Fusion energy is what powers the Sun and all the stars in the universe. Reproducing it on Earth, even on a small scale, would mean a clean, cheap, inexhaustible source of power. Here’s a look at the promise and challenges of fusion energy, together with some of the projects hoping to make the dream a reality.
Fission vs Fusion
A neutron is accelerated and strikes the target nucleus, usually Uranium-235. This splits the target nucleus and breaks it down into smaller isotopes, releasing an enormous amount of energy. Atomic bombs operate on this principle, and all of the world’s 440 nuclear power plants are based on fission.
Isotopes of hydrogen, typically tritium and deuterium, unite under conditions of extreme pressure and temperature to produce a neutron and a helium isotope. This liberates huge quantities of energy, much great than that produced from fission. Hydrogen bombs – 3,000 times more powerful than atomic bombs – rely on fusion reactions.
Why Fusion Energy?
- The primary fuel source for fusion is deuterium, which can be easily extracted from water.
- Deuterium-tritium fuel can produce 10 million times more energy than the equivalent amount of fossil fuel.
- Fusion provides a long-term energy supply that emits no greenhouse gases (the only waste product is helium).
- Unlike solar and wind power, fusion is not dependent on the weather, allowing for uninterrupted delivery of power.
- Fusion could provide consistent power in interstellar space, where solar energy is not readily available.
How it’s Generated?
Heat – Fusion fuel must be heated to 100,000,000C (180,000,000F).
Compress – It must be dense enough and confined long enough for nuclei to fuse.
Ignite – “Ignition” happens when enough fusion reactions take place to create a self-sustaining process.
Enjoy – Once ignition is achieved, the net energy yield is four times that of nuclear fission.
Bringing It To Life
Scientists have devised three approaches to harness fusion energy.
This method involves confining and controlling plasma with magnetic fields. The most effective magnetic confinement system is a toroidal, doughnut-shaped configuration, in which the magnetic field is curved around to form a closed loop. The most promising of the designs is the tokamak.
Laser beams are focused onto a pallet of deuterium-tritium fuel, heating its outer layers and creating an implosion that compresses the inner layers. The fuel core is squeezed to fantastic densities, triggering fusion. This method, also known as “fast ignition,” is deemed more practical and is part of a newer line of research.
Fusion can be combined with fission to create a hybrid nuclear reactor, where the blanket surrounding the core is composed of fissile materials. The fusion reaction acts as a neutron source, with each neutron triggering a fission reaction in the surrounding blanket. This method can significantly multiply the energy yield of the fusion reaction.
The Challenges With Fusion
Creating The Conditions
The Sun’s extreme heat and gravitational pressure compress hydrogen nuclei into heavier elements, releasing energy. Man-made reactors can’t achieve these pressures but they compensate generating temperatures 10 times hotter than the Sun.
Containing The Reaction
Major advances in engineering are needed to develop materials capable of withstanding the assault of fusion byproducts. Fast-flying neutrons pummelling the reactor chamber wall can weaken structural integrity and fill it with radioactive dust.
The International Thermonuclear Experimental Reactor is a joint research project of the US, the EU, Japan, Russia, China, South Korea, and India. Now under construction in France, it will use the tokamak magnetic confinement system to produce 500 MW of fusion energy.
General Fusion is a private nuclear fusion development company that was founded in 2002 in British Columbia, Canada. Their proposed plant will consist of a 4-meter diameter reactor and will use a “magnetized target fusion” technique that will raise the density of the plasma and increase the temperature until a pulse is generated.
Tri Alpha Energy
Tri Alpha Energy was founded in 1988 and is based in Orange County, California. The company is developing a reactor with a “field-reversed configuration” design which uses magnetic confinement and heat to induce continuous fusion. This reactor design is much simpler than a tokamak, but far less developed.
This is all the things you need to know about fusion energy. Future of energy.