Mateusz Szczerbiński 

As the world is turning more and more to eco-friendly solutions by introducing various energy policies, and our resources potentially only lasting for about 200 more years, scientists are trying to find new energy sources. Fossil fuels are currently the most commonly used energy source, but they are harmful for the environment, and the more ecological options such as solar panels and other renewable sources are not yet as efficient. That’s why it’s important that we focus on developing a long-term, eco-friendly and mostly powerful energy source. Even though nuclear fission is a promising option, it necessitates radioactive waste management, thermal pollution of water sources, and huge contamination in case of an accident. That’s where nuclear fusion appears. It shows huge potential in its efficiency and eco-friendliness. The problem? So far scientists aren’t able to contain it in order to actually produce energy.  

Nuclear fusion is a process in which two atomic nuclei, usually hydrogen isotopes deuterium and tritium, combine to form a heavier one, in this case helium-4. This reaction requires extreme amounts of heat reaching 150 million degrees in order to create plasma, high density allowing for a better chance of collisions and confinement time long enough for the fusion to generate more energy than it uses. The current technology is not able to guarantee these conditions, which is why so far scientists have not been able to harness the energy from nuclear fusion.  

In order to understand the conditions necessary for fusion to take places and the problems scientists face trying to create them, we need to take a deeper dive into how it works. Most importantly, when fusing, the nuclei need to cross the Coulomb barrier, which essentially is an electrostatic repulsion between two positively atomic nuclei preventing them from coming close enough to fuse. In order to phase through it, they need enormous amount of energy that can be calculated from the Coulomb Barrier Height formula: 𝑉𝑐 = 𝑒24×π×𝜀0×(𝑅1+𝑅2), where e – Elementary charge (1.602× 10−19), 𝜀0 =8.854×10−12 – permittivity of free space, 𝑅1,𝑅2- Separation distance  

The energy needed for a reaction of a single atom of deuterium and tritium is equal to no more than around 0.4 MeV. This is the maximum potential value necessary, but it is reduced by quantum tunnelling which happens in the real world. It allows us to carry out the reaction at a much lower temperature reducing it from 4 billion Kelvin to around 150 million, which cuts the needed energy to 0.013 MeV.  

In order to calculate the output energy form the reaction, we can use the Albert Einstein’s mass-energy equivalence energy formula:  

𝐸 = Δ𝑚× 𝑐2, 

where E – energy, Δ𝑚- the difference in mass, c – speed of light 3×108 

The missing mass, coming from the reactants, deuterium and tritium (8.3554×10−27𝑘𝑔) being heavier than the resultants helium and a free neutron (8.3233×10−27𝑘𝑔) by 0.0302×10−27 𝑘𝑔, is converted into energy. Substituting all of the values gives the energy output of around 17.5 MeV, which means that the energy received from the reaction is much greater than the energy necessary to carry it out, producing an efficiency of 135 000%.  

There is a number of problems the scientists are facing while trying to achieve nuclear fusion. Some of them concern the difficult nature of containment of the reaction. Due to the extreme temperatures needed for it to happen, plasma has to be kept in special vessels called Tokamaks which use electromagnetic fields to prevent it from touching the inside walls as it would simply evaporate them. Other problems have to do with creating the right conditions for the reaction. In order to fuse, the atoms need to be heated up to the desired temperature which is a complicated process. Some of the methods used are Ohmic Heating, Neutral Beam Injection or electromagnetic waves. Even when these conditions are met, it is still difficult to ensure all the atoms used are fused. Right now, scientists are able to achieve fusion of around 0.001% in a given reaction. It happens due to the fact that the collision of the atoms needs to happen head on.  

If we were able to innovate our technology to a point of being able to achieve the efficiency rate of the reaction at the level of even 10%, it would already make a powerful energy source, one much more efficient than other available sources. Not only would it be sustainable, but it would also produce no greenhouse gasses and no long-lived radioactive energy waste. It would prove to be a perfect energy source for the future. As all technology is getting more and more advanced, it is probably only a matter of time until a new one appears and allows us to ensure a cheap, efficient, and eco-friendly way of providing energy.  

Photo taken from: https://www.aveva.com/en/our-industrial-life/type/article/how-close-is-nuclear-fusion-power