If nuclear fusion can be tamed on earth then it offers the potential of limitless energy for the foreseeable future. We saw in the previous post how all the elements on earth were fused in a massive star that exploded before our sun formed. Today all the energy for life on earth originates from the nuclear fusion reactions in the sun, with the exception of a small amount of geothermal energy from nuclear (fission) decay. In that sense it is already the case that we depend on fusion energy for our existence. Even renewable energy can be thought of as just a low level spin off of fusion energy (the sun). Therefore it would be infinitely better if we could somehow tame nuclear fusion as an energy source here on earth. There are also huge advantages if this can be achieved.
- Cheap and limitless supply of ‘fuel’ mainly from sea water
- Fusion is inherently ‘safe’. The reaction cannot run away because so little fuel is being ‘burned’ at any one time.
- It produces no CO2
- It produces only low levels of radioactive waste, which becomes completely negligible after ~100 years.
Scientists and engineers have been working on controlled fusion for about 60 years. Unfortunately it has proved so far to be frustratingly difficult to achieve the conditions needed, and there is as yet no silver bullet. There is a standing joke that fusion is always 30 years away and always will be. However despite this, there has been steady progress and fusion really is now within our grasp. Two technologies even promise a potential breakthrough – high speed computing and superconductivity.
The simplest reaction to achieve on earth is the fusion of deuterium and tritium. It has the highest cross-section which translates into the lowest temperature and density requirements.
To produce significant amounts of fusion power from a plasma of deuterium and tritium one needs to heat the plasma to nearly 100 million C, and then contain it long enough for the fuel to ‘ignite’ and self maintain fusion power. For ignition to occur the heat transferred to the plasma via the 3.5 MeV 4He nucleus must be greater than all energy losses from the plasma. There are two main ways that the plasma can lose energy. Firstly the neutron ( which being neutral) simply escapes the plasma. However this neutron can be captured in an external blanket to extract energy for electricity production and also be used to breed new tritium from Lithium. The second way the plasma loses energy is through losses of the plasma itself to the wall or diverter plates caused by instabilities. There are two methods currently under development to heat and contain a plasma to fusion conditions on earth. Both promises to lead to ignition and electrical power production.
Inertial Confinement
The goal of inertial confinement is to trigger a tiny thermonuclear explosion (yes a mini-hydrogen bomb!) using powerful laser beams. A small cell of DT is placed at the focus or target of a very powerful array of laser beams which produce 500 Terawatt of power for just a billionth of a second. If all that energy could be used to heat the pellet then it will ignite emitting terajoules of fusion energy. This heat is extracted from the neutrons by surrounding the taget with a blanket of water. Lithium is also needed to breed more tritium fuel. Pellets could then be drip fed into the target to produce a type of pulsed fusion engine. The heat absorbed by the water coolers then drives turbines to produce power. The largest facility in the world is the National Ignition Facility at Los Alamos built in 2009, and intended to demonstrate ignition. So far it has achieved only net energy breakeven but not ignition. The problem is that you need a perfect symmetry of implosion to stop the pellet flying apart before ignition can occur and so far these conditions have not been achieved. NIF has been a slight disappointment and is still a factor 3 below ignition. One of the problems has been Rayleigh instabilities in the ablative sphere enclosure radiating energy away from the implosion.
A working ‘inertial fusion’ power reactor is still decades away.
Magnetic Confinement
This is the most favoured solution for a future power reactor and uses magnetic fields to contain the plasma. Charged particles spiral along magnetic field lines between collisions. The higher the field strength the better the confinement. Magnetic confinement has a long history dating back to the Zeta experiment in 1957 at Harwell.
Today there are two main configurations which promise to eventually realise fusion power. The main contender is the Tokamak configuration and the largest experiment so far was JET based at Culham. A tokamak has a toroidal field in the shape of a doughnut and a poloidal field which adds a helical twist and is used to heat the plasma by generating a large current like a transformer. Further heating of the plasma then is made through radio frequency waves and by neutral beam injection. The former inputs electromagnetic energy into the ions and the latter injects fast deuterium atoms which then are ionised and lose energy through collisions.
