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Is Nuclear Fusion an Answer to Our Climate Crisis? by Holly Thompson

Harnessing the power of nuclear fusion is one of the biggest problems that scientists currently face, and with pressure from national and international governments to cut down carbon emissions this problem needs to be solved quicker than ever. Fusion is a great way of creating electricity and energy from a nearly infinite amount of source material - deuterium (essentially heavy hydrogen), which can be extracted from water - and emits no CO2 or greenhouse gases.

So, what exactly is fusion?

To put it simply, fusion is the process that is carried out in stars such as the Sun to create a nucleus from the collision of two or more smaller nuclei. Typically high energy hydrogen nuclei collide together to create helium and tritium (even heavier hydrogen) nuclei, and this needs very high temperatures and pressures to work to overcome the repulsion that happens between the positively charged nuclei.

A nuclear fusion power station would use these reactions in a controlled environment. The majority of the energy is released in the form of a neutron which is then ‘caught’ by a blanket of lithium that is wrapped around the core of the power station. The amount of neutrons produced can vary due to temperature, however on average around one billion neutrons are generated per second. This interaction produces tritium, which is put back into the reactor, and heats the blanket which is then cooled by a fluid which drives a turbine much like steam would within a fossil fuel station.

The struggle to harness this power on Earth has been going on since the 1940’s when we were first able to carry out these reactions, albeit lasting for only a few microseconds at most. It has been so difficult to utilise this as it is hard to create the temperatures and pressures within a laboratory as the temperatures needed to start fusion are approximately T〜15-100million °C, and the energies needed to maintain these temperatures takes more energy than is currently able to be generated.

As it is so difficult to carry out these reactions within a laboratory, nevermind in a controlled environment, scientists are slowly progressing and large labs have been and are being set up to develop the technology needed for this to become a viable energy production source for the masses. ITER in Southern France is a collaboration project between 30 different countries originally aiming to create plasma within the next 10 years [1], however due to technology having to be pushed to its limits and issues with funding and budgeting, it is looking unlikely that actual fusion will be able to work within this time period [2].

Within the UK, funding has been secured for the Culham Centre for Fusion Energy, near Oxford, to create a design of the nuclear fusion plant STEP within the next four years, and possibly build it, which has the opportunity to generate hundreds of megawatts of energy - the energy equivalent of boiling 50,000 kettles at the same time. This centre has ambitious goals and the money to put behind them - around £200-million to create working sustainable fusion power by the early 2040’s. They are hoping that this will be a massive step forward in harnessing nuclear power and will ensure that, as a country, this will be a contribution to reducing the amount of fossil fuels used. They are also hoping that, in the future, the price of the energy generated for consumers will be competitive within the market and will encourage more people to move to using this type of renewable energy.

However, when people hear the words ‘nuclear power’, they think of highly radioactive waste, nuclear weapons and disasters such as Chernobyl and Fukushima. In reality, nuclear fusion doesn’t create any radioactive waste or use highly radioactive material, such as Uranium-235 and Plutonium-239 due to using very light elements, such as Hydrogen, Helium and Lithium. Any products that are made are typically entered back into the system as deuterium or tritium or the materials are reused within 100 years of creation, which minimises the dangers of a catastrophe of a nuclear plant ‘meltdown’.

It will be interesting to see if over the next 20-30 years, and even further into the future, if we will finally be able to use nuclear fission as a viable and sustainable power source, and if the STEP project will be the first to do this.

References [1] - ITER, “What Will ITER Do?”, ITER, 2019. Accessed at: https://www.iter.org/sci/Goals 10/11/19

[2] - Matt McGrath, “Nuclear Fusion is ‘a question of when, not if’”, BBC News, 6/11/19. Accessed at https://www.bbc.co.uk/news/science-environment-50267017

Credits:

Created with an image by Daniele Levis Pelusi - "Abstract n.1"