Viewpoint
Controlled fusion has the potential to be a long-term energy source. David Kingham explains the next steps
The world needs abundant, clean energy. Fusion – with no CO2 emissions, no risk of meltdown and no long-lived radioactive waste – is the obvious solution and has been for decades, but it is so hard to achieve. Controlled fusion is the ideal long-term energy source, complimentary to renewables. But why has it proven so difficult?
The challenge is that fusion only happens in stars, where the huge gravitational force creates pressures and temperatures so intense that usually repulsive particles will collide and fuse. On Earth we need to create similar conditions and hold a hot electrically charged plasma at high enough pressure for long enough for fusion reactions to occur. This is understandably tricky and the problem has occupied some of the world’s brightest minds for over half a century. Different approaches to fusion energy are being pursued, from cold fusion, which lacks evidence and may never work, to inertial fusion, which could work, to magnetic fusion, which does work.
Two recent papers from MIT and from a group in Durham and Culham in the UK add weight to magnetic fusion methods by throwing the spotlight on the use of high-temperature superconductors (HTS). Both focus on the same novel material – REBCO second- generation HTS tape – and, taken together, add confidence that the engineering of high field HTS magnets is feasible, resulting in more compact and commercially viable tokamak fusion power devices.
These papers reinforce the approach taken by Tokamak Energy, which has recently demonstrated a small tokamak with all its magnets made from REBCO HTS and been recognised as a Technology Pioneer of the World Economic Forum as a result of its progress and bold plans.
Magnetic fusion uses strong magnetic fields to pressurise and trap the hot plasma fuel. There are many configurations of magnets to achieve this, but the best performance has been achieved in ring-shaped tokamak devices, the simplest shape that has no open-ended magnetic field lines. The JET tokamak at Culham Laboratory achieved 16MW of fusion power in 1997 with 24MW of input power.
However, progress since then has slowed because the successor device, ITER, reached such gargantuan proportions that it has succumbed to numerous delays. In recent years efforts have focused on a smaller way to fusion. Can this most studied and top-performing device be reduced in scale?
Within the class of tokamaks there are two choices – the conventional doughnut shape such as JET or the apple-shaped spherical tokamak, described recently by Dan Clery in Science magazine as “the new kid on the block”. The spherical tokamak has two big advantages: being a squashed-up version of the tokamak it is inherently compact. Additionally, it uses the magnetic field more efficiently.
Its limitation has always been the tricky engineering due to lack of space in the centre for magnets and associated temperature controlling and protective elements. But the rapid development of HTS materials is overcoming this. Exceptionally high-field magnets can now be made that allow simpler solutions to the problems of cooling and protection, thanks to their ability to conduct high currents with zero resistance at temperatures well above absolute zero and in a strong magnetic field.
Earlier this year, Tokamak Energy scientists published two ground-breaking papers in Nuclear Fusion. One showed for the first time that it is feasible to build a low power tokamak with a high power gain. The second tackled one of the toughest engineering challenges of a compact spherical tokamak – the shielding of the centre – with HTS materials.
So instead of building ever larger tokamak devices, with huge costs and long timescales, we are now moving forward by increasing the magnetic field in more compact devices. This turns the pursuit of fusion energy from a big moonshot to a series of engineering challenges.
Currently, HTS technology has allowed Tokamak Energy to build and demonstrate a tokamak with all its magnets made from HTS, achieving that first challenge and moving us
on to the next: designing a compact tokamak to get to fusion temperatures. When we succeed with one challenge, we can raise the investment to tackle the next. Tokamak Energy is deliberately trying to tackle difficult engineering challenges as rapidly as possible, something HTS materials is helping us do.
Fusion energy projects and start-ups around the world are pursuing fusion in different ways. This concerted effort towards fusion is the best way to reduce greenhouse gas emissions and ensure the supply of safe, clean energy long into the future.
Dr David Kingham is chief executive of Tokamak Energy
If/when some group succeeds in taming fusion – who will own the technology? After 50+ years of work and untold billions spent, it seems unfair to make the technology public. Without mentioning specific countries, there are those that are “hostile” to our way of life. There are those that the West have given trillions for oil. Here we are in 2015 ordering nuclear reactors from China when we were way ahead of them at one time. If Culham were to succeed, who would have their fingers in the massive pie?
Fusion as an energy source is just smoke and mirrors we have been chasing that dream for over 50 years.
40-mumble years ago, I started work as a researcher on fusion. Back then we said that it would be 25 years before there was commercial fusion. Now the claim is more like 40 years. I leave it to others to produce an algorithm that links my life span to the timetable for fusion. Needless to say, I am not optimistic. But it is nice to see people like David trying to overtake the leviathans.
How long do we have to continue wasting trillions chasing phantom problems that have no solution? Forty years ago the specter of worldwide oil shortages had the alarmists in a tizzy to switch to vastly more expensive alternative energy sources to avoid the collapse of civilization after the mid 1990’s consumption of the last drop of oil in the world.
Of course, this never happened and by the 2000’s the world was awash in so much oil and gas that the alarmists had to change their tune and promote spending additional trillions to develop “Green Energy” alternatives to reduce the consumption of carbon based fuels.
Unfortunately, the Green Energy pipe dream can never come to fruition. Europe and the US can pave over every square centimeter of their land to construct wind, solar, and thermal energy generating plants and it still won’t come close to producing enough energy to replace the existing power generation sources.