A difficulty for tokamaks is to avoid the plasma touching the walls as this causes impurities (heavy ions) to be introduced which can rapidly cool the plasma. For that reason the walls are coated with beryllium and a special device called a ‘diverter’ is designed to divert ions leaving the plasma onto specialised plates before they can collide with the wall. Eventually diverters can also be used to process exhaust from a burning plasma. Another problem are the development of instabilities or turbulence in the plasma which can be controlled by magnetic feedback on the poloidal field coils to stabilise them. The tokamak uses a transformer like ‘pulse’ to generate a large current in a freshly introduced plasma which is then heated through so-called Ohmic heating, just like an electric fire. The plasma current reaches over 5Mamps.
This current is still not enough to heat the plasma to the temperatures required for fusion so external heating by neutral beams and RF is needed. Neutral beams may also be used to generate a steady state current needed for a burning plasma once the initial transformer pulse has ended. This is called current drive.
In 1998 Jet achieved the world record of 15MW of fusion power in a DT plasma which equals a Q-value of 0.7. Q=1 corresponds to energy breakeven whereby the fusion energy produced is equal to the energy input to heat the plasma. Q values greater than 10 are needed for any future power reactor. A burning plasma after ignition needs zero energy input, because all the heating would be generated by collisions with the 5MeV alpha particles produced.
Performance of Tokamacs are characterised by a small number of parameters. A fundamental index is the energy confinement time.
This measures how well the plasma is insulated by the magnetic field. If there were no energy losses 
Progress of Tokamacs towards Fusion. We are really not that far away from energy gains Q>10 and ignition. ITER should achieve this.
ITER
The ITER (International Tokamak Fusion Reactor) tokamak finally being built now in France after years of political delays. It is an international project based on a scaled up version of JET, with a stronger toroidal field made possible with super-conducting magnets. It is designed to produce 600MW of fusion power and test the feasibility of breeding tritium from Lithium, current drive, and basic components needed to build a demonstration (DEMO) power reactor. This DEMO is foreseen to be operational around 2040 at the earliest and should generate about 1GW of electrical energy. There is no doubt now that ITER will work, but whether it can be proved economic and reliable enough are the key issues. For example the radiation damage to the first wall problem needs to be solved. The neutron flux inside a fusion reactor burning DT is such that almost each atom will be displaced over the lifetime, so any material used must be resilient to neutron damage, or at the very least its surface must be easily replaced. The prize though is huge because a fusion reactor is inherently safe and cannot runaway because there is so little fuel present at any moment. Radiation risks to the public are tiny.
Another challenge for ITER is the need to demonstrate the breeding of Tritium on site for use as the fuel. Tritium has a half life of just over 12 years so it needs to be generated artificially. This can be done by using the neutron flux from the reactor and an external blanket of Lithium.
The tritium cycle can all be implemented on-site as a closed loop. Essentially the ‘fuel’ needed for a fusion reactor is simply deuterium and Lithium, both of which are very abundant in nature. These technical challenges must be solved on ITER before a power reactor can be built.
Alternatives to ITER: Stelerator
One drawback of tokamacs is that the magnetic field is stronger on the inside than the outside due to simple toroidal geometry. This is one cause of instabilities and plasma losses to the outside wall. One way round this is to twist the configuration so as to invert inside and outside magnetic loops using a complex magnetic field configuration called a stelerator. The stability of such configurations can be modelled by computer and then implemented with complex engineering. The largest steterator experiment is now being commissioned in Germany and is called Wendelstein 7X.
The plasma needs external heating by microwaves because there is no transformer induced plasma current. If they can reach 100 million degrees with steady state conditions then stelerators would become a viable alternative to tokamacs.
Alternatives to ITER: Spherical Tokamacs
Spherical tokamacs promise to provide much more compact cheaper fusion reactors. Their advantage is that they can maintain a higher plasma pressure by squashing up the tokamak magnetic field by reducing the size of the central size. This means they can be made much smaller so that a fusion reactor with the same output as ITER would be much cheaper. This concept has been developed at Culham Lab, and is now being developed further by a startup company ‘Tokamak Energy’ collaborating with Oxford Instruments who are world leaders in High temperature Superconducting magnets. There was a very recent channel 4 news report from November 4th 2015 (4 days ago at time of writing) explaining the motivation of the company.
