can definitely do it twice as fast”
“It’s not just empty words, it’s actually a reality,” says Ned Sauthoff, the plasma physicist heading the U.S. research unit. “The scientific principles have been demonstrated, and it’s a matter now of raising it to industrial scale”—one at which 5 pounds of hydrogen, a raw material readily available everywhere, can yield the same amount of energy as 90 railroad cars full of coal.
The biggest obstacle to the world’s fusion-energy future is funding, Sauthoff says. The U.S. has spent more than $1 billion on ITER since its 2006 inception, according to a 2016 report from the U.S. Department of Energy, but that leaves about $3.5 billion of its commitment left to allocate, and federal investments in fusion research are waning. For next year’s budget, the Trump administration has recommended that Congress allocate less than half of what Sauthoff says he needs to keep ITER on track for 2025.
“There are some things where you’re paced by ideas, and there’s some things where you’re paced by money,” says Sauthoff, 68, with the air of a science teacher who wants to tell you everything he knows. He speaks slowly but with gusto, his left eyebrow occasionally perking up to drive home a point. “I’m not saying that with 10 times the money we could do it 10 times as fast,” he says. “But with twice the money, we can definitely do it twice as fast.” The Energy Department didn’t respond to a request for comment.
The ITER researchers are designing their fusion reactor to produce a series of self-sustaining nuclear reactions, known as a burning plasma. Inside the reactor’s core, heavy hydrogen atoms—those carrying one or two extra neutrons—will be pressurized and heated to 100 million to 150 million degrees Celsius. In this plasma state, the atoms’ component particles start to move much faster and more freely, enough so that particles that typically repel one another get close enough to fuse together. This reaction yields a lot of heat, which conventional power plant turbines can convert into electricity.
The sun captures and confines this plasma with its intense gravitational force. ITER plans to do it using a doughnut-shaped reactor called a tokamak, which contains the energy using strong electromagnetic fields generated by giant superconducting magnets. Of the 200-plus tokamaks built in the past few decades, none has been able to generate more energy than it consumes. ITER, the biggest tokamak yet, is designed to be the first self-sustaining one. Its developers say it’ll produce 500 megawatts of power using 50 megawatts to get the reaction going. That output could power a city of 375,000 homes for the foreseeable future while producing a fraction of the waste that today’s fission plants do.
While fusion has been a fixture of the nerdier parts of the popular imagination for decades, interest in creating a burning plasma peaked after the oil shortages of the 1970s. Since then, money problems have shut down promising experiments and stunted progress more than once, says Sauthoff, who experienced some of those disappointments firsthand. Eighty-five percent of U.S. energy consumption still comes from the major hydrocarbons: oil, gas, and coal.
As with solar and wind power, America’s abundant energy reserves and fossil fuel interests have kept the country from treating fusion as an urgent imperative. Lawmakers also have a tough time spending money on long-term projects, says Samuel Brinton, director at Core Solutions Consulting, who advises government officials on nuclear issues. He estimates that cutting U.S. funding to ITER by half would delay the project by 15 years or more. At Oak Ridge, Sauthoff and his team are scrambling to figure out how to cope with shrinking budgets, which delay their delivery of components to France.
Even when the ITER funding was in less danger, things didn’t always go according to plan. The project, which originally was supposed to be producing plasma by 2013, has been plagued by cost overruns, technical delays, and what the U.S. Government Accountability Office called management deficiencies. (ITER didn’t respond to a request for comment.) Since 2015, a new director-general, French nuclear physicist Bernard Bigot, has helped turn the project around and justify further U.S. investment, former Secretary of Energy Ernest Moniz wrote in a report to President Obama last year.
ITER isn’t the world’s only nuclear fusion project. Several efforts funded by private investors are experimenting with different approaches and designs. But the consensus among the industry’s scientists remains that the project in the south of France stands the best chance of success. “ITER will deliver,” says Juergen Rapp, a plasma physicist who works at Oak Ridge but isn’t involved in the ITER project.
The more cost-cutting the government does in the short run, the more will have to be spent in the end to accommodate lost productivity, says Sauthoff. “If you’re underfunded, you also waste money,” he says. “I get frustrated when I know that we can do things better, faster, and cheaper.”Nguồn: www.bloomberg.com