Archive for the ‘future energy’ Category
Thoughts on energy – crisis and survival
coal-fired power plant, Germany
Recently I was talking to my language group about climate change, or global warming as I prefer to call it, and I uttered the deepity that heat equals energy, and I even wrote it up on the whiteboard as an ‘equation’ of sorts.
I was making the simple but important point that stuff in the environment, particularly air and water, moves around faster when heated up, just as it slows down when cooled, or frozen, the reason why freezers and fridges are so useful. So from an environmental perspective, heat means more volatility, more movement, more action, like a pot of water on the stove, which can be pretty disastrous for the biosphere.
Useful enough as far as it goes, but of course there’s much more to energy than this. I’m reading, inter alia, How the world really works, by Vaclav Smil, the first chapter of which is titled ‘Understanding energy’. He quotes Richard Feynman:
It is important to understand that in physics today we have no knowledge of what energy is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. However, there are formulas for calculating some numerical quantity, and when we add it all together it gives… always the same number. It is an abstract thing in that it doesn’t tell us the mechanism or the reasons for the various formulas.
V Smil, How the world really works, p23
Energy is something we get from something, something that is energetic, like our sun. Water falling down a waterfall has kinetic energy, or gravitational energy. Plants absorb energy from the sun to fuel a super-complex process called photosynthesis, described in detail in Oliver Morton’s Eating the sun, one of the most intellectually demanding books I’ve ever read. We’ve discovered, over the past few centuries, that fossilised plant material, starting with coal, is a rich source of energy, much richer than wooden logs set alight.
We started to get a ‘modern’ sense of energy through the development of physical laws. Newton’s second law of motion is key here. It basically states that the acceleration of an object (a state of disequilibrium) is due to an unbalanced force, and this acceleration is dependent upon the object’s mass and the force acting upon it. This three-way relationship is usually presented as F = m.a, or a = F/m. Or, as Smil puts it:
Using modern scientific units, 1 joule is the force of 1 newton – that is, the mass of 1 kilogram accelerated by 1 m/s² acting over a distance of I metre.
Needless to say, this isn’t how people without training in physics think of energy. The ‘capacity for doing work’ is one way of putting it – and J C Maxwell tried a physical definition of work as ‘[an] act of producing a change of configuration in a system in opposition to a force which resists that change’.
Whether or not it can be described as work, energy surely changes stuff. The energy of the sun not only changes plants (photosynthesis) but also our oceans and lakes (evaporation), and the make-up of the sun itself (nuclear fusion).
And living things expend energy in doing work – to obtain and consume food (other living things) to provide energy to go on living and working. And over time we humans have evolved to look for and find ways to obtain more energy via less work. Or perhaps it would be more accurate to say we’ve evolved ways of doing this, as a collective species, more effectively and successfully than any other living thing, and at the expense of many other living things.
This is a bit of a problem for us. Unlike other living things, we know that we’re totally reliant on the biosphere that we dominate. That our survival and thriving depends upon the living stuff that we kill. And much of that stuff – grains, legumes, fungi, root vegetables, as well as poultry, fish, lambs and cattle – we bring to life for the sole purpose of killing them, in multi-billion dollar industries. And yet we must eat, and we really enjoy doing so, or are habituated, in an affluent society, to mix with others in interactions associated with food. We’ve certainly gone beyond thoughts, in the WEIRD world, that we must eat to stave off starvation, or to top up our energy.
We require energy for other things. Travel, thought, conversation, exploration, domination. And this has required more ‘efficient’ forms of energy. More output for less input (at least from we humans). Outsourcing work to machines, fuelled by non-human sources of energy.
How we came to understand that fossil deposits – first coal, then crude oil, then methane or ‘natural gas’ – could be exploited as seemingly limitless energy sources requires a separate blog post, and involves many individual contributors, both theoretical and practical. And in exploiting that energy we didn’t realise, or much care, that it might come at a cost. We rode that energy bonanza, and the human population rose from one billion, ‘achieved’ in the middle of the 19th century, to 8 billion today, and counting, with a billion added every 13 years at current rates.