Some of the UK’s best known fusion scientists who worked at Culham and Jet are consultants. Culham are also now upgrading their circular tokamak experiment MAST. However most international spending is now based around ITER, which is taking the conservative approach by scaling up JET to develop a research reactor. This leaves an opportunity for a fast evolving company to exploit a possible shortcut by exploiting the encouraging results of sherical tokamaks.
Other Commercial Initiatives
The most interesting recent developments have also been a number of commercial startups working on developing radically different small Fusion reactors. The potential payback is so enormous that either large companies or rich investors are willing to try new approaches not funded otherwise, although many of the ideas are not new. What could be new is the advances in superconducting magnets and fast electronics. Four of the most interesting are:
Lockheed-Martin
Their Skunkworks team are working on a small superconducting magnetic mirror device which they call a Compact Fusion Reactor. Magnetic mirrors are supposed to pinch the magnetic field lines so tightly at each end that high energy ions are reflected and kept within the reaction chamber which is heated with neutral beams. It is designed to fit on the back of a truck and produce 100MW. That way it can be delivered to a town or remote community.
However, details are a bit thin on the ground but they claim to have it all up and working in 5 years. Magnetic mirror devices were tried early on in Fusion research and were not successful. They claim that superconducting magnets and feedback control can resolve energy losses. This is a high risk project with potentially massive payback. The master company is unlikely to continue funding unless results look promising after 5 years.
Tri-Alpha Energy
- Investor Paul Allan
This is the most secretive company. It’s aims are not to use DT fusion but the far harder fusion of p–11B (Boron) which would need temperatures of about a billion kelvin! The big advantage is that the reaction products are free of neutrons generating just three helium nuclei (?-particles). These are charged, so they could be guided by magnetic fields into an ‘inverse cyclotron’ device that would convert their energy into an ordinary electric current very efficiency. The device seems to be a collision of two beams into a magnetic trap heated by neutral beams.
This summer they held a pasma at 10 millionC for 5 milliseconds.They are currently building a new version which they promise will give a 10 fold increase in performance. However they really need a 100 fold increase they achieve their goal.
General Fusion
- Investor Jef Bezos (Amazon)
General Fusion is a Canadian company pursuing what they call Magnetized Target Fusion. It is a mix of intertial and magnetic fusion. In MTF, a compact toroidal magnetized plasma, is compressed mechanically by an imploding conductive shell, heating the plasma to fusion conditions.
General Fusion’s Magnetized Target Fusion system uses a sphere, filled with molten lead-lithium that is pumped to form a vortex. On each pulse, magnetically-confined plasma is injected into the vortex. Around the sphere, an array of pistons impact and drive a pressure wave into the centre of the sphere, compressing the plasma to fusion conditions.
All this sounds good but actually getting it all to work is certainly no easy matter.
Helion Energy
This company is based in Redmont, Washington and has ambitious aims to get D-He3 fusion to work which is even cleaner than D-T fusion because it produces no neutrons. reaction reaction is D + He3 -> He4 + p Such a reaction would produce little radiation damage problems with the reactor wall, and allow direct conversion of electricity from the proton flux. However, it is far more difficult to get this reaction to ignite than DT. Helion aims to build a ‘fusion engine’ based on pulsed magnetic fields to collide and compress two plasma fuel pellets. Again the aim is a truck sized device producing around 100MW. However the details are all a bit thin on the ground.
I am convinced that net fusion power production will be demonstrated sometime within the next 10-20 years. There can be little doubt that it will eventually be made to work and generate electricity. The real question is whether it can be be made economically competitive and cheap enough to replace fossil fuels. The government sponsored ITER approach will succeed but may lead to large, expensive and complex power plants. There are still engineering problems yet to be solved. That is why it is so interesting to see new private ventures seeking to short circuit the whole process. They know that if can can really develop a cheap fusion solution then the pay-off would be enormous.
Nuclear fusion would solve all energy problems essentially for ever. Nuclear fission on the other hand needs fast reactors to be a long term (century scale) solution. Nuclear fusion has two other advantages over nuclear fission.
- It is inherently safe.
- There are no dangers of nuclear proliferation.
This means future fusion power plants could be installed anywhere without serious political or safety problems.
