A Canadian company, General Fusion, claims that it can build a relatively low-tech prototype nuclear fusion power plant within the next decade for less than a billion dollars.

For decades, billions of dollars have been spent on research into ways of building a practical fusion reactor for electricity production. The major problem is creating a controllable fusion reaction that gives off more energy than is needed to trigger it and most scientists believe that achieving this will take several more decades and cost tens billions of dollars.

General Fusion’s approach involves building a metal sphere about three metres in diameter filled with a liquid lead-lithium mixture. This liquid is spun to open up a vertical cylindrical cavity in the center of the sphere. Two magnetized plasma rings composed of deuterium-tritium fuel are then injected into each end of the cavity and merge in the centre.

The outside of the sphere is covered with pneumatic rams, which use compressed gas to accelerate pistons. These pistons simultaneously trigger a high-pressure spherical compression wave into the liquid metal. When the shock wave arrives in the center, it rapidly collapses the cavity with the plasma in it – briefly creating the conditions for fusion.

The fusion reaction releases energy in fast neutrons. The neutrons are slowed down by the liquid metal causing it to heat up. A heat exchanger transfers that heat to a standard steam cycle turbo-alternator to produce electricity for the grid. Some of the steam is used to power the rams.

Global Fusion say their approach of using mechanical brute force from low-tech pneumatic rams, rather than expensive high-power pulsed electrical or laser systems, reduces the cost of the energy delivered to the plasma by a factor of 10. This would make such a nuclear fusion power plant commercially competitive against the cheapest fossil fuel.

General Fusion has completed construction of a small demonstration system. The company expects that the next phase, a working prototype, will take another four years and that a demonstration plant dleivering 100 megawatts to the grid could be in production within a decade at a cost of around $US500 million.