This has been very successful, in the short term. I used to think about this with the analogy of bacteria in a Petri dish, multiplying exponentially, then collapsing spectacularly when all the nutrients are consumed. But we’re not bacteria, and the nutrient situation in a Petri dish bears little comparison to that of our evolving, dynamic biosphere. We, as a species, have evolved the capability of adapting to transformations to our environment, of our own making, in order to survive those transformations – by transforming those transformations. That’s what we do. Indeed that’s what we must do, to survive, and thrive.
I’m not extolling our virtues here. My view re humanity, FWIW, lies somewhere between the ‘beginning of infinity’ all-conquering optimism of David Deutsch and the eternal-present ‘seeing’ of John Gray (Straw Dogs). We plan for our future because we want to endure, and unlike other species, we know that there is a future, a human future, beyond our individual selves. And we want that future to be successful, whatever that means.
So, returning to energy – can we find ways to transform our energy supply so that we can sustain ourselves while minimising the damage to the web of other life? At present, we’re having no problems multiplying our own species, but other species, apart from those we’ve learned to exploit for food, are diminishing and disappearing. And yet, there’s much talk of the value of human diversity.
I’ve written about energy futures elsewhere. The continuing exploration and development of nuclear fusion, improvements in fission technology, improving the energy efficiency and versatility of solar panels and surfaces, developments in materials science, recycling technologies and so on. All of this is important, and often exciting. We also have to refocus our energy sources to be less exploitative of other species – less reproduction for slaughter, which is not only unnecessarily cruel but also wasteful of land and other resources, especially for large grazing and consuming species. Gaia Vince reports on the ‘fake meat’ business that I’ve written about in the past:
Producers are using biotechnology to create fake meats that bleed like beef – the Impossible Burger is made from a soy protein with a yeast that has been genetically modified to produce leghaemoglobin, an iron-carrying molecule like haemoglobin that gives the burger its meaty bloodiness. However most of what we enjoy about meat is the taste and aroma of the Maillard chemical reaction: this is the fusion of sugars and amino acids that occurs when the food browns during cooking. This can now be convincingly replicated with plant-based molecules.
G Vince, Nomad century, p161
According to a report cited by Vince, ‘within 15 years the rise of cell-based meat will bankrupt the US’s beef industry, at the same time removing the need to grow soya and maize for feed’. Sounds a bit optimistic, but watch this space.
Clearly the future for us, and for a healthy, diverse biosphere, depends on a transformation of our energy production and use. And to be fair to our collective selves we need to help and protect those who are suffering most from our impact on the biosphere, a suffering disproportionately felt by those who’ve had the least impact. My guess is that the transformation will come, but too late for too many. We’re great survivors, but terribly selfish.
References
Vaclav Smil, How the world really works, 2022
https://www.physicsclassroom.com/class/newtlaws/Lesson-3/Newton-s-Second-Law
Gaia Vince, Nomad century, 2022
nuclear fusion 3 – developing technologies
something to do with laser confinement fusion energy
Ways of producing nuclear fusion:
- High-temperature superconductors (HTS) for magnetic confinement fusion.
HTS is all about producing more powerful magnets, in order to effectively confine super-hot (100 million degrees Celsius) plasma. Traditional electrically conducting materials such as copper will lose conductivity and become resistant at high temperatures, causing them to over-heat. To eliminate electrical resistance from potential superconducting materials, they need to be cooled to -269 Celsius. I’m trying to get my head around this, so I’m following the demo in the Royal Institution lecture linked below. A small but powerful magnet was dropped into a hollow copper tube, held vertically. It finally emerged from the bottom, but not at the pace of gravity. It’s all about the peculiar relationship between magnetism and electricity. The magnet creates a moving magnetic field inside the copper tube, inducing an electrical current, which, somehow, creates its own magnetic field in opposition to the field from the magnet, pushing back… (somehow I feel I should’ve done a Canto and Jacinta on this one!)
So, as the demonstrator tells us, we can vary the electrical resistance of metals, for example by increasing or reducing their temperature, as described above. Warming the copper tube increases its resistance, cooling it will decrease its resistance. A further demonstration with the same magnet and a very much cooled copper tube (-196 Celsius) showed that the magnet took longer to move down the tube. I don’t really understand how that proves decreased resistance, but then I’m no physicist… But the demonstrator explains:
So with the reduction in the resistance of the copper, those currents are able to form and flow more easily, and therefore they have a stronger magnetic field, opposing the falling magnetic field of the magnet [my emphasis].
