A new company in Seattle, CTFusion, was recently awarded a $3 million grant by the U.S. Department of Energy’s Advanced Research Projects Agency in Energy to help it develop the first commercial nuclear fusion reactor on this planet.
CTFusion seeks to provide flexible, carbon-free electricity using the same process that operates in stars.
Fusion is the process of building up simple atoms into larger more complex ones. It releases a lot of energy, and occurs every day in our Sun as well as almost every other star in the Universe. The trick for humans is to harness it on Earth for producing clean abundant energy.
Fusion is the opposite of fission, which is the process of breaking apart atoms. Both release energy under the right conditions. For fission, the bigger the atom, the more energy is released. For fusion, the opposite is true - the smaller the atoms used, the more energy that is released.
For this reason, most efforts towards fusion concentrate on hydrogen fusion, the smallest of atoms, to release the most energy. One of the challenges of fusion is the temperature required to produce significant amounts of power from an ionized gas (plasma).
CTFusion is using a novel approach to deuterium-tritium (DT) magnetic fusion energy by employing a compact toroid configuration called a spheromak (see figure below). This is maintained with the company’s plasma current sustainment technology imposed-dynamo current drive (IDCD) in a donut-shaped toroid.
The goal is to provide a commercially viable, grid deployable power plant design, given sufficient funding, by the 2030s.
Depending on the type of fusion, the temperatures are in the millions of degrees. For the DT fusion in CTFusion’s spheromak, plasma temperatures in the core have to exceed about 150 million degrees.
Think of the Sun.
These high-temperatures are largely a non-negotiable requirement for fusion because at lower temperatures, no matter how much fuel you put into the reactor, the amount of fusion power produced will be vanishingly small simply because fusion reactions are not likely to occur at lower temperatures.
There is a lot of misunderstanding about the set-up of fusion reactors, particularly CTFusion’s HIT-SI. One might think that the million-degree core would be a real hazard if something went wrong. But even at a million degrees, the material in the core doesn’t even have the mass of a dollar bill, so there is no danger from this temperature even if something does go wrong.
And unlike fission reactors, there is no decay heat or hot fuel since there is little radioactivity in the fuel. There is no solid fuel or core to melt down. It’s just hydrogen gas.
So how does CTFusion accomplish these high temperatures? As Derek Sutherland, CEO at CTFusion, puts it, “Assume that you have a cup of coffee on your desk you would like to maintain at 150° F. If left on its own, the coffee would begin to cool, and continue doing so until it reaches room temperature. The amount of time required for it to cool will depend on how quickly the heat leaks out of the cup into the ambient environment.”
You can slow that down by using a thermos or cup holder, but the coffee will eventually cool to room temperature unless we supply energy to the system to keep its temperature at 150° F.
“A solution for doing so, which also satisfies the everlasting need for caffeine during rainy days in Seattle, is to drink some of your coffee that has cooled slightly below 150° F, and then fill your cup back up with coffee that is 200° F. With a balance between energy input and output, the coffee temperature can be held nearly constant indefinitely.”
This thought experiment illustrates the first law of thermodynamics, otherwise known as conservation of energy. The coffee is the fusion plasma. The cup is magnetic containment from CTFusion’s spheromak. The hotter coffee poured into cup is charged helium nuclei and heat from resistive heating by electrical currents flowing in the fusion plasma.
All of these energy sources must balance the energy losses from the system to maintain the desired temperatures for fusion to occur and be maintained.
Difficult but doable.
To achieve conditions with high enough temperatures and densities for fusion, the plasma needs to be confined. Magnetic confinement keeps plasmas away from material walls because charged particles (electrons and ions) tend to follow magnetic field lines. But there are many ways to get there.
Inertial confinement fusion aims to compress the plasma, heating them to conditions where fusion reactions are more likely. Specific approaches include laser fusion, beam fusion, fast ignition, and magnetized target fusion.
Magnetic confinement fusion aims to contain a hot plasma in a device with immensely strong magnetic fields. Specific approaches include the spheromak, tokamak, stellarator, and reversed field pinch.
Each method has their hurdles to be overcome before they go commercial, but CTFusion’s spheromak is very compact and likely to succeed within the next decade.
CTFusion is one of 16 members of the Fusion Industry Association. It’s Executive Director, Andrew Holland notes that, “It is heartening to see that ARPA-E continues to support and encourage the good work of the fusion community. It’s an exciting time in the private fusion community, with over $1 billion in direct investment. We’re looking forward to great things from CTFusion.”
CTFusion is a spin-off company from the University of Washington in Seattle, that builds on almost 30 years of DOE, NSF and ARPA-E funded research and development carried out by the University of Washington’s HIT-SI laboratory, led by Professor Tom Jarboe. Founded in 2015, CTFusion is a member of the American Fusion Project run by the American Security Project.
Billionaires from Jeff Bezos, Bill Gates, Peter Thiel, and Richard Branson to the late Paul Allen, are investing bigtime in fusion research, seeing it as the ultimate power source for the future, whether on Earth or off.
New nuclear designs are ideal for any future that wants to reign in emissions, as all climate scientists have urged - and dozens of start-up energy companies have taking on the challenge.
In fact, the Pacific Northwest seems to be a magnet for innovative as well as traditional nuclear power. Bill Gates’ nuclear company, TerraPower, is only an hour drive from CTFusion and UW. As is Helion and AGNI, two other fusion companies. General Fusion, based in British Columbia, is only a few hours away.
NuScale Power in Corvallis, Oregon is on track to build the first small modular nuclear reactor in America faster than expected, within a few years.
So fusion would fit is perfectly to this nuclear landscape. And it could happen in as little as 10 years.
