Nuclear Fusion: Unlocking the Ultimate Energy Source
Without nuclear fusion life on Earth would not exist.
The light rays from the sun that sustain life and the warmth of the sun that you feel on a sunny day is the result of fusion reactions at the core of the sun. This is the most powerful source of energy in the known universe. Scientists are working hard to re-create the nuclear fusion process here on Earth to power the future in a clean and unlimited way, as we face an impending energy and climate crisis.
What is nuclear energy and how does it power the sun? Let’s get back to the basics: everything is made up of atoms. Atoms are very small particles and at the centre of an atom is the nucleus. It has protons and neutrons in it, and moving around the nucleus are electrons. The number of protons tells us what kind of atom it is. For example, Hydrogen is a gas and every atom of hydrogen has one proton. There is energy stored in the nucleus of an atom, that is the reason it is called nuclear energy. It holds the atom together and to use this energy it needs to be set free.
There are two different and opposing ways to free the energy in atoms. FISSION vs. FUSION Basically, fission splits the atom into two or more smaller atoms, whereas fusion brings two atoms to become one. It fuses them. The nuclear power plants that we currently generate electricity from today are powered by fission. It is also the process that is used in atomic bombs. Fission occurs when atoms of uranium are split into smaller atoms which release energy in the form of heat and radioactive particles.
What is nuclear fusion and how does it power the sun? Nuclear fusion, the stuff that stars are made of is our best hope for unlimited, clean energy on planet Earth. Like the name implies fusion combines nuclei together. The core of the sun’s temperature and pressure from gravity is so high that nuclei and atoms come closer and closer together, eventually fusing, making one large nucleus. Fusing small atoms (like hydrogen fusing into helium) releases a tremendous amount of energy in the form of heat and light. You just have to look up at a star lit sky to see the immense power behind nuclear fusion that is powering stars galaxies away.
Want to read this story later? Save it in Journal.
What role does Albert Einstein’s theory of special relativity play in nuclear fusion? Atoms never rest: the hotter they are, the faster they move. In the sun’s core, where temperatures reach 15 million °C, hydrogen atoms are always moving. As they collide at very high speeds, the natural repulsion that exists between the positive charges of their nuclei is overcome and the atoms fuse. The fusion of lightweight/little hydrogen atoms produces a heavier element, helium.
The mass of the resulting helium atom is not the exact sum of the initial atoms. Some mass has been lost, while large amounts of energy have been gained. This is what Albert Einstein’s famous formula E=mc² describes: the tiny bit of lost mass (m), multiplied by the square of the speed of light (c²), results in a very large figure (E), which is the amount of energy created by a fusion reaction. Put simply, mass and energy are the same physical entity and can be changed into each other.
Diving deeper into the physics of nuclear fusion — warning nerd alert! Every second, our sun converts 600 million tonnes of hydrogen into helium (releasing a gigantic amount of energy). Without the benefit of the same gravitational forces at work, achieving nuclear fusion on Earth has required a different approach.
The most productive fusion reaction in a laboratory environment is between two hydrogen (H) isotopes deuterium (D) and tritium (T). The DT fusion reaction produces the highest energy gain at the ‘lowest’ temperatures but still requires the extremes of both high temperature and intense pressure, similar to the conditions of the sun.
Nuclear fusion can be created using hydrogen (H) isotopes — chemical cousins of hydrogen, like deuterium (D) — that can be extracted from seawater. The good news is, we have an abundance of seawater!
On Earth, we have a lot less gravity, so we need much higher temperatures for nuclear fusion to occur. “The first step is to heat a gas and turn it into a plasma”, says Binderbauer, CEO of TAE Technologies. “That happens through adding more energy, so at some point the ions and electrons that make up the atoms fall apart into a soup of charges,” he says. “That’s the state that actually most of the universe is in — what we call a plasma.”
What are the advantages of fusion?
- An unlimited amount of energy: Joining atoms in a controlled way releases nearly four million times more energy than a chemical reaction such as the burning of coal, oil or gas and four times as much as nuclear fission reactions (at equal mass).
- No CO2: Fusion doesn’t emit harmful greenhouse gases like carbon dioxide into the atmosphere. Its by-product is helium, a non toxic gas.