So that clarifies things a bit. And the aim is to remove all electrical resistance, if possible. This can’t be done with most metals, including copper. And so – superconductors. There are apparently, high-temperature superconductors and low-temperature superconductors, the latter being the ones that need to be cooled down to -269 Celsius. So the demonstrator proceeds to demonstrate the effect of a dose of liquid nitrogen on a potential HTS, described rather vaguely as a ‘ small chip of super[lux??]’. I’ve tried looking up what he meant here (the captions didn’t help), but have come up empty. I’m guessing that he’s simply doused the same ‘small but powerful’ magnet. Anyway, the doused chip sits in a polystyrene cup which is sitting on a circular magnetic track. The supercooling is designed to turn it into a HTS, presumably. The aim is to repel the field from the magnetic track ‘by setting up its own internal currents’ in balanced opposition. The chip has to be doused a couple of times with the liquid nitrogen to get it to the right temperature, but the demonstrator soon has the cup with its ‘chip’ riding on the magnetic rail like a wee whited coaltruck, back and forth with a fingerpush.
Presumably the chip will have to be kept at this temperature to maintain this internal current. It will regain its electrical resistance upon warming up to a certain point. The second demonstrator shows us a HTS tape, which, when cooled down to 20 degrees Kelvin (that’s less than -250 celsius), will carry five times its normal electric current, with no resistance. Wound into a tight coil, the material, which is super-thin, will have a much higher energy or current density, which can be used to generate a strong magnetic field. The more material in the coil, the greater the current density, until the magnetic field is strong enough to safely confine the plasma from nuclear fusion. A scaled-up version of this type of coil is used at ITER. They require far less energy to cool them down too. Tokamak Energy is using these coils, combined with a spherical ‘cored apple’ tokamak shape, which apparently makes more effective use of the magnetic field. Altogether, a more efficient design – they hope. Developed in he UK, it’s being used also by the STEP plant (ST for Spherical Tokamak).
2. Laser fusion with diode pumps
Laser fusion is the next technology Windridge discusses. So how do lasers work? From memory, LASER stands for Light Amplification through Stimulated Emission of Radiation, but that don’t tell me much. Anyway it’s all about diode pumps. Wikipedia gives this elaboration:
A diode-pumped solid-state laser (DPSSL) is a solid-state laser made by pumping a solid gain medium, for example, a ruby or a neodymium-doped YAG crystal, with a laser diode
I think I’ll stick with Windridge’s description. We see some images, first of a pink rod of ruby crystal, the ‘lasing material’, wrapped round by a coil of incandescent lighting, which sends a flash of light into the crystal, exciting its atoms and somehow generating photons, all of the same wavelength. The ruby and the coil are enclosed in a capsule, and the generated photons bounce back and forth between mirrors at either end of the capsule, triggering the release of more photons in a build-up of energy. Finally, a beam of energy emerges ‘through a partially reflective mirror at one end’. How this creates fusion energy, I’ve no idea. I vaguely get the sense of pumping but…
Here’s a useful definition of a diode from a website called Fluke:
A diode is a semiconductor device that essentially acts as a one-way switch for current. It allows current to flow easily in one direction, but severely restricts current from flowing in the opposite direction.
It seems that the key here is to produce photons of a particular wavelength. Windridge compares a diode pump with a flash lamp or incandescent bulb. While the flash lamp produces this wide range of energies or wavelengths, but a more targeted, precisely defined energy level is all that is required to excite the crystal photons, meaning it can be done with less waste of heat-energy. Diode lasers are many times more efficient than the NIF laser, for example – nearly 40 times more efficient (the NIF laser uses flash lamps). Remember, NIF (the National Ignition Facility) made headlines some months ago by getting more energy out of their fusion experiment than they put into targeting and ‘igniting’ the fusion pellet, but critics noted that the energy needed to drive the laser was orders of magnitude greater than the energy produced. The diode pump may, if found to be workable, reduce those orders of magnitude considerably.
So, although I don’t quite understand all the details, to put it mildly. I do get a strong sense that progress is being made. We seem to have gone beyond proof of concept, and are entering the engineering phase, and it looks like the next couple of decades will some exciting results. Tritium breeding and handling (it’s extremely rare and radioactive) is a big issue, and new materials science will be required to deal with high-energy neutrons and the damage they cause. Producing and testing such materials will be a high priority, but the pay-off can hardly be calculated. High-temperature superconductors are a relatively new development, and perhaps more breakthroughs can be made there. With more money being poured in, there will be more jobs for smart people – can-do problem solvers.
