- Title: New exhaust system brings fusion energy one step closer
- Date: 1st December 2018
- Summary: VARIOUS OF CONTROL ROOM / STAFF
- Embargoed: 15th December 2018 09:19
- Keywords: fusion nuclear fusion climate change global warming NASA tokomak UKAEA nuclear
- Location: CULHAM, ENGLAND, UK / IN SPACE
- City: CULHAM, ENGLAND, UK / IN SPACE
- Country: United Kingdom
- Topics: Science
- Reuters ID: LVA0079943BDN
- Aspect Ratio: 16:9
- Story Text:Researchers attempting to commercialise nuclear fusion believe they could have solved one of the most pressing problems in generating the energy that powers the stars; how to exhaust gas at temperatures hotter than our sun.
Fusion is the nuclear reaction permanently taking place in the sun, but to reproduce it on earth requires creating a hot gas known as a plasma ten times hotter than the sun, at 100 million degrees Celsius.
Now researchers trying to devise a smaller, cheaper fusion reactor say they are just months away from testing a plasma exhaust system that can cope with extreme temperatures akin to those faced by a spacecraft re-entering the atmosphere.
The UK Atomic Energy Authority (UKAEA) has spent £52 million ($68 million) building its Mega Amp Spherical Tokamak Upgrade (MAST-U) facility in Oxfordshire to help resolve key plasma physics issues.
"In principle you can build a more compact machine but the boundary condition doesn't change. You still need the middle to be hotter than the sun. So if you put that into a much smaller box the chances of melting the box are therefore much higher. So you have to have a really clever way of getting the heat out of the device," Professor Ian Chapman, Chief Executive of the UKAEA told Reuters.
The system involves a sacrificial wall that will require changing every few years while also lengthening the path travelled by the gas to allow it to cool more before it comes into contact with the wall.
"The hot bit in the middle is about a hundred million degrees. 100 million degrees, ten times hotter than the sun. As it moves along that path it cools down a lot so that by the time it gets to the wall it's only a few thousand degrees. So that the wall will melt at a few thousand degrees. So already it's cooled down enormously. In the upgraded machine we're hoping to cool it down even further so that we can take an even hotter source in the middle," Chapman said.
The new reactor, or tokamak, also breaks the mould by changing from a torus or doughnut shape to a sphere, giving better performance at a smaller size.
"We're here to commercialise fusion power," Chapman said. "Fusion offers this enormous potential, there's no long-lived radioactive waste, it's effectively inexhaustible fuel, there's no carbon emission. It sounds perfect but it's really hard to do. But we know it works."
Fusion energy is released as a neutron when two hydrogen isotopes merge to create helium. In the Sun, huge forces of gravity help this happen but on earth temperatures hotter than the sun are needed to create the reaction, requiring enormous amounts of energy.
An international fusion project, called ITER, is designed to achieve the first energy gain from fusion, releasing ten times the power put in, is scheduled to begin operation in France in 2025.
"It happens in all of our stars and we've done it here on Earth. JET (Joint European Torus) has produced 16 megawatts of fusion power. It doesn't work on a commercial basis. It doesn't work on the scale that we need it to build working reactors. That's what ITER will prove, that we demonstrate fusion on a commercial scale - 500 megawatts is commercial scale - and then it all becomes about market dynamics is the capital cost and electricity cost competitive?" Chapman said.
Researchers around the world are working on fusion to provide a long-term answer to our energy needs without causing global warming.
"The joke in fusion is always that fusion is 30 years away. Everybody's heard this joke...but fusion is happening. Seven years from now we will deliver ITER. It will be functional. And that's seven years till fusion really entering what I call the delivery era," Chapman said.
The challenges of replicating the fusion process on earth are enormous and critics say it remains unclear whether the technology will ever be commercially viable.
Next week the Polish city of Katowice hosts the 24th Conference of the Parties to the United Nations Framework Convention on Climate Change (COP24), attended by world governments.
COP24 takes place from December 2-14. Its 2015 precursor COP21 in Paris saw parties reach a landmark agreement. The Paris Agreement's central aim was to commit countries to keeping global temperature rises to 1.5 degrees Celsius. - Copyright Holder: FILE REUTERS (CAN SELL)
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