Fuelling the Future: The Promise of Plasma Fusion
Our future climate stability dependent on moving away from oil and coal and closer to net-zero electricity production through a spectrum of alternative sources, Edinburgh Science director Simon Gage was joined by Doctor Fernanda Rimini of JET (Joint European Torus), Doctor Piergiorgio Sonato of ITER (International Thermonuclear Experimental Reactor) and Doctor Luca Antonelli of First Light Fusion for an event entitled Fuelling the Future to discuss the challenges of achieving and scaling sustainable plasma fusion reactors and the gradual progress towards this being a viable commercial energy source.
Where nuclear fission which splits heavy atoms such as uranium or plutonium and releases vast energy but also creates hazardous by-products, nuclear fusion is the process where energy is released by persuading some of the lightest elements to fuse together, akin to the process where hydrogen is converted to helium in the Sun and other stars.
Doctor Rimini said this had led to a common belief that they were “star makers,” but she explained this was not quite so, the key difference being that being unable to match the great pressure at the core of a star a fusion reactor instead compensated by running ten times hotter than the Sun, around 150 million degrees, but this of course is not a simple process.
“It’s very difficult to get it going and very difficult to keep it going,” she said, however this reticence of the fuel to cooperate is not without advantages with some of the inherent dangers of nuclear fission which discourage its widespread adoption never arising, fusion reactors having no weapons applications and not being susceptible to runaway chain reactions.
Doctor Rimini’s work involving the JET Tokamak, a fusion reactor which uses powerful magnetic fields to hold and shape the hot plasma which drives the reaction, running on deuterium which is found relatively abundantly and tritium which is produced within the power plant itself it is currently the most powerful in the world but within ten years she hopes that a new generation of experimental machines will be set to surpass that record, with a site in Nottinghamshire one of the proposed locations.
Introducing ITER as “the most advanced science diplomacy example in the world,” Doctor Sonato was proud of his association with researchers from many countries collaborating together on the goal of “generating sustainable energy for the planet,” seeing the project as representing “global involvement of all the countries in the world to solve a global issue.”
Doctor Antonelli taking a different approach, his work involves the alternative process of inertial confinement fusion where lasers focused on a single point collapse atoms together, the temperature not as high as a Tokamak but dependent on greater pressures. The current M3 machine functioning once a day, in order to be viable it needs to operate ten times a second, but the M4 is already proposed with Doctor Antonelli hoping to have a working prototype within the next decade and commercial power generation by the 2030s or 2040s.
Considering the technical challenges which must be overcome in the immediate future upon which all three speakers and their colleagues were focused, Doctor Sonato spoke of the need for efficient superconductors and materials of immense durability to withstand and last for decades within the extremes conditions of the generators, but Doctor Rimini was confident that while it would take time and hard work the diligent application of resources and intellect would bring the solutions to the current problems.
Doctor Antonelli explaining how the insights gained working with high pressure environments led to understandings which had applications in apparently unrelated fields such as cosmology and the physics of the interiors of gas giant planets, Doctor Rimini confirmed that without the toxic wastes generated or the need for the shielding which surrounds fusion reactors that there were companies advocating for fusion to power space travel or naval vessels, though she added that was not her particular field, though with a lower limit below which the reaction is not possible and an upper limit at which it becomes inefficient there is an optimum reactor size for the purpose it is needed for, allowing such adaptability.
Prompted by thoughts of space, Doctor Rimini spoke of the possibility of using helium-3 as a fuel source, unavailable on Earth but found on the Moon, a reaction which would require higher temperatures still but would yield greater energy, what she regarded as the “holy grail” of nuclear fusion, though Doctor Antonelli cautioned that for all the optimism on display and possibilities discussed a move to nuclear fusion alone was not going to stop dangerous climate change: “We have to solve that first.”
The Edinburgh Science Festival continues until Sunday 16th April