So, after watching this video a couple of times and trying with limited success to understand the science, but understanding enough to be aware of the viability of something that once would have seemed the most impossible of dreams – replicating the vast power of the stars – I read many of the comments, and was dismayed by the high level of negativity. An almost ferocious naysaying. I could respond with Kafka’s ‘genius doesn’t complain, but runs straight against the wind’, or ‘We choose to go to the moon, not because it is easy but because it is hard’, by that Kennedy bloke. It was just a little less than a century ago that Hubble provided convincing evidence that other galaxies existed. Two centuries ago we knew nothing of atoms or genes or space-time. The progress we’ve made science since then is – well, astronomical. Of course, new breakthroughs tend to create new problems, and I can imagine science-fiction scenarios in which our play with fusion ends up in our going up in a sunburst of glory – ‘Out, brief candle!’
We shall see. I hope I can live so long…
References
https://en.wikipedia.org/wiki/Diode-pumped_solid-state_laser
https://www.fluke.com/en-au/learn/blog/electrical/what-is-a-diode
nuclear fusion developments 2 – replicating the stars
ITER, in southern France, while under construction
Returning to nuclear fusion, I’m focussing here on the recent Royal Institute lecture mentioned in my previous fusion post (all links below). Dr Melanie Windridge starts off with the well-known point that we’re currently failing to reach projected targets for the reduction of global warming, with current national pledges taking us to 2.4 degrees C by century’s end (the target, remember, is/was 1.5°C), with energy demand rising, and energy security issues due to political instability, among other problems.
Windridge’s pitch is that, yes, we must keep on with all the possible green solutions, but fusion is the transformational solution the world needs. It potentially produces no CO2, an abundant supply of fuel, in a safe, controlled process with no long-term radioactive waste. It would also potentially produce firm, non-intermittent, base-load power – less redundancy in the grid (I probably need to do a whole post on this) – which would be more economical in the long term. Also, decarbonisation is about much more than electricity, which apparently is only about 20% of the electricity market. The other 80% is much harder to decarbonise. Windridge lists some of them – industrial heat, aviation and shipping fuels, and desalination – which I hope to explore further in another post. There’s also the opportunity, if we could develop an effective fusion energy system, with limitless clean energy, of undoing the damage already done. Current projections show that there will still be fossil fuel-based energy in the mix in 2050. This is a challenge for those interested in pursuing the fusion solution. ‘Fusion can address the fossil fuel gap’, one of Windridge’s graphs suggests. The aim, it seems to me, is that fusion will be ‘ready’ by mid-century, at which time it will be transformative or, as Windridge says ‘we need a solution with immense potential’. But prediction is tricky, especially about the future, and as a sixty-something optimist, I can only hope that I can live and be compos mentis enough to witness this transformation.
Frankly, it’s amazing that we can be considering this type of energy, a result of relatively recent understanding of our universe. As Windridge points out, the only other form of energy that is more energy-dense is matter-anti-matter annihilation (from the first few seconds after the ‘Big Bang’) – I can well imagine future researchers and engineers trying to create a Big Bang under controlled conditions in some hyper-complex cybernetic laboratory. I wouldn’t be surprised if an SF author has already written a story…
High energy density is doubtless the holy grail of future energy technology. Windridge gives a nice historical account of this – something that Gaia Vince’s Transcendence has helped me to focus on. The industrial revolution, which began in Britain, moved us from animal energy in joules per gramme to chemical energy in kilojoules (one thousand joules per gramme). This gave Britain a fantastic edge over the rest of the world, and was the vital element in creating the British Empire. Nuclear energy, which takes us to gigajoules (billions of joules) per gramme, and which, thankfully, is being pursued internationally, and hopefully collaboratively, is a breakthrough, if it works out, comparable to the invention of fire. One kg of fusion fuel can provide as much energy as 10 million kg of coal, so it would make sense to concentrate much of our collective ingenuity on this zero-carbon form of fuel.
