The Orkney International Science Festival
100 MILLION DEGREES AND RISING, Phoenix Cinema, Pickaquoy, Kirkwall, September 8th
By Eamonn Keyes
Dr Melanie Windridge, the speaker at this event, is a plasma physicist as well as being the founder and CEO of Fusion energy Insights, which keeps people up to date with developments in the growing fusion industry.
In addition, she is a very active individual, having climbed Everest in 2018.
This talk was delivered with considerable authority given Dr Windridge’s background and gave a real insight into the development and possible future of fusion power.
Energy has become the driving force of our society, with the fuel needed becoming a vital strategic resource that can trigger wars and define the status of nations possessing it.
Energy security is now increasingly important for the development and growth of society.
The International Energy Agency defines energy security as the uninterrupted availability of energy sources at an affordable price. Energy security has many aspects: long-term energy security mainly deals with timely investments to supply energy in line with economic developments and environmental needs.
However, as time has gone on we have seen that the use of the commonest fuels has resulted in a rise in emissions, pollutants and atmospheric carbon and heat that cannot be sustained, and the search is on for a clean sustainable energy source for the future.
Initially, nuclear fission was thought to be the probable solution but has proved to be a dead end, producing radioactive contamination that will last for millennia, and with the environmental danger of meltdown a real issue.
The Holy Grail is now seen to be nuclear fusion.
Nuclear fission is about the splitting of heavy atoms, producing energy and neutrons which go on to strike other atoms in a chain reaction, leaving dangerous isotopes behind.
Nuclear fusion takes place when two low-mass isotopes, typically Tritium and Deuterium, isotopes of hydrogen, unite under conditions of extreme pressure and temperature to produce a neutron and a helium isotope. Along with this, an enormous amount of energy is released, which is several times the amount produced from fission, and without any real waste. It is extremely efficient and clean, being the mechanism that drives the Sun. There is no risk of meltdown as with fission and it uses much less radioactive material in the process.
Before the Industrial Revolution, the horse was the main means of power, and it was replaced by the chemical energy of steam, coal and eventually oil, multiplied by a factor of 1000. Nuclear fusion will boost this to a factor of more than one million.
I kilogram of fusion fuel produces the same energy as 10 million kilograms of coal, but with zero emissions being produced in the process.
The search for this seemingly perfect energy source has been hampered by the technical difficulties involved, as a fusion reaction can only take place in conditions of very high temperatures and enormous pressures with atoms moving at high speeds to being about the fusion, because of the repelling force between protons, similar to pressing two magnets together when they are repelling each other. They can come together if pushed hard enough. The conditions for this turn the material into highly charged plasma. Plasma is also seen glowing in neon tubes, lightning strikes and in the Aurorae.
The key problem in achieving thermonuclear fusion is how to confine this hot plasma. Due to the high temperature, the plasma cannot be in direct contact with any solid material, so it has to be located in a vacuum and contained.
Until recently the two methods used to try to confine plasma in fusion reactor research were by magnets and lasers, tasked to achieve ignition, the point at which a nuclear fusion reaction becomes self-sustaining. Artificial Intelligence in the form of machine learning and the latest superconductors are helping in this advanced programme.
The magnetic method, which has had 40 years research ploughed into it, is used in Tokamak reactors, such as the ITER reactor, where 18 huge magnets, the biggest in the world, are used to confine the plasma within a massive installation. This is the type of reactor being utilised in the UK’s fusion programme.
In the laser method, the National Ignition Facility (NIF) laser array in the USA uses 192 lasers focused to heat the surface of a pepperoni-sized pellet into a plasma, which explodes away from the surface. The rest of the pellet is driven inward on all sides, into a small volume of extremely high density. The surface explosion creates shock waves that travel inward. At the centre of the fuel, a small volume is further heated and compressed. When the temperature and density are high enough, fusion reactions occur.
The NIF reactor finally achieved ignition on December 6th 2022.
China’s Experimental Advanced Superconducting Tokamak (EAST), a nuclear fusion reactor research facility, sustained plasma at 70 million degrees Celsius for as long as 17 minutes, 36 seconds, achieving the new world record for sustained high temperatures (fusion energy however requires temperatures over 150 million °C).
On February 15th, 2023, the Wendelstein 7-X reactor in Germany reached a new milestone: Power plasma with gigajoule energy turnover generated for eight minutes.
In addition, South Korea’s Superconducting Tokamak Advanced Research centre (KSTAR) has reached an important milestone with its Tokamak reactor, holding a temperature above 100 million degrees Celsius for 30 seconds.
These advances have moved nuclear fusion from being a physics problem to being an engineering problem. However, there will need to be a huge investment to bring this into a useable form, with some suggesting a modern Manhattan Project is needed to bring this to fruition, as funding has just about kept the research alive.
In time it seems inevitable that nuclear fusion will become viable, producing huge amounts of clean energy without the emissions and waste that have taken us to the brink of climate catastrophe. However, the possibility of having something like Iron Man’s fusion reactor may not be available in your local shops this Christmas.
