The biggest science experiment on Earth could avert climate change. But is there still time for nuclear fusion to work?
LONDON, 29 July, 2020 – Nuclear fusion is the most ambitious project in the world, recreating on Earth the complex heat-producing reactions of the sun in the hope of making unlimited carbon-free electric power.
The world’s first fusion machine, ITER, under construction in Provence in southern France, is extraordinary as well because it is a collaboration between the scientists, engineers and politicians of the planet’s 35 richest and most powerful countries – states that on other matters frequently disagree.
But the potential prize of harnessing the power of the sun on our own planet to make unlimited electricity is enough to make all these nations bury their differences and combine to share their secrets and their engineering skills in the hope that all will benefit from this potential energy bonanza.
28 July was chosen as the day to celebrate the start of the assembly of ITER, a machine that will be the prototype for a generation of much larger successors on the road to possible commercially viable nuclear fusion. They, it is hoped, will signal the end of the use of fossil fuels and save the world from the worst of climate change.
“Enabling the exclusive use of clean energy will be a miracle for our planet”
French President Emmanuel Macron and leaders from the European Union countries and China, India, Japan, Korea, Russia, and the United States met virtually on 28 July to declare the start of a new energy era. Each of the 35 countries has made some components and helped to pay part of the costs of ITER, the world’s largest science project.
Its total cost is unknown, since countries are paying their share in kind by producing one-of-a-kind engineering feats like giant magnets weighing many tonnes, to tolerances of two millimetres, some of them with the precision of a Swiss watch.
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Fusion: how it works
- A few grams of deuterium and tritium (hydrogen) gas are injected into a huge, donut-shaped chamber, called a Tokamak.
- The hydrogen is heated until it becomes a cloud-like ionized plasma.
- The ionized plasma is shaped and controlled by 10,000 tons of superconducting magnets.
- Fusion occurs when the plasma reaches 150 million degrees Celsius—ten times hotter than the core of the Sun.
- In the fusion reaction, a tiny amount of mass is converted to a huge amount of energy (E=mc2).
- The ultra-high-energy neutrons from fusion escape the magnetic cage and transmit energy as heat.
- Water circulating in the walls of the Tokamak absorbs the escaped heat and makes steam. In a commercial plant, a steam turbine will generate electricity.
- Hundreds of Tokamaks have been built; but ITER will be the first to achieve a “burning” or self-heating plasma.
– By ITER
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To get some idea of its complexity, ITER uses three closely integrated types of magnets to contain, control, shape, and pulse the plasma it holds – at 150°C million.
But if the prototype could be made to work, then the idea would be to build other versions with a slightly increased size of plasma chamber. Each of these machines would then produce a staggering 2,000 megawatts, enough for more than two million homes.
Reliability testing
Bernard Bigot, director-general of ITER, hopes that construction will be finished by December 2025 and the scientists and engineers on site will then launch “First Plasma,” the initial event to demonstrate that the machine actually works and can generate electricity.
The question then will be to step up trials to see whether ITER can be made to work consistently and reliably. Then, if successful, the consortium of nations needs to decide whether it can be scaled up – and how long it will take to build other machines, this time large enough to make a difference to climate change.
It is a difficult and as yet unanswered question. On the plus side, fusion in theory provides clean, reliable energy without carbon emissions. It is said to be safe, with minute amounts of fuel and no physical possibility of a runaway accident through a meltdown.
The fuel for fusion is found in seawater and lithium. It is abundant enough to supply humanity for millions of years. A pineapple-sized amount of this fuel is the equivalent in energy terms of 10,000 tonnes of coal.
Ready by 2045?
On the minus side, though, fusion has been around as a concept since the 1950s. It has taken 14 years of international effort to get to this stage of the project – and it will be another four before it can be powered up. It will probably take at least 20 years or so more, even if it works as hoped, for a full-scale fusion machine to be built and commissioned.
Dr Bigot says: “If fusion power becomes universal in complement to renewable energies, the use of electricity could be expanded greatly, to reduce the greenhouse gas emissions from transportation, buildings and industry.
“Enabling the exclusive use of clean energy will be a miracle for our planet.”
But with the planet already heating at an unprecedented rate and the danger threshold of temperatures of 1.5°C above pre-industrial levels already close, there may not be enough time left for the fusion dream to be realised. – Climate News Network
