Many roads lead to Fusion power

I saw a programme last night with James May talking about ‘alternative’ (his quotes) energy, and there was the usual ones of solar, wave power (I remember the Salter Duck from a while back, but didn’t realise it was government incompetence that killed it off – basically they said it would be 10 times more expensive than nuclear, and that did it in), kite power from the Netherlands and some guys in the States cracking CO2 to create petrol using concentrated sunshine.

So far, so so-so.

Then there was the bit about Nuclear Fusion – the sun uses it, it’s clean, it only creates helium, enough fuel to power the planet essentially forever, and all you need is … 100 million degrees to fuse the atoms of hydrogen together. Cue; CERN, ITER, JET, big computers, sirens, and tokamaks (toroids – doughnuts). Then – some very nice footage of James looking at a screen that’s showing some actual fusion going off in a the toroid – sexaay!

Except there’s a lot more to fusion than the tokamaks….

There’s more than one way to do it

One major problem the tokamak guys have had is that the plasma must not touch any part of the containment vessel (or it will melt – 100×106 degrees is not to be sniffed at). So they use magnetic fields to prevent this from happening. This is, as they say in physics, non-trivial (this is a short-hand for saying it’s bloody hard).

But there’s more; these plasmas have (to a first approximation) a Maxwellian distribution of energy, which basically means that although you might want the hydrogen atoms to bash around at 100 million degrees, there will be atoms hurtling around at 200 million degrees (although not very many of them, and it’s not necessarily a good thing if they are) and other atoms moving at 10 million degrees (still a good clip, but they’re not going to help matters if what you’re after is fusion). You can’t get away from this if you’re using thermal energy (heat) to fuse the atoms together.

Fusion in the form of tokamaks has always been ’40 years from commercialisation’, and some of the quotes regarding tokamaks are scathing, e.g. “Nuclear fusion powers the stars, and they don’t look toroidal!” – Dr. R Bussard (more on him later)

So what other options are there?

There’s cold fusion, which you’ve probably heard of. The physics behind this is still a little shaky, but there does seem to be something there – recent experiments are getting coverage and seem to be repeatable, which is always a good thing.

However, in my opinion there are at least two dark horses out there that may well steal the show, firstly ‘focus fusion’

Focus Fusion – or dense plasma fusion

The Focus Fusion Society has a wide range of resources, including graphics, animations and videos of focus fusion, so please spend a few hours there – it’s definitely worth it.

I first came across focus fusion through the google video techtalk and was struck by how the system depended on instabilities as the plasma evolved over time.

The energy you would get out of a focus fusion reactor would be electrical – no intermediate water turbines, molten sodium and other heat-exchange complications. This is a good thing.

IEC fusion – Polywell and Dr Bussard

The second area of fusion research I have been following is that of Inertial Electrostatic Confinement (IEC) fusion, in the form of the Polywell device from EMC2. This is a device that was invented by Dr. Robert Bussard, who also invented the Bussard Interstellar Ramjet, which has been used in stories by Larry Niven and others.

Please check out his talk at Google about the Polywell device, the full talk is 90 mins, but this 3 minute snippet goes a little into the economics that would come into play should these device be viable and mass-produced.

Essentially, the Polywell device (which looks so like a 50’s Sci-Fi prop!) accelerates magnetically contained electrons into a central area which then enables the fusion of Boron and Hydrogen to take place. You then end up with charged particles – ie electricity. One aspect of the Polywell is that variants of it can be used to ‘burn up’ nuclear waste – see the 3 minute video for details.

Some facts about the Polywell;

  • This is a non-thermal device – you would take electricity directly from it
  • It is relatively small 1-5m (not the cathedral size tokamaks)
  • There is no neutron radition – none. The system uses a Boron-11 reaction (00:05:04 into the video), which fuses with a proton to give excited C12, which decays into He4 and Be6. As Dr Bussard says (00:05:37) “This is the only nuclear energy-releasing process in the whole world that releases fusion energy as 3 Helium atoms and no neutrons”

I don’t think ITER, JET and CERN are going to come up with any usable energy from fusion anytime soon – they’ve been at it for almost 60 years and still haven’t got positive net energy (more energy in than they use to run the machines up).

These other methods may not do it either, but if ever there was a David and Goliath moment being set up – then this is it.

The next ten years will be very interesting – we’ll either know these methods (or others) work, and will start churning out these reactors by the shipload, or they won’t and we’ll find something else to try. Something tells me the tokamak guys will still be talking about tweaking some plasma constant, or bickering over where the location of the HQ for phase ‘n’ of the project.

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