There are different pathways. Aneutronic fusion, as the name suggests, doesn’t rely so much on neutron energy, with its associated ionising radiation. Alpha particles or protons carry the energy. An Australian company, HB11 Energy, is using lasers to drive a low-temperature proton-boron fusion system, which is showing some promise, and deuterium-helium-3 is another combination, but currently deuterium and tritium is the easiest reaction to obtain results from. Now, considering the power of the sun, which is so energetic that, according to BBC Science Focus, ‘the Earth would become uninhabitable if its average distance from the Sun was reduced by as little as 1.5 million km – which is only about four times the Moon’s distance from Earth’, it should be pretty clear that recreating that kind of energy here on Earth’s surface is fraught with problems. The fusion ‘triple product’ for producing this energy is apparently heat, density and time. So to achieve the product in a ‘short’ time, for example, we need to tighten the other parameters – more heat and density. Safely producing temperatures much higher than those in the sun for any extended period would presumably be quite a feat of engineering. The different designs and approaches currently include tokamaks, stellarators, inertial confinement (using lasers) and magneto-inertial fusion. The inertial confinement laser model focuses lasers on a small fuel pellet, causing it to implode and produce ‘fusion conditions’.
It’s all about producing plasma of course – the so-called fourth and most energetic state of matter. Electrically-charged particles which make up over 99% of the visible universe. These charged particles spin around magnetic field lines, so allowing us to use magnetic systems to control the material. We’ve used plasma in neon lights for over a century, and its production was first demonstrated by Humphrey Davy in the early 1900s – something to explore…. Plasma is also a feature of lightning, a ‘bolt’ of which can strip electrons from the immediately surrounding air. This means that air is ionised and can be manipulated magnetically. Tokamaks and other magnetic devices operate on this principle.
Inertial confinement uses shock waves or lasers to ‘squeeze’ energy out of a pellet of fusion fuel. The point at which such energy is produced is called ignition. Think of a bicycle tyre heating up as you pump it up to a higher pressure, until the tyre explodes – sort of.
So – and I’m heavily relying on the Windridge public lecture here – fusion research really began in the fifties, generally in universities and public labs. This early work has culminated in two major public projects, ITER (the International Thermonuclear Experimental Reactor), with its ultra-massive tokamak located in the south of France, and NIF, the National Ignition Facility, located in California. which made headlines last December for ‘the first instance of scientific breakeven controlled fusion’. This involved bombardment of a pellet ‘smaller than a peppercorn’ to produce a non-negligable energy output for a very brief period.
All of this has been at great public expense (why weren’t we told?), so in more recent times, private investment is moving things along. The last couple of years has seen quite a bit of progress, in both public and private facilities. For example, JET, in Oxfordshire, produced 59 megajoules (59,000,000 joules) of fusion energy, sustained for 5 seconds, a world record and a proof of concept for more sustainable energy production. And at NIF last year they produced ‘ignition’, the whole point of the facility, producing more fusion energy than the laser energy used to drive the process, a proof of concept for controlled fusion. And even more recently, China set a new record at their EAST tokamak (don’t you just love these territorial names), attaining steady-state ‘high performance’ plasma for about 6.5 minutes (I don’t know what high performance plasma is, but I can perhaps guess). And there is a lot of work going on in the private space too (I’ll be looking at Sabine Hossenfelder’s appraisal of the field in a future post, all in the name of education), with a really notable increase in private investment and start-ups – about half of the world’s private fusion companies today are less than 5 years old. Some $5 billion has been invested, from energy companies like Shell and Chevron, but also a variety of other organisations familiar to capitalists like me.
Why is this happening? Clearly we have a greater consensus about global warming than existed a decade ago. Also the science of fusion has reached a stage where rich people and organisations are sensing the opportunity to make even more money. Windridge also talks about ‘enabling technologies’, recent engineering and technological developments such as high-temperature superconductors, diode pumps for lasers, and various AI breakthroughs and improvements. Mastering and streamlining these developments will ultimately reduce costs, as well as expanding the range of the possible. National governments are developing regulatory frameworks and ‘fusion strategies’ – the latest coming from Japan – often involving public-private partnerships, such as the UK’s Fusion Industry Programme. The UK has also created a facility called STEP – the Spherical Tokamak for Energy Production – run by the Atomic Energy Authority, which is described by Windridge as the world’s first pilot nuclear energy plant.
So in the next post on this topic I’ll be trying to get my head around the developments mentioned above, FWIW. And it is definitely worth something. If we can get it all right.
