Doing Fusion A Little Differently
There are various ways to approach the problem of nuclear fusion power. General Fusion is one company trying this on a smaller scale. Michel Laberge, the CSO and founder of General Fusion, spoke to Dave Ansell about what they are trying to achieve...
Michel - We are doing something called magnetised target fusion. Have you heard before in the show, fusion is usually done of two way. There's the Tokamak and then there's the inertial confinement fusion. In the Tokamak, the plasma is very, very thin, not very dense at all. There's a magnetic field that keeps it from preventing to get the heat to escape. In the inertial confinement fusion, they compress the plasma and there's no magnetic field. So, the heat can escape very fast, but because they compress it very fast, they can try to beat that. we want to be somewhere in the middle. We want to be an intermediate amount of density. And we want the magnetic field. So, we produce the plasma with some magnetic field and we compress it. We can compress it slower than the laser guy because we have magnetic field, so it's going to be much easier to compress it. And we don't need so much confinement as the Tokamak guy because we don't want the plasma to exist for very, very long. We want to compress it relatively fast.
Dave - So, what is the machine you're building doing? What does it look like?
Michel - So first, we need to produce a plasma with a magnetic field and for that, we use something called a spheromak generator generator - that's a nice name. This uses a couple of capacitors and we make a huge electric discharge into a gas and that produces the plasma. In that plasma, there's electrical current which make the magnetic field. We don't use external magnet. All the magnetic field that hold the plasma together is produced by the current that's in the plasma itself and that's called a spheromak. So, we put that in the middle of a large sphere which is fill of liquid metal. The liquid metal is spinning and because it's spinning, it opens holes in the centre - a bit like in your toilet or something. We inject the plasma inside the hole and then we run pneumatic piston all around the machine and that compresses the liquid metal and it compresses the plasma, and the plasma will heat up to thermonuclear condition. It will emit neutrons. The neutron will be absorbed by the liquid metal and it will make it hotter and then we will pump that out, make a heat exchange to make some steam, and the steam will run the turbine to make the electricity.
Dave - So, that all sounds very nice and simple in theory. How close are you getting it to work?
Michel - Okay. So right now, what we're doing is we're making the plasma successfully - the initial plasma before the compression. So, it took us a few years to achieve that, but now, we can produce that. Today, we're making some compression experiment. You see, when we compress the plasma, if it does indeed goes to a thermonuclear condition. Right now, we have some little issues with that, it is not quite working. The plasma goes unstable and cool off. So hopefully, we will manage to fix this problem in the next couple of years or let's say in 2 years. And those are one of single compression experiments, it is not done with a power plant system. After those 2 years, we hope to build a prototype plant that will run at a relatively low repetition rate. Like in those pulse systems, you have to show that every second or so to make some energy, this machine would be slower than that and that would probably take about 3 years. If that's successful then we will build a real power plant, something that make electricity on the grid, and that would take another 5 years after that. so, if you add 2 plus 3, plus 5, we're thinking about putting electricity on the grid in gain of 10 years.
Dave - Nuclear fusion always seems to be more difficult than people think it's going to be. Are you expecting that?
Michel - Yes. Well, most people think it is very difficult. The thing is that the way we are trying to achieve fusion, that General Fusion is quite different than the normal Tokamak and laser. So, the Tokamak and laser, they've been active for many years. They understand the problem and they know it's difficult and they will probably succeed, but it's a difficult task. Here, we have something new. Now, it could be worst, it could be better, at this point, we don't really know because this is kind of new. But I'm hoping that it'll be easier than the two different approaches that are usually used and therefore, we can succeed with less trouble.