Worse, even if Europe and the US bankrupt their economies producing energy that is too expensive for anyone to afford without massive reduction in living standards expansion of the Chinese, Indian, and Brazilian economies will replace every atom of carbon Europe and the US reduce with 20 atoms generated by their massive burning of coal and the increase in standard of living of their billions of people resulting in purchase of billions of cars and adopting high energy consuming western style lifestyles.
Short of declaring war on these emerging economies and forcing them back to pre-industrial levels there is nothing the West can do to stop them from flooding the world’s atmosphere with massive quantities of CO2. So, if the alarmists theory that man made CO2 production is causing global warming is true then we’d all better get used to living in the new world climate.
At the dawn of the 19th century most people in Europe and the US had never seen a car much less driven one. A decade later cars had largely replaced horses and two decades later it was rare to see a horse on the road. Humans used horses as the primary source of transportation for thousands of years yet when a better alternative was developed horses were eliminated virtually overnight.
The solution to global warming is not to bankrupt western economies subsidizing green energy that no one can afford to buy and that the Chinese, Indians, and Brazilians will never use. The solution is to develop energy alternatives that are better and more economical and that will displace current energy sources without government intervention.
Right now, fusion power holds the most promise of providing that paradigm changing technology. While skeptics complain that Fusion will not be commercially viable for 20 years they conveniently fail to mention that it will take much longer than 20 years to build enough windmills and solar plants to generate enough super expensive energy to replace the current carbon and fission based plants.
Once (comparably) “free” fusion power becomes viable it will replace most other energy alternatives virtually overnight. Chinese, Indian, and Brazilian coal and oil based power plants will be shuttered and the thousands of massively subsidized windmills dotting the European landscape will be abandoned and left for future generations to use to instruct their children on the folly of governments.
Yes it’s true: old Nuclear fission technology does not come off well by perpetuating a process that’s a legacy of world war & cold war where one purpose remains – weapons grade plutonium and the inherent risk for proliferation.
But here’s where Thorium MSR Nuclear technology stands above the rest to help make the difference and put the brakes on climate change. The Nuclear Industry needs a step change away from its lock-in to the past that perpetuates the flawed solid fuel based Nuclear fuel technologies … with it’s limited efficiency (0.5% of fuel used – and why so many see this as unreasonable due to the obvious wastes). Should we continue with such a contrived process to ensure safety for such a low yield burnup efficiency as a return on all the efforts?
At a time when climate change is very much on the agenda it’s almost as if simplifying the current ‘steam driven’ Nuclear Technology with its flawed solid fuel system and safety critical high pressure water systems should be higher up on the agenda. One of the main issues with solid fuel is when Xenon gas is produced as a fission by-product … this plays havoc with solid fuel – ‘poisoning’ the reaction process (this was overlooked and led to the disaster at Chernobyl). The Xenon out-gassing compromises the cooling efficiency to become the main reason for limiting the fuel life from stress fractures and potential effect on the Zirconium clad fuel rods. These so called ‘spent’ fuel rods then have to be replaced (if you can call 0.5% burnup ‘spent’) otherwise it may affect the fuel rod – being the first level of containment . Another major flaw is the tendency for Zirconium to draw oxygen away from surroundings when things get too hot … resulting in Hydrogen gas. Having to vent this (never a good idea with radioactive materials around!) to reduce the containment vessel pressure – led to an explosive atmosphere build up in the reactor halls with eventual explosions at each affected reactor in Fukushima.
This should be where the comparison to the slicker Molten Salt Reactor that allows 99.9%+ burnup while working at safer atmospheric pressure, as well as more thermally efficient operation (Brayton compatible), cannot melt down … it’s already in a fluid state … in a scram condition it can only become cool and end up as solid. Thorium needs fissile material to begin its reaction so the other main benefit is it can become a nuclear waste reduction process by utilising the stockpiles of waste as a means of initiating Thorium fission. This should be understood as the obvious next step in the Nuclear technology strategy. Using an MSR based on a Thorium fuel (LFTR – Liquid Floride Thorium Reactor) in a thermal spectrum reactor seems to have many advantages and should be the ideal option to pursue. The guys at ORNL would shut down on Friday for their weekend break and restart on Monday without any hitches. Any engineer would jump at the chance to improve the burnup yield efficiency to such an extent while using such an inherently safe process?
While entrenched in the past technology there appears a conundrum where the appeal of far-fetched future technologies sits more comfortably than those within easier reach. It would seem the moon-shot for Fusion Reactors grabs the headlines (and the funding) where a blind spot exists for the more practical step of a ‘walk-away’ safe, more efficient, proliferation resistant, waste reducing, MSR Thorium based Fission Reactor … that requires no huge input power to initiate & control it … just real commitment to invest as this is far too important an issue to depend only on the good intentions of charitable organisations, such as the Alvin Weinberg Foundation, to progress!
I accept the word of the physics boffins who say that Tokomaks will work. They should accept the word of engineers who say they have zero chance of producing low cost electricity.
Molten Salt reactors are a better bet – working on known principles that were demonstrated decades go.
For fusion, there is more chance of newer designs making a break through – for example Helion Energy, who are making a pulsed fusion device, or laser fusion (US DoE funded) or Polywell fusion (funded by US DoD). ITER may be a fun research project – but it’s not the future for electricity generation.