References
Gaia Vince, Transcendence, 2019
https://en.wikipedia.org/wiki/Aneutronic_fusion
https://www.psfc.mit.edu/vision/what_is_plasma
https://fusionenergyinsights.com/blog
nuclear fusion developments 1
This post is also published on my Solutions OK blog.
As a person much addicted to reading, I’ve been impressed by a writer who’s been eloquently cataloguing global problems and solutions in the Anthropocene. Gaia Vince (I presume her parents were Lovelock fans) has written 3 books, Adventures in the Anthropocene, Transcendence and Nomad century, the first two of which I now possess, the first of which I’ve read, the second of which I’m well into, and the third of which I intend to buy. So, time to return to my own self-education notes on solutions…
Vince appears to be my opposite – adventurous, extrovert, successful, in demand, and doubtless eloquent in person as well as in print. Bitch! Sorry, lost it there for a mo. The heroes and heroines of her first book, the product of travels though Asia, South America, Africa and the WEIRD world, and the solutions they’ve created and pursued, will, I think, provide me with pabulum for many blog pieces as I sit, impoverished (but not by global standards), uneducated (in a formal sense) and unlamented in rented digs in attractive and out-of- the-way, Adelaide, Australia, once touted as the ‘Athens of the South’ (at least by Adelaideans).
What I’ve found in my research on solutions – and Vince’s explorations have generally borne this out – is that solutions to global or local problems have created more problems which have led to more solutions in a perhaps virtuous circle that’s a testament to human ingenuity. And the fact that we’re now 8 billion, with a rising population but a gradually slowing rate of rising (in spite of Elon Musk), shows that we’re successful and trying to deal with our success…
So what are our Anthropocene problems? Global warming, of course. Destruction of other-species habitats on land and sea. Damming of rivers – advantaging some groups and even nations over others. Rapid industrial change (I’ve worked – mostly briefly! – in a half-dozen factories, all of which no longer exist). Population growth – in the 20th century from less than 2 billion to over 6 billion, and over 8 billion by May 2023. Toxic waste, plastic, throwaway societies, social media addiction and polarisation, the ever-looming threat of nuclear warfare… and that’s enough for now.
But on a more personal level, there’s the problem of how to navigate the WEIRD world, a world that bases itself on individualism, that’s to say individual freedom, when you don’t believe in free will (or rather, when you’re certain that free will is bullshit). And yet… a lot of smart, productive people don’t believe in free will (Sam Harris, Robert Sapolsky, Sabine Hossenfelder), and it doesn’t seem to affect their activities and explorations one bit – and to be honest it doesn’t affect my work, such as it is, either, though it does provide me with a handy excuse for my failings. My introversion has been ingrained from earliest childhood (see the Dunedin study on personality types and their stability throughout life), my lack of academic success has been largely due to my toxic family background, bullying at school, and lack of mentoring during the crucial learning period (from 5 to 65?), and my lifelong poverty (within the context of a highly affluent society) is not entirely due to laziness, but more to do with extreme anti-authoritarianism (hatred of ‘working for the man’) and a host of other issues for which I blame my parents, my social milieu, my genes and many other determining factors which I’m determined not to think about right now.
Anyway, with no free will we humans have managed transformational things vis-à-vis the biosphere, and there will be more to come. In her epilogue to Adventures in the Anthropocene, Vince hazards some predictions, using the narrative of someone looking back on the century from the year 2100, and considering the book is already about ten years old, I might use the next few posts to look at how they’re faring.
So – nuclear fusion. Here’s Vince’s take:
In 2050, the first full-scale nuclear fusion power plant opened in Germany (after successful experiments at ITER, in France, in the 2030s), and by 2065 there were thirty around the world, supplying one-third of global electricity. Now, fusion provides more than half of the world’s power, with solar making up around 40% and hydro, wind and waste (biomass) making up the rest.
So I’m starting with a very recent video by the brilliant Matt Ferrell, as a refresher for myself. Nuclear fusion, the source of the sun and stars’ energy, involves two small atoms colliding to form a larger atom (e.g. hydrogen forming helium), with some mass being converted to energy in the process. And I mean a really large amount of energy. To quote Ferrell:
Once the fusion reaction is established in a reactor like a tokamak, a fuel is required to sustain it. There’s a few different fuels that are options: deuterium, tritium or helium-3. The first two are heavy isotopes of hydrogen… most fusion research is eyeing deuterium plus tritium because of the larger potential energy output.
