A viable nuclear fusion reactor – one that emits more energy than it consumes – could be here soon by 2025.
That’s the acquisition of seven new studies, published on September 29 at Journal of Plasma Physics.
If a fusion reaction reaches that milestone, it could pave the way for a massive generation of clean energy.
During fusion, the atomic nuclei are forced together to form heavier ones atomo. When the volume of the resulting atoms is less than the volume of atoms created in their creation, the excess mass is converted into energy, releasing an extraordinary amount of light and heat. The fusion combines the sun and the stars, as powerful gravity in their hearts fuse hydrogen make helium.
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But an enormous amount of energy is needed to force the atoms together, occurring at temperatures of at least 180 million degrees Fahrenheit (100 million degrees Celsius). However, such reactions can generate more energy than they need. At the same time, the fusion does not produce greenhouse gases such as carbon dioxide, which drives global warming, nor does it produce other pollutants. And the fuel for the fusion – like the element hydrogen – is enough to Earth to meet all of mankind’s energy needs over millions of years.
“Almost all of us came to this research because we were trying to solve a really serious global problem,” said study author Martin Greenwald, a plasma physicist at MIT and one of the leading scientists who generates a new reactor. “We want to have an impact on society. We need a solution for global warming – otherwise, civilization is in trouble. It looks like it can help fix that.”
Most experimental fusion reactors use a Russian donut design called tokamak. These designs use strong magnetic fields to enclose a cloud of plasma, or ionized gas, at extreme temperatures, high enough for the atoms to come together. The new experimental device, called the SPARC reactor (Fastest / Smallest Robust Compact Robust Compact), was developed by MIT scientists and a spinoff company, Commonwealth Fusion Systems.
If this succeeds, the SPARC will be the first device to achieve a “burning plasma,” where heat from all fusion reactions maintains fusion without having to pump over excess energy. But no one has yet used the energy of burning plasma in a controlled reaction here on Earth, and more research is needed before SPARC can do so. The SPARC project, launched in 2018, is scheduled to begin construction in June, with the start of the reactor operation in 2025. It is faster than the largest fusion power project in the world, known as International Thermonuclear Experimental Reactor (ITER), which was conceived in 1985 but not launched until 2007; and although construction began in 2013, the project is not expected to produce a fusion reaction until 2035.
One advantage that SPARC can have over ITER is that SPARC magnets are designed to enclose its plasma. SPARC uses so-called high-temperature superconducting magnets that have become commercially available over the past three to five years, long after ITER was first designed. New magnets can produce stronger magnetic fields than ITER – a maximum of 21 teslas, compared to a maximum of 12 teslas of ITER. (In comparison, the Earth’s magnetic field reaches a power range from 30 million to 60 million of a tesla.)
These powerful magnets suggest the SPARC core can be approximately three times smaller in diameter, and 60 to 70 times smaller in volume than the heart of the ITER, which is adjusted 6 meters wide. “The dramatic reduction in size is accompanied by weight reduction and cost,” Greenwald, told LiveScience. “That’s really a game-changer.”
In seven new studies, researchers outline calculations and supercomputer simulations based on SPARC design. It is expected that SPARC will generate at least twice as much 10 times as much energy as pumped in, the studies found.
The heat from a fusion reactor will generate steam. This steam will drive a turbine and power generator, in the same way that most electricity is produced during this time.
“Fusion power plants can be one-on-one replacement of fossil fuel plants, and you don’t have to rearrange electrical grids for them,” Greenwald said. In contrast, renewable energy sources such as solar and wind “are not well received by the current design of electric grids.”
Researchers later hope that SPARC-inspired fusion power plants will generate between 250 and 1,000 megawatts of electricity. “In the current U.S. power market, power plants typically generate between 100 and 500 megawatts,” Greenwald said.
SPARC will only produce heat, not electricity. Once the researchers have developed and tested SPARC, they plan to build the ARC (Affordable Robust Compact) reactor, which will generate electricity from that heat by 2035.
“That was very ambitious, but that was the target we were working on,” Greenwald said. “I think this is really true.”
Originally published in Live Science.