In the first weeks of November, the world came together for the 26th United Nations Climate Change Conference, an event researchers across the globe are calling ‘the world’s best last chance to get runaway climate change under control’. During this two-week conference, one of the aims was to put forward proposals to ‘secure global net zero by mid-century and keep 1.5 degrees within reach’, which will involve phasing out coal use around the world and putting more resources into sustainable energy methods. One such method that is being touted as a groundbreaking solution is nuclear fusion. THINK magazine sat down with Prof. Ing. Pierluigi Mollicone and Prof. Ing. Martin Muscat, associate professors at the Department of Mechanical Engineering at the University of Malta, to learn more about what nuclear fusion is all about.
Fossil fuels and Renewable Energy
What do we mean when we talk about fossil fuels and renewable energy? Fossil fuels are fuels formed from geological processes acting on dead and decaying organic matter from many millions of years ago. These fuels occur in the form of coal, oil, and natural gas and are extracted all over the world from the Earth’s crust. Fossil fuels have proven very popular since their pivotal role in the industrial revolution and have led to the creation of the world we live in today. They are relatively inexpensive to extract and easy to contain and transport across the globe. However, as we have seen over time, they have a devastating effect on our environment, releasing large amounts of carbon dioxide, the major culprit of the greenhouse effect and the warming of our planet. Burning these fuels has also led to air quality depletion that has impacted our health.
Fossil fuels are a finite resource, unlike renewable energy sources, which are sustainable and can be replenished. Common renewable energy sources include solar, wind, hydro, tidal, geothermal, and biomass. As you can imagine, the major positive of renewable energy sources is the lack of pollutants; however, these sources are sometimes intermittent and can be quite dependent on environmental conditions. According to the Global Energy Review in 2021 by the International Energy Agency, ‘the share of renewables in electricity generation is projected to increase to almost 30% in 2021, their highest share since the beginning of the Industrial Revolution and up from less than 27% in 2019.’ But where does nuclear energy fit in with all of this?
Nuclear Energy – Fusion and Fission
Nuclear energy generation involves altering the way atoms are structured; however, there are two types of energy generation, fusion and fission. Both create large amounts of energy, but there are some major differences between the two. As Mollicone explains, ‘either you split the atom, which is called fission, or you join the atom, which is fusion.’ Fission reactions release large amounts of energy via the action of splitting atoms into smaller atoms, using a large, unstable isotope, such as uranium, as fuel. Particles are fired at the fuel, which splits it down into two smaller isotopes, releasing a large amount of energy and more particles that lead to further splitting, creating a chain reaction.
Fusion, on the other hand, involves combining two atoms to generate energy. It’s the same mechanism that is currently happening in our Sun, explains Mollicone, producing the light and warmth we feel all the way here on Earth. In the Sun, due to the extreme temperatures and gravitational forces, hydrogen atoms travel at rapid speeds and collide with each other. In normal circumstances, these atoms would repel each other, but in these extreme conditions, they fuse together, producing a helium atom. The fuels used for fusion reactions in man-made plants are currently two isotopes of hydrogen: deuterium, and tritium. Due to both fission and fusion reactions requiring fuels that are finite, they cannot be regarded as renewable energy sources.
Understanding how these reactions can produce energy falls at the feet of Einstein’s famous equation describing mass-energy equivalence, which is most easily recognised in its written form, E=mc2. The difference in mass between the original atoms and the products, the ‘m’ in the equation, is multiplied by the speed of light (the ‘c’) squared, resulting in a large amount of energy being released. Hence the viability of using this for power.
The fear of nuclear fallout has left many people wary of nuclear power. However, while both fusion and fission harness the power of the atom, their risks are quite different.
As Mollicone describes, ‘there are two main problems with fission reactions; you get a lot of radioactive waste, which lasts for many years.’ The waste that is produced has to be stored for around 1000 to 10,000 years, while ‘the radioactivity of high-level waste decays to that of the originally mined ore’ (World Nuclear Association, 2021). Mollicone continues, explaining the second problem, which is that fission reactions ‘are not stable’. Muscat adds, ‘what happens is, if the cooling system breaks down and you cannot cool your nuclear reaction, then the reaction goes out of control, then you’ll get a huge explosion.’ Reactions like this have led to disasters such as those in Chernobyl and Fukushima, which have had devastating and lasting effects on the communities and environment.
Whereas with fusion reactions, there is very little long-lived radioactive waste. The half-life of the small amount of radioactive waste from fusion is about 12.5 years, and as Muscat describes, a fusion reactor can be stopped by ‘just stopping the injection of fuel, much like how without fuel, a diesel engine will stop functioning.’ This means that these dangerous explosions don’t occur.
Fusion in Europe
Mollicone thinks ‘the answer will not be to rely on a single source’, but ‘that the answer is a mix of energy solutions to have a sustainable future energy supply.’ Many countries around the world are hoping that fusion will prove to be a valuable addition to existing renewable sources. Europe is making strides towards achieving a viable reactor with projects like ITER and DEMO enabled by the EUROfusion consortium. The latter is a project that Mollicone and Muscat are working on in collaboration with the Malta Council for Science and Technology via the ENDURE programme, helping to design components for a fusion reactor that aims to produce more energy than it requires to run.
Check out THINK’s next upcoming article about the EUROfusion Project, where we will be hearing more from Mollicone and Muscat about their work and how to design a working fusion reactor!