The power released from fusion is much greater, potentially, than that derived from fission. And deuterium plus tritium produces neutrons, which creates a process called neutron activation, which induces relatively short-lived but problematic radioactivity. And there are a host of other challenges, but it’s clear that incremental progress is happening. People may have heard of JET (the Joint European Torus) and the unfinished ITER (the International Thermonuclear Experimental Reactor), and of recent promising developments – for example, this:
A breakthrough in December 2022 resulted in an NIF [Nuclear Ignition Facility] experiment demonstrating the fundamental scientific basis for inertial confinement fusion energy for the first time. The experiment created fusion ignition when using 192 laser beams to deliver more than 2 MJ of ultraviolet energy to a deuterium-tritium fuel pellet.
Ferrell visited the Culham Science Centre, near Oxford in the UK, where he was shown through the RACE (Remote Applications in Challenging Environments) facility, a perfect acronym for the time. They’ve created a system there called MASCOT, which appears to be a cyborg sort of thing, but mostly mechanical – with a human operator. The aim is to incrementally develop complete automation for maintenance and upgrading of these highly sensitive and potentially dangerous components. Since everything is still at the experimental stage, with a lot of chopping and changing, flexible human minds are still required. Full automation is clearly the goal, once a reactor is up and running, which is still far from the case. Currently, it requires about a thousand hours of training to work with the machinery and the haptics in this pre-full automation stage, bearing in mind that the types of robotic and cable systems are still being worked out. Radiation tolerance is an important factor in terms of future developments. Culham uses a ‘life-size’ replica of a tokamak for training purposes.
RACE, as the acronym suggests, is not just a facility for nuclear research but for dealing with hazardous environments and materials in general. Moving on from JET, Ferrell visited the new MAST-U (Mega Amp Spherical Tokamak – Upgraded!). As Ferrell points out, the long lag time between promise and results in nuclear fusion has often been the butt of jokes, but this ignores many big recent developments, described well by Dr Melanie Windridge in a Royal Institute lecture, of which more later.
In the video we see a real tokamak from the sixties, probably the first ever, sitting on a table, to indicate the progress made. MAST-U’s major focus at present is plasma exhaust and its management, essential for commercial fusion power. Its new plasma exhaust system is called Super-X, a load-reducing divertor technology vis-a-vis power and heat, so increasing component lifespans. One of the scientists described the divertor as like the handle in a hot cup of coffee:
So our plasma is the coffee that we want to drink. It’s what we want, right? We want this coffee as hot as possible, but we won’t be able to handle it with our hands, we need a handle, and the diverter has the same function, it tries to separate this hot, energetic plasma from the surface of the device. So we divert the plasma into a different region, a component specifically designed to accommodate this large excess energy.
The divertor is the key factor in the upgrade and is drawing worldwide attention, as it has supposedly improved plasma heat diversion by a factor of ten, as I understand it. And MAST-U’s spherical design is potentially more efficient and cheaper than anything that has gone before. All a step or two towards more viable power plants. And, returning to JET, you can see in the video how massive the system is compared to the table-top version of the sixties. JET came into being in the 80s, and has had to deal with and adapt to many new developments, such as the H-mode or high-confinement mode, a new way of confining and stabilising plasma at higher temperatures, which has gradually become standard, requiring engineering solutions to the torus design. It’s expected that AI will play an increasing role in new incremental modifications. Simulations to test modifications can be done much more quickly, in quicker iterations, via these advances. AI, computer modelling and advances in materials science and superconductors are all quickening the process. JET will be decommissioned in about 12 months, but much is expected to be gleaned from this too, as they look at how neutrons have affected material components.
Another issue for the future is tritium, supplies of which are currently insufficient for commercial fusion production. According to ITER, current supply is estimated at 20 kilos, but tritium can be produced, or ‘bred’ within the tokamak through the interaction of escaping neutrons with lithium. Creating a successful tritium breeding system is essential due to the lack of external sources.
So that’s enough for now, I’ve gone on too long. To be continued.
References
Gaia Vince, Adventures in the Anthropocene, 2014.
https://www.iter.org/mach/TritiumBreeding