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
Could nuclear fusion energy power the future? – with Melanie Windridge (Royal Institution video)
Gaia Vince, Transcendence, 2019
https://en.wikipedia.org/wiki/Aneutronic_fusion
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