A long, long time ago the promise emerged that we would eventually tame processes active in the sun - the fusion of hydrogen to helium - to provide all our energy needs. The challenge of the task turned out to be formidable, but slowly fusion energy is clawing its way back into the news.
Since 2016, Australia is participating as a non-member country in the groundbreaking construction of the world's largest tokamak fusion reactor in France*.
It is a multi-national effort, with thirty-five member countries contributing to the ITER project, which aims to prove that fusion power can be sustainably produced on a commercial scale.
The potential of the technology is indeed staggering: power generation at a comparable cost to a fossil fuel or nuclear fission plant with none of the environmental costs associated with radioactive waste disposal or CO2 emissions.
A tokamak reactor is one of several potential concepts to sustain a plasma of hydrogen that is hot enough for a thermonuclear fusion to occur, with the potential that excess energy can then be harnessed as a carbon-free source of power.
In a vacuum chamber extreme heat and pressure converts hydgrogen into an electrically charged gas, while the generated ions are then kept away from the chamber walls using a magnetic field.
The first experimental tokamak was built in the US in the 80s, but was then shut down in 1997, never achieving the goal of producing more energy than had to be put in from outside to keep the plasma hot enough.
But time has moved on. And ITER, labelled the most complex science project in human history is now to 50% on the way.
It is scheduled to have completed the first stage of operation as a functional machine by 2025, and if successful may come on line by 2040 to then produce 500 megawatts of thermal power.
Recently ITER reported the completion of ground insulation for the first of seven central solenoid production modules in the US and that the first toroidal field coil passed all fitting tests in Japan - it means that two important milestones have now been achieved.
But not all is well with the funding of the project which is estimated to cost US$22 billion. Under President Donald Trump the US is scaling back its support for fusion research, and is contemplating to pull out from the ITER project altogether. This sparked a warning by the National Academies of Sciences, Engineering, and Medicine that the US was at risk to be left behind in the pursuit of emissions-free energy
*Australia's contribution is coordinated by the Australian ITER Forum, involving six universities - the Universities of Sydney, Newcastle and Wollongong, the Australian National University, Curtin University of Technology, Macquarie University - and ANSTO.