Nuclear fusion is a scientific process by which the nuclei (centre made up of protons and neutrons) of two atoms gain a great amount of energy and collide to form one atom whose atomic value is equal to the sum of that of the two (or more) elements that produced it. This differs from nuclear fission-a famous process completed in nuclear power stations around the world today (and in nuclear bombs).
Nuclear fission
During nuclear fission it is helpful to imagine the nucleus of an atom as a droplet of water (a model first suggested by physicist George Gamow-although important to remember it is an analogy, not actually the case). Particles must be launched at the nucleus with enough energy not just to overcome the ‘Coulomb barrier’ (an energy barrier that any particle or atom must go beyond in order to reach a nucleus) but to go so far over that when they hit the nucleus our ‘water droplet’ spreads into a dumbbell shape. It then-if enough force has been applied-should split into two smaller droplets: releasing large amounts of energy and particles at the same time.
Nuclear power-plants will always use an unstable element (very often Uranium) so that the fission products (created during the reaction from a heavy element splitting into two lighter elements) are often also unstable. This means the products undergo radioactive decay and degrade into lighter elements (decay again, degrade, etc) spitting off high energy particles. This creates a chain reaction, whereby the high energy particles collide with Uranium nuclei and cause another fission reaction. This ultimately continues on self-sustaining for a while and just needs topping up with fuel (Uranium) occasionally.
So, fission sounds great right?
Well, it certainly does produce a lot of energy (about 1 million times that of other energy sources), however fusion produces many times that number. Fusion creates Helium during the process, a widely used, often hard to come by resource that could have other purposes if we mass-produced it through fusion. Fission, on the other hand, produces harmful radioactive waste that can’t be used for anything and must be locked up in special storage units that, at some point, are going to fill up. Fission power-plants must be fuelled by Uranium or Plutonium-dangerous radioactive chemicals that are extremely rare and must be industrially manufactured through complex reactions (contributing to the greenhouse-effect). Fusion can just be fuelled by Hydrogen-an extremely common (and easy to cleanly manufacture) element that fuels most stars around the universe already, because that’s all a fusion reactor really is! A man-made star. So how exactly does it work?
Nuclear fusion
Nuclear fusion is a rather different scientific reaction whereby two or more (usually Hydrogen) atoms collide with the right amount of force that they succeed the Coulomb barrier, however do not go with such energy so as to cause fission. They now fuse together (hence the name ‘fusion’). As stated above: they form one atom whose atomic value is equal to the sum of that of the two (or more) elements that produced it. For example, two Hydrogen nuclei would fuse to form one Helium nucleus. This is exactly what happens in the sun.
The fusion process creates 10,000,000 times as much energy per Kilogram of fuel than any fossil fuel power station. So how does this happen? Well, the process of two nuclei fusing together-like during fission-causes high energy neutrons to be thrown off. In many fusion research units such as Culham Centre for Fusion Energy (CCFE) run by the United Kingdom Atomic Energy Authority (UKAEA) in a small village in Oxfordshire, England, they use a system where these particles then hit a denser material around the inside of the tokamak (a device which uses a powerful magnetic field to confine plasma) which slows it down. The slowing down of these particles creates large amounts of heat through friction, which is then converted to steam. This steam now drives turbines to bring energy to the grid.
In simpler terms
In simpler terms, nuclear fusion works by two atoms moving very fast due to large amounts of heat. These then collide, and if they did so with the right level of energy, they fuse together to form one different atom. This sends small parts shooting off, which crash into the walls of their container, and create heat by rubbing with their surroundings. This heat is converted to steam, which rises and spins turbines through an upward force. These turbines are connected to generators which bring energy from the spinning force.
The issue
This sounds great right? So, what’s the problem? Well, stars form when clouds of gas (usually Hydrogen) get extremely dense and cannot fight against its own gravity. It now collapses in on itself and becomes extremely dense. Particles start colliding, which creates heat. This heat gives more energy to other particles, which collide and create heat, etc. It’s very much self-sustaining until it runs out of Hydrogen. The trouble is that this process has to happen under particular circumstances, and it is often unlikely that those first particles will collide. Instead, research facilities such as CCFE must provide these particles with the energy themself. The sun’s core reaches temperatures of about 15 million °C, however “here on Earth, the most efficient reaction is that between two types of hydrogen – deuterium and tritium – which only fuse at temperatures over 100 million degrees Celsius.”-CCFE.
Laboratories around the world are working on ‘cold fusion’-the idea that fusion can be accomplished at room temperature-however, for now, it is not efficient enough to be rolled out.
#FundFusion
It is a global task that many of the top scientists are working on. The thing is, the UKAEA’s budget in 2018/19 £134m. It then increased to £172.3m in 2019/20, a growth of 29%, however do you think £170 million is enough to keep this mighty feat of engineering running for a whole year? It is not fair to only show this side of the story, as shortly after they committed to a legally binding contract to reach net-zero emissions by 2050, “the Government announced a £222m investment in UKAEA to deliver the concept design of an innovative, low-cost compact fusion reactor – the Spherical Tokamak for Energy Production (STEP). Alongside STEP, the Government also announced a £184m ‘Fusion Foundations’ investment to deliver the foundations necessary for a thriving fusion sector” -(UKAEA annual report and accounts 2019/20).
This is why we are working on starting up a petition* calling for the Government to signficantly increase the UKAEA's budget. So what do you say? Will you help us #FundFusion
*Updates about this petition will arrive in due time
For more information: thegreenfrogforum@gmail.com