- No long lived radioactive waste: Nuclear fusion reactors do not produce long-lived nuclear or radioactive waste (unlike fission).
- Limited risk of arms proliferation: Fusion does not use fissile materials like uranium and plutonium used in fission. There are no enriched materials in a fusion reactor that could be exploited to make nuclear weapons like atomic bombs.
- No risk of a meltdown: A Fukushima or Chernobyl type nuclear disaster is not possible. It is difficult enough to reach and maintain the precise conditions necessary for fusion — if any disturbance occurs, the plasma cools within seconds and the reaction stops.
- Cost: Although most projects are currently over budget, the power output for the kind of fusion reactor that is anticipated for the second half of this century will be similar to that of a fission reactor, (in the range of 1 and 1.7 gigawatts). The average cost per kilowatt of electricity is also expected to be similar… slightly more expensive at the beginning, when the technology is new, and less expensive as economies of scale bring the costs down.
In most of the real world projects anticipated for nuclear fusion, the energy created in a reaction would heat water and run a traditional steam turbine generator. Plants could be safely and conveniently located in cities and other areas where power is needed.
“Fusion would have one other important benefit over solar, wind, and other intermittent sources of renewable energy”, says Christofer Mowry, CEO of General Fusion Inc., based in Vancouver, Canada: “It’s ‘dispatchable’ power.” …by dispatchable, Christopher means it’s power on demand, whenever the user wants it.
What are the technical barriers we need to overcome in order to make nuclear fusion successful? There is an old adage with scientists working in this space that a real world nuclear fusion application is always 30 years away... Scientists have been working for decades to develop a nuclear fusion reactor that could be used in a power station to generate power. The biggest obstacle is that fusion requires a very large amount of energy input to get it going. It requires production and confinement of a hot gas — a plasma. The temperature has to exceed 15 million °C in order to strip the electrons away from the nucleus before fusion can even start! Also, the engineering challenges for creating nuclear fusion are enormous.
The Q coefficient is the amount of energy produced in a nuclear fusion reactor to the amount of energy it requires to keep plasma in a steady state. When Q>1, now we’re talking. Currently it’s about 0.67. The ITER hopes to get a Q (fusion energy gain factor) of 10.
The technical barriers are big, but scientists and engineers are working on them.
Which companies are working on developing this technology? There are several (about 2 dozen) private companies working on commercializing nuclear fusion around the world. Here are a few of the more established companies in this space: General Fusion, Vancouver, Canada | Commonwealth Fusion Systems, Cambridge, USA | TAE Technologies Inc., Foothill Ranch, USA.
One exciting international project that stands out is the largest nuclear fusion reactor that is being built in the south of France, called ITER with 35 countries collaborating on it since 2010. ITER is short for International Thermonuclear Experimental Reactor. When ITER achieves its first plasma, which is predicted for 2025, it will have hit a fusion milestone: to produce more energy than it consumes!
How close are we to harnessing nuclear fusion in real world applications? It is only a matter of time before fusion plants start making some of our daily electricity, but can we develop them fast enough before Earth’s energy crisis and climate change really hit home?
Fusion will have an important place in the future energy mix. “The statistics will tell you in the next 25 years we’re going to double the amount of electrical demand and consumption,” Binderbauer CEO of TAE Technologies says. Reducing our reliance on fossil fuels will be critical.
The effort to harness fusion has been both inspiring and frustrating. The finish line may still be years (decades) away, but breakthroughs along the way have kept attracting scientists and large scale investors into this emerging technology that has the potential to change the way we power the world.
“I think everybody realizes that it would be desirable to have fusion as fast as possible,” says Steven Cowley, CEO of the UKAEA and head of the Culham Centre for Fusion Energy (CCFE).
We are well on our way to creating a machine that copies what happens inside the sun here on Earth, in a much smaller and controlled way. We have the potential to produce huge amounts of heat energy, which we could use to drive steam turbines and generators to produce electricity to help power the world. There would be no pollution, no carbon dioxide, and no deadly nuclear waste. We would have simple, clean, safe, power accessible to all nations. Let’s keep the dream alive!
Recommended video for visual learners:
📝 Save this story in Journal.