Too much was promised too early for nuclear fusion and the failure to deliver so far has damaged its reputation. The UK spends about £25 million per year in Fusion research which is completely dwarfed by the £5 billion per year it already spends on subsidising renewable energy. The UK was the first to work on controlled nuclear fusion, we hosted the most successful experiment to date JET, and have now developed a promising simple spherical tokomak design. All the commercial startups are based on novel ways to develop small cheap compact fusion reactors producing about 100MW. The North American companies are well funded by rich individuals and venture capital, but I would bet on the UK TokamakEnergy Ltd winning this race if it gets sufficient funding!
Whatever else happens ITER will decide the future of fusion before 2030, and fusion reactors should be generating power in the 2040s.
Or 30 years in the future !
Very helpful article – thanks.
The graph above showing……..
” The progress towards fusion can be shown on a P\tau_e versus T plot.”
………..is very encouraging.”
Such a graph if presented by climate science would guarantee funding of billions!
Thanks Bryan.
Excellent article. A modest word of caution, however. When I was a graduate student in the late 1970s working on methods to heat plasmas to ignition, nuclear fusion was being pitched as a generation away. There was talk of a “Fusion Shippingport Reactor,” that is a small (by fusion standards) reactor producing power sometime around the end of the century. Boeing started up their own division with the idea of bringing in outside ideas from the aerospace industry. At the time, my own view was whatever they are smoking, I wanted some! However, I was only a lowly graduate student who had to please his thesis adviser, so I bit my tongue.
Unfortunately, the most the the optimistic empirical scaling looked like the famous graph of global warming models vs reality. Every time machines were scaled up, some new instability or other issue gave results much less than desirable. A “pause,” so to speak. Two generations later, there has been much real progress in understanding the physics of hot, dense plasmas. We have outside companies, including aerospace, jumping in with new ideas to produce machines quickly. Nuclear fusion is a generation away. Sound familiar?
I don’t doubt that there will eventually be commercial fusion, and it may well come from one of these companies which is looking at alternate approaches. However, I expect that my grandchildren will be the first beneficiaries.
You are probably right. It will take something extraordinary to get fusion working in 10 years time. It seems to have become a sign of our times that progress in many fields has become bogged down in beurocratic and expensive procedures. What used to take 5 years now seems to takes 20. Perhaps Google or someone should put up a $million prize for the first device producing a Q of 10.
As benchmarks are fairly well defined, I would say the UN could better spend their pledges on fusion prizes rather than economically harmful fossil fuel restrictions. Your graph is very helpful to the laymen on the issue. If we could spend the money on fusion that we spend now on climate change awareness we would probably have working fusion by now.
What do we spend on the Large Hadron Collider thing which has so far – as far as I know – done nothing but confirm a conjecture made 50 years ago!
LHC running costs are around $1 billion/year. It did confirm the existence of the Higgs Boson but as yet has not discovered any radical new physics. I started my career in particle physics when the standard model was being developed. I was in the CERN amphitheatre after a night shift, to hear Sam Ting announce the discovery of the J/Psi – or charm quark. A year later Slac discovered the Tau. That was exciting and hopefully LHC may uncover something equally radical such as supersymmetry.
If not it could be the end of the road for experimental High Energy Physics.
Peter, if one thinks about the items humanity typically spends money on, there are plenty of harder items to justify than theoretical physics, the science that will tell us how we got here and where we are going.
Peter, hadron collider is similar white elephant as ”fusion research”, only costs less the taxpayer…
They were fusing hydrogen, then helium, now boron… what next? Both projects are for laundering taxpayer’s$$$ nothing more; – never only kilowatt of electricity will be produced from those; not in a million years, not one watt!!! Nothing to research; process is known, they made the hydrogen bomb long time ago, no secret.
Here is one of the fusion dark horses, Lawrenceville Plasma Physics or LLP focus fusion that apparently runs out of a building with a self-storage business in an industrial section of northern New Jersey, USA. The latest news is Nov 6 — they are looking for funding through its “sixth” stock offering. They are attempting the aneutronic route with a hydrogen-boron reaction so they eliminate radiation and thus have no need for a containment building. And, they can get the energy directly in a small dynamo rather than a large steam turbine. They are using high energy electrolysis to create the plasma and pinching it to create the confinement pressure. They say their working now on reducing the impurities introduced from the anode into the plasma.
