Quirks & Quarks·Analysis

Could a Canadian company's new project finally make fusion power a reality?

Bob McDonald's blog: Vancouver-based General fusion uses a unique technology to duplicate the heart of a stars. It's one of several fusion projects underway around the world.

Bob McDonald's blog: Vancouver-based General Fusion uses a unique technology to duplicate the heart of a star

Illustration of General Fusion's Magnetized Target Fusion (MTF) technology. The blue plasma, centre, is surrounded by a liquid metal chamber which is in turn compressed by pistons. (General Fusion)

Vancouver-based fusion energy company General Fusion has entered an agreement with the United Kingdom Atomic Energy Authority to build a nuclear fusion demonstration plant to be operational in 2025. It will take a unique approach to generating clean energy.   

There is an industry joke that fusion energy has been 20 years away for 50 years. The quest to produce clean energy by duplicating the processes happening at the centre of the sun has been a difficult and expensive challenge.

It has yet to be accomplished on anything like a commercial scale. That is partly because on Earth the fusion process involves handling materials at extreme pressures and temperatures many times hotter than the surface of the sun.

The nuclear technology that has provided electricity for decades around the world relies on fission, which splits heavy atoms such as uranium into lighter elements, releasing energy. However, this produces hazardous and durable radioactive waste that must be stored, and more catastrophically has led to major accidents at Chernobyl and Fukushima.

Fusion is the opposite of fission. Lighter elements such as hydrogen are heated and compressed to fuse into heavier ones. This releases energy, but with a much smaller legacy of radioactive waste, and no risk of meltdown.

Stars are powered by nuclear fusion, but the extreme temperatures and pressures needed are difficult to produce on Earth. (NASA/SDO)

The world's largest fusion reactor experiment, ITER (Latin for "the way") is currently under construction in southern France. It's a massive international collaboration developing on fusion technology that's been been explored since it was invented in the Soviet Union in the 1950s. It involves a doughnut-shaped metallic chamber called a tokamak that is surrounded by incredibly powerful superconducting magnets. 

An electrically charged gas, or plasma, will be injected into the chamber where the magnets hold it, compressed and suspended, so it does not touch the walls and burn through them. The plasma will be heated to the unbelievable temperature of 150 million C, when fusion begins to take place.

And therein lies the problem. So far, experimental fusion reactors have required more energy to heat the plasma to start the fusion reaction than can be harvested from the reaction itself. Size is part of the problem. Demonstration reactors are small and meant to test equipment and materials, not produce power. ITER is supposed to be large enough to produce 10 times as much power as is required to heat up its plasma.

Inside the tokamak building of the International Thermonuclear Experimental Reactor (ITER) in Saint-Paul-les-Durance, southeastern France, on July 28, 2020. (CLEMENT MAHOUDEAU/AFP via Getty Images)

And that's the holy grail of fusion: to produce enough power that the nuclear fusion reaction can become self-sustaining.

General Fusion takes a completely different approach by using mechanical pressure to contain and heat the plasma, rather than gigantic electromagnets. A series of powerful pistons surround a container of liquid metal with the hydrogen plasma in the centre. The pistons mechanically squeeze the liquid on all sides at once, heating the fuel by compression the way fuel in a diesel engine is compressed and heated in a cylinder until it ignites. 

This technique, called magnetized target fusion, can theoretically reach the 150 million C mark in a small space. That heat is absorbed by the liquid metal and used to produce steam and run a turbine to generate electricity.

The General Fusion project in England will be a proof of concept to show how the technology works on a commercial scale. It is expected to be operational by 2025 at an estimated cost in the $400 million US range, which might seem like a lot, but is way below the 20 billion euro ITER Project, which is already years behind schedule and triple its original budget. 

A plasma contained by magnetic confinement. Magnetic confinement prevents the high-pressure, high-temperature plasma necessary for fusion from destroying its containment vessel. (U.S. Department of Energy)

Fusion energy promises to provide clean, 24/7 power that would be the baseline electrical supply to support the more variable sources of clean energy such as wind and solar. So far, fusion still remains a promise as it has for decades. 

But that promise might be closer than it's ever been before. ITER is nearing completion. Other fusion reactor designs are being developed. MIT is working on a smaller, more efficient tokamak reactor called SPARC. And there is another design called a stellarator that could require less input energy than a tokamak, that is being tested in the U.S., Germany and Japan.

But who knows — perhaps the Canadian approach will be the first to turn that long promise into a reality.

ABOUT THE AUTHOR

Bob McDonald is the host of CBC Radio's award-winning weekly science program, Quirks & Quarks. He is also a science commentator for CBC News Network and CBC-TV's The National. He has received 12 honorary degrees and is an Officer of the Order of Canada.

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