According to a Technology Review story, a Canadian start-up company, General Fusion, is building on two decade-old research and advances in digital processing, using a fusion approach that is based on 220 pneumatic pistons simultaneously ramming a metal sphere containing lead-lithium liquid and injected plasma targets composed of deuterium and tritium.
By spinning the liquid metal, a vortex is created in the middle. A target is injected from each end of the vortex, which collide and create a single plasma ring.
The idea is that the pistons create a shock wave that travels through the lead-lithium towards the target. The hydrogen isotopes would then be fused into helium. The resultant neutron-driven heat energy would be captured from the lead-lithium by a heat exchanger. Part of the heat would be used to generate steam to power a turbine, and part would be used to reset the pistons. The process would be repeated each second.
The neutron production in fusion systems always generates concerns about radiation and mechanical damage, but General Fusion’s website claims they have that covered. “Because the fusion plasma is totally enclosed in the liquid metal, the neutron flux at the reactor wall is very low. Other fusion schemes struggle with a high neutron flux at the wall that rapidly damages the machine and also produces some radioactive material. General Fusion’s innovative use of the liquid metal wall provides a simultaneous solution of the multiple technical constraints needed to make fusion energy production a practical reality,” the company asserts.
This is quite a different approach than that being pursued by other more well-known efforts, such as the international ITER project, that use superconducting magnets or lasers to manipulate the plasma.
According to the story, if all goes well over the next five years – which requires both positive results from fundraising and prototypes – General Fusion will try to build a 100 megawatt unit. The company estimates the cost of this utility-scale system to be $500 million.
The technology behind General Fusion’s approach is being taken seriously. The general science was first identified at the United States Naval Research Lab. The idea of using rams to generate the shockwave was developed by General Atomic, but the computational power to control a network of pistons was unavailable in the 1980s.
General Fusion thinks it can get a prototype reactor operating for $50 million.