If they succeeded it wouldn’t be the first shoestring operation to beat out the big boys. But even at one in a thousand, we could have hundreds more of these projects if prize purses were offered. A prize for a benchmark achievement could give investors a return without having to wager on sales of a fully functional product, encouraging private investment.
Ron, price for those manipulators should be: to share the same jail cell with Bernard Madoff. Fusion process is known – they made the hydrogen bomb, BUT:as it says in my post: fusion is NOT HAPPENING 100 0000km deep into the sun, where is over million degrees, BECAUSE: WITHOUT SUFFICIENT PRESSURE, not on!!!
If they can’t fuse deuterium, the simplest process; to fuse boron…?!?! Do you know what you are talking about?!?!?! Ron, please read my post and stop making fool of yourself..
gentlemen, gentlemen; not in 10 years, not in 10 million years will ever be produced one kilowatt of electricity. NEVER!
For ”fusion” is ESSENTIAL: over 21000C degrees heat and tremendous pressure. We don’t have any metal or alloy that can sustain pressure under that temperature, would melt like butter. Fusion is only for laundering taxpayer’s cash; ”all proven beyond any reasonable doubt”, here: https://globalwarmingdenier.wordpress.com/fusion-for-electricity/
Fusion costs the taxpayers peanuts compared to renewable energy subsidies. The amount of fuel is tiny so a burning plasma can be contained by magnetic fields and the energy extracted by escaping neutrons.
The fusion reactions in the sun are (luckily) extremely unlikely because they depend on the weak interaction. Hydrogen (protons) will not fuse except by first forming deuterium when one proton transforms to a neutron positron and neutrino. Fusion with boron is actually much easier
Today Smithsonian’s Dr. Kenneth M. Towe assured us “Solar eruptions are 100% predictable“.
https://www.researchgate.net/post/Is_there_convincing_evidence_of_AGW#view=5648f4566225ffef5c8b45c0
I am not generally for government subsidies, incentives or interventions, but in the case of fusion its potential is so attractive that it practically must be the ultimate backbone energy source for mankind’s future. For those who say the engineering is too hard, that is what, not the few, but the consensus said about every historic engineering marvel before it was achieved.
The more minds we have working on the problem the faster it will be solved. Breakthroughs happen by realizations or serendipitous recognition of anomalies by those who have been re-attacking a puzzle for years and often times on the verge of giving up.
Ron, IF it was possible, the stars would have discovered that proces long time ago and burned themselves in minutes… In other words: ”researchers for tax$$$” should look FIRST for a metal or alloy, that would sustain that pressure under ”fusion releasing heat / radiation” – before another cent is wasted on the ”sandpit job” OR: strong enough magnet that would sustain the biggest explosions…
Ron, our sun doesn’t have enough ”pressure and heat” to fuse boron – need to go to bigger stars, start packing your bags…
Ron, welcome to the reality!
Thank you your review. The plot of fusion product and ion temperature from various experiments is really encouraging. I will allow myself to get excited about the possibility of fusion power stations in my lifetime (I think I have about 40 years left).
One more time it seems that all enthusiasts, especially those of nuclear energy, have one in common: to dissimulate problems. So here too!
Your post remembers me the good old sixties where we were told all the time that “one kilogram uranium liberates as much energy than the burning of 2800 tons of coal”.
Today everybody doing in this context knows that a complete energetic balance sheet ranging over the full fission context
– from the fuel mining/refining via its enrichment to the reprocessing
– from the construction via maintenance to the dismantling of all involved sites
– including waste vitrification and end storage
reduces the above statement to “the burning of one ton of coal”.
1. “Cheap and limitless supply of ‘fuel’ mainly from sea water”
It’s hard to imagine that people can write such a nonsense at the end of 2015…
Indeed we sit on a lot of deuterium (about 25000 billion tons).
But tritium doen’t exist on earth (in comparison: a few atoms above the oceans and around nuclear plants).
2. “However this neutron can be captured in an external blanket to extract energy for electricity production and also be used to breed new tritium from Lithium. ”
Better would be to be sincere, and to write: “it MUST be captured”.
