Fission and fusion – two alternatives to fossil fuels
While the two might sound almost identical, fusion and fission offer two differing ways for us to harness energy from particles instead of hydrocarbons.
Energy can be derived from all kinds of places. We have drilled into the surface of the Earth to find coal, oil and gas, but these energy sources are finite. If we continue to use energy at the present rate of consumption, fossil fuels will be depleted by 2060, according to Octopus Energy.
In order to prevent global temperatures rising by no more than 2 degrees Celsius above pre-industrial levels by 2050, we need to change our ways. As much as 80 per cent of our coal, 50 per cent of our gas and 30 per cent of our oil reserves need to be deemed ‘unburnable’ in order to ensure such an outcome.
We don’t just have to burn coal, oil or gas to stay powered up. Some of the most incredible sources of energy come from atoms themselves. Fusion and fission are two ways of doing this, but which one is most suitable?
Fission blows atoms wide open
Nuclear fission, first discovered in 1938, means taking an unstable large atom and splitting it into two smaller atoms known as fission products, which are far more stable. The process of splitting atoms releases tremendous quantities of energy. The sting in the tale is that the energy produced is highly radioactive.
This release of radioactive energy is hot enough to evaporate water and power electric turbines, allowing nuclear fission plants to produce huge quantities of energy. It is estimated that nuclear fission represents 20 per cent of the UK’s energy mix, but half the UK’s nuclear capacity is due to be phased out by 2025.
One of the biggest criticisms of using fission to generate power is the fact that the process of fission always generates radioactive waste. Depending on the unstable element used in the fission process, radioactive waste can take thousands of years to decay.
Fission-based energy generation has led to a handful of incidents that became ingrained in the public’s consciousness, for fear of the lingering danger of nuclear fallout and radioactive contamination following both man-made and natural disasters involving fission plants. These include the Chernobyl incident in Ukraine in 1986, as well as the Fukushima disaster in Japan back in 2011.
The fate of fission power hangs in the balance in the UK. If the Government decides not to commission new plants from 2025 onwards, alternative sources of energy will be required, to avoid complete dependence on fossil fuels.
A fusion-led future could be cleaner
Rather than bombarding atoms in order to break them into smaller pieces and release energy, fusion is an entirely different way of generating energy. While it also uses atoms to harness power, fusion relies on combining two lighter elemental atoms to create a single heavier atom. One of the biggest benefits of adopting a fusion-led path is that the process produces no long-lived radioactive waste.
In effect, fusion generators would seek to emulate the process that powers our Sun. The Sun takes lighter hydrogen atoms in gaseous form, heating them to form a plasma – a superhot ionised gas. The plasma makes it easier to filter negatively-charged electrons from positively-charged ions and fuse them together to form the helium. The resulting reaction produces immense quantities of energy in the form of heat and light.
The only issue facing scientists is that it can be tricky to ensure that the ions and electrons can actually be fused without generating tremendous amounts of heat to make it happen. The Sun is able to achieve fusion due to its immense gravity. The particles have no option but to fuse in the Sun but on Earth, the particles need to be superheated to achieve this – this risks melting the vessel used to make the particles fuse.
Fortunately the MAST Upgrade experiment is the UK’s step towards creating a workable fusion energy source. It just got switched on, and its creators intend for it to use the power of magnetic fields to hold plasma in a vessel, allowing the ions and electrons to fuse without complications.
Let’s hope it’s the first step towards a new generation of fusion reactors.
Feature and JET photo credits : EUROFusion