“Break-even” is the goal of all fusion researchers. This is the point at which the amount of energy coming out of the fusion reactions equals the amount of energy needed to maintain the plasma. No fusion experiment has yet reached that point. More distant still is a reactor able to generate substantially more energy than it consumes. An economically viable fusion power plant would probably have to do 30 times better than break-even.
Wurden’s two big rivals have a reasonable shot at reaching or surpassing break-even within a decade. ITER, funded by the United States, the European Union, Russia, China, India, Japan, and South Korea, is scheduled to run its first fusion experiments in 2018 or 2019. It will use the most advanced in a line of fusion machines called TOKAMAKS, an acronym for the Russian phrase meaning “toroidal chamber with magnetic coils.” Many physicists see TOKAMAKS as the most promising path to fusion energy. Inside ITER’s enormous, doughnut-shaped reactor walls, magnetic fields, electric currents, microwaves, and particle beams will heat a deuterium-tritium plasma to fusion temperatures for about 20 minutes. During that time, ITER’s designers anticipate that the reactor will put out 500 megawatts of power while using only 50 megawatts, a tenfold energy gain.
The National Ignition Facility at Lawrence Livermore National Laboratory, located 45 miles east of San Francisco, houses the world’s most powerful lasers, 192 of them. Sometime within the next year or two, for a few billionths of a second, those beams will focus 500 trillion watts on a pellet of deuterium and tritium housed inside a little capsule about the size of an Advil tablet. If all works as expected, the deuterium and tritium will slam together at about a million miles per hour, forming a plasma, fusing, and perhaps producing a net energy gain.
Wurden thinks his team has a shot at beating ITER to the break-even finish line, but only if he can scrounge up a little more cash. “We can’t do it with the funding we have now,” he says. “The Department of Energy sponsors all the magnetic fusion research in the country. Alternate projects like ours are at best about 10 percent of the budget, maybe $20 million divided among 10 universities and a couple of national labs.”
Despite the way the government is placing its bets, canned fusion has potential advantages over both of the big projects. It falls somewhere between NIF and ITER in its strategy. Wurden expects his experiment to create a plasma higher in density than ITER’s but lower than NIF’s compressed-pellet plasma. Dense plasmas favor more fusion reactions; so do longer confinement times—but sun-hot plasmas are exceedingly difficult to control. Wurden will trap his plasma for a few millionths of a second. ITER, with its less dense plasma, will need to confine it for full seconds at a time. NIF requires just billionths of a second, but at the cost of enormous energy output from its high-power lasers, which can fire only two or three times a day because they need many hours to cool down.
Canned fusion, if it works, would need less power than NIF and shorter plasma-confinement times than ITER; as a result, a working reactor based on its principles might cost tens of millions of dollars rather than billions. If fusion is ever going to make commercial sense, that is exactly the kind of economic breakthrough it will require.
Even if NIF beats canned fusion to break-even, Wurden thinks his approach will be more practical in the long run. NIF’s lasers currently fire just two or three times a day. It takes 30 minutes just to position the fuel capsule. A commercial laser fusion reactor might have to fire about 15 times a second.
“There’s another problem,” Wurden says. “NIF’s targets are cryogenic”—the fuel pellets are frozen to –255 degrees Celsius—“and in a power plant your poor little frozen target would have to fly into this nuclear hell and not get burned up on the way in. It’s a big problem. There are a lot of questions as to whether you could do this at any cost. With magnetized target fusion, we talk about firing once every 10 seconds. We have a lot of problems too, but we’re not talking about 15 times a second. There are a lot of reality checks that need to be done for anybody’s reactor proposal.”
For a reality check on Shiva Star, I spoke with Jaeyoung Park, an experimental physicist who has taken leave from Los Alamos to join a small team in Santa Fe that is pursuing its own fusion research. His biggest concern is that Wurden may not be able to contain the deuterium plasma long enough. “It’s very difficult to squeeze the plasma uniformly—the squeezing has to be fast and furious,” Park says. “And heat losses might make it impossible for the plasma to achieve the high temperatures needed for fusion. But Glen is planning some significant experiments, and even if the first ones fail, the results should tell us something important.”
Wurden acknowledges those problems and brings up another for good measure. “How do you control millions of amps of current at thousands of volts?” he asks. “The switches we use are fancy things that work under high voltage. We can switch high currents maybe 20 times a day.” But a working fusion reactor based on Shiva Star would need to handle such currents once every 10 seconds. He is on a roll now, plotting the path that could finally bring fusion energy to your household electrical outlet: “Maybe years from now, some of these things that are difficult to do today will be technologies we can handle. We’re at the Wright brothers stage now. If someone had given the Wright brothers the plans for a 747 and told them to just build it, well, they wouldn’t know what a jet engine is, and certainly wouldn’t have the ability to make turbine blades or alloys.
“If someone tells you we’ll have fusion energy in three years, that is not going to happen. Even if you want to solve the energy problem in the next 30 years, fusion is not the answer, and I say that as a fusion scientist. If you want to solve it in the 50-to-100-year timescale—yeah, I think it is the answer. I like to ask other physicists, ‘How many miracles do you need for your concept to work?’ There isn’t a single concept that doesn’t need an engineering miracle or two or three. Not one. But if you can count the number of miracles on one hand, you might say your concept is viable—you only need one handful of miracles. That’s where fusion research is: How many miracles do you need?”
THE HIGH-STAKES FUSION PLAYERS
Fusion energy research is the ultimate high-risk, high-reward scientific endeavor. So who better to tackle the challenge than entrepreneurs? “ITER and NIF have a heck of a lot of money, but they also have incredibly complex technology,” says Doug Richardson, CEO of British Columbia–based General Fusion. “We looked at the endgame from the very beginning: Can you put this into a power plant easily?”
To that end, Richardson and his competitors are scheming up novel reactor designs. General Fusion’s magnetized target fusion reactor will incorporate a multipurpose liquid-metal lining to produce tritium, protect equipment from damage, and extract the heat that generates energy. The company hopes to achieve break-even by 2013. Two other companies, Energy Matter Conversion Corp. (EMC2) and Tri Alpha Energy, are developing reactors that use proton-boron fuel, which requires even higher temperatures than deuterium does but allows almost direct conversion of fusion into electricity, without boiling water to drive a generator.
Still, it’s not easy fiddling with million-degree plasmas on a tight budget. With the exception of Tri Alpha, which secured $40 million in private funding (some of it from Microsoft cofounder Paul Allen) three years ago, fusion has proved too risky for even the most daring venture capitalists. General Fusion limped through its first four years supported by a couple hundred thousand dollars from family and friends. “Skepticism and credibility are our top challenges by far,” Richardson says. Andrew Grant