Simply because there’s no way else to obtain tritium than to breede it out of lithium!
But this breeding can’t be achieved by solely trusting D+T’s brute force but sparse neutronic output: additional neutrons are needed to mute enough lithium to tritium. These are supplied by a suitable neutron source, e.g. beryllium, stored around the lithium within the blankets…
3. “It produces only low levels of radioactive waste, which becomes completely negligible after ~100 years.”
That’s full sweet.
An 800 kg steel structure enclosing 100 kg of lithium and 300 kg of beryllium: that’s a blanket.
These pretty guys must be exchanged every 2 1/2 years, and reprocessed to extract the few tritium that didn’t disappear inbetween (it even moves trough hardest steel).
After reprocessing, all the blanket is waste to be stored for at least 500 (FIVE HUNDRED) years.
The scientists at Germany’s best known Center for nuclear research in Karlsruhe have announced in 2006 that ITER’s successor DEMO will produce at least 60000 tons of waste during a lifetime of 30 years.
4. Thus a fusion reactor – and all the industrial stuff around it – won’t behave much different than the so called “fast breeding reactor technology”, like Superphénix etc etc.
With, as the “cerise sur le gâteau”, a very high probability that a heat transport system similar to that of plutonium breeders, based on about 5000 tons of liquid sodium per installed GWel, will be necessary…
Take a trip to Creys-Malville in southern France! That will help you a bit in evaluating the incredible cost of solely getting rid of that sodium upon deconstruction of the plant.
The main costs in conventional nuclear power are due to the construction costs and the decommissioning costs. The latter is mostly due to the excessive regulations forced through by environmentalists. The fuel costs are minimal.
If you apply the same decommissioning costs to wind energy then the providers would also be required to return the site to a green field, which involves the safe disposal of 1000’s of tons of concrete and rusting towers. That would only be fair wouldn’t it ?
Now your points:
1) The two sources of fuel are deuterium and lithium, both of which are abundant in nature. Eventually D-D fusion may be made to work which then only requires deuterium – available from sea water.
2) Breeding Tritium from Lithium is rather well understood, and you really don’t need very much tritium for a fusion reactor
3) If the first wall and blanket need replacing every n-years due to radiation damage from neutrons then there will be what you call waste. But this ‘waste’ is harmless after 100y unlike fission products. There is far more waste produyed every year by German coal fired stations.
4) Fast breeder reactors are only needed if an expansion of nuclear energy causes the price of uranium to rise. Fusion may be working before then.
You can’t have it both ways. Either global warming is a threat to humanity during the next 100 years or it isn’t. If it is then we need a non-carbon source of energy. If you think renewables will meet the energy needs of say Europe then you are sadly mistaken. Therefore like it or not we will have to expand nuclear energy. It is only a matter of time before the German government backtracks on its decision to phase out nuclear power.
Bindidon, what is your point? Solar and wind energy hardware are made in factories run by fossil fuel. Does that make them illegitimate? Having cheap abundant energy solves many problems, including processing waste.
Also, you did not comment on aneutronic fusion projects. With negligible neutrons, no containment walls, no bulky steam turbine, just direct electronic induction, what’s not to like?
For being one to recognize hype from the good old sixties you should be wise enough by now to realize that every proponent (or opponent) of alternative technologies are full of hype. It might even be conceivable that climate doom is significantly hyped, as was aids, Y2K, Chernobyl cancer, Saddam’s nuclear threat. The internet was over-hyped in 2000 but is slowly realizing its original envisioned potential. The same thing could be said for space exploration.
I am not sure what the lesson in all this is but we should never give up creating visions of a successful future and then do our very best to climb there one rung at a time.
CONTROLLED THERMONUCLEAR FUSION
ANATOLIJ ANDREUS
Controlled thermonuclear fusion.
There is a phenomenology of the nature of electrino and positrino. It is described as a postulate on the structure of an electron and a positron from electrino and positrino. Postulated as absolute symmetry, the tetrahedron-cubic basis of the world – ASTC.
It is necessary to carry out research in the implementation of the creation and maintenance of the environment of free electrino and positrino with a certain energy density per unit volume for the implementation of controlled thermonuclear fusion.
http://vixra.org/abs/1904.0491