How Is Electricity Produced From Fusion?

When it comes to producing electricity, we know that humans use different fuels for its generation. We burn fossil fuels, utilize nuclear fission power and have renewable sources of energy, like solar power. However, all these sources of energy have a catch. Fossil fuels produce harmful byproducts, nuclear fuel produces harmful nuclear waste, and there simply aren’t enough batteries to go around to capture the full capacity of solar energy. However, what if we had a way to harness an immense amount of energy from a viable fuel with virtually no harmful byproducts? Well, we need to look no further for that answer than up to the heavens!

Inspiration for Fusion

sun

The inspiration for this breakthrough in energy generation comes from none other than our own Sun. As of today, the Sun (or any star, for that matter) is one of the best fusion reactors you could ever imagine. It has been producing an immense amount of heat and energy for billions of years (4.603 billion to be exact!) and does this through the efficient process of nuclear fusion. So, what exactly is fusion?

The process of nuclear fusion occurs when a single proton (which is a hydrogen atom without an electron) fuses with another proton to form helium. This transformation releases an extreme amount of heat and light energy. This process occurs in the core of the sun, and this constant combination and transformation of atoms is what powers our closest and favorite star. After the combination of the two protons, they might break apart again, but sometimes, one of the protons might change into a neutron due to weak nuclear forces. The resulting proton-neutron pair is sometimes referred to as deuterium.

potronNow, imagine that a third proton then collides with the deuterium. This collision results in the formation of a helium-3 nucleus and a gamma ray. These gamma rays work their way out from the core of the Sun and are released as sunlight!

Current Technology for Fusion

It would be amazing if we could trap a star in our backyard and harness its energy, but doing that is even theoretically impossible. Yet what if we had another way of looking at the problem? From our sun, we have learned that nuclear fusion occurs when the atoms receive sufficient energy to move at high speeds and bond together, colliding into one another and in the process giving out a lot of heat and light energy. We don’t necessarily need to bottle up a star for that to occur, but scientists have come up with two other unique methods:

  1. Inertial Confinement Fusion
  2. Magnetic Confinement Fusion

Inertial Confinement Fusion is also popularly known as fusion burn. For fusion burn to occur, a special fuel consisting of hydrogen isotopes of deuterium and tritium must ignite. The primary goal is to achieve fusion ignition, in which the energy generated from the fuel is greater than the X-ray radiation cost and electron conduction, which cool the process by making the fuel implode within itself.

This type of fusion has been achieved in the National Ignition Facility in Livermore, California. The NIF is the world’s largest and highest energy laser on the planet. As shown above, the NIF directs around 192 lasers into a gold cylinder called a hohlraum, which is about the size of a dime. A tiny capsule within the hohlraum contains atoms of deuterium (hydrogen with one neutron) and tritium (hydrogen with two neutrons) that fuel the ignition process. The design of the NIF is such that it can reach temperatures in the tens of millions of degrees – exponentially hotter than the earth’s atmosphere. These conditions replicated by the NIF can only be found in the cores of stars and planets.

Magnetic Confinement Fusion primarily functions with a magnetic confinement device. The way it does this is by using a powerful magnetic field to confine hot plasma in the shape of a torus. The device has an interesting name – the tokamak. There have been other attempts to achieve magnetic field containment, but the tokamak has been the most successful design to date. The positive and negative ions separate in the plasma of the tokamak when temperatures become extremely high. To prevent the plasma from cooling down, it must be contained within the central region of the tokamak. If it is not contained within the central region of the torus, it will spread out and rapidly cool down. The tokamak exploits the fact that charged particles in a magnetic field experience a Lorentz force and follow helical paths along the solenoidal shape.  The heat produced by the tokamak can be used for heating water into steam. This can then be run through a turbine in order to generate electricity.

tokamak

(Photo Credit : Mike Garrett/Wikimedia Commons)

Why isn’t fusion here already?

Now, although these are viable options for making electricity, nuclear fusion is still considered a far-fetched dream. There are two reasons why these wonderful and ideal missions are not connected and powering our cities already.

The first reason is the cost. The overall cost it takes to build these reactors runs into the multi-billion-dollar arena. Unlike its brother, the nuclear fission reactor (which is still expensive, but nothing compared to a fusion reactor), it is much harder to set up. Not only is money a primary need in this endeavor, but the bureaucratic system also gets in the way. The current bureaucratic system is slow and draconian in its ways, so much so that the cost to set up these plants keeps increasing with time.

However, the main factor that impeded the growth of the fusion boom (no pun intended) is based on a parameter known as the Q-factor. The Q-factor compares the energy output a reactor can give to the energy output needed to run the reactor. To date, only the tokamak design promises to provide a Q-factor greater than 1, which would make it a wise and sensible investment, both monetarily and in terms of energy production.

Only time will tell whether fusion energy will remain a promising idea that never really got to see the light of day or become a viable source of energy that changes the world as we know it!

References:

  1. Energy Education
  2. Inertial Confinement
  3. Magnetic Confinement
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About the Author:

Venkatesh is an Electrical and Electronics Engineer from SRM Institute of Science and Technology, India. He is deeply fascinated by Robotics and Artificial Intelligence. He is also a chess aficionado, He likes studying chess classics from the 1800 and 1900’s. He enjoys writing about science and technology as he finds the intricacies which come with each topic fascinating.

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