Fusion energy is attracting private investment on the billion-dollar scale for the first time in history. James Rice explains how a brighter future could be just around the corner. 

Comment: Harnessing the power of fusion energy has been a tantalising yet unattainable goal for more than 70 years. But recent developments mean it may soon make up a large amount of renewable energy production and become the cornerstone of a carbonless future.

Work being done by New Zealand researchers could help pave the way and finally make fusion reactors economically viable.

Fusion v fission

Fusion energy promises a cleaner alternative to power produced by nuclear fission (splitting atoms to release enormous amounts of energy).

Fusion energy doesn’t use uranium and no radioactive by-products are created. Instead, two atoms of hydrogen are superheated and fused to create a heavier atom – helium – in the same process that fuels our sun.

These fusion reactions release large amounts of energy, though require huge pressures and temperatures to achieve – far beyond what any solid material can withstand. The optimal temperature? About 175 million degrees Celsius.

Despite the high temperatures, so little gas is in the fusion reactor at any given time that if something goes wrong, the heat is quickly dissipated to the reactor wall causing little structural damage.

Overcoming the plasma problem

At the required temperatures, gas in the reactor becomes ionised and forms plasma – the hot matter that generates huge amounts of energy. One way to contain the plasma is by using exceedingly strong magnetic fields in a device called a tokamak.

Dozens of experimental tokamaks have been built around the world to test the physics involved. Many use ordinary copper magnets in short pulses, but others use superconducting magnets to sustain longer experiments. Massive electric currents must be run through these superconducting magnets to produce the required magnetic field.

And herein lies the problem.

Typically, these magnets require giant power supplies, making them costly and inefficient to run, and limiting the net power possible from the reactor. To date, even the best attempts have fallen just short of the output required to create an economic source of power.

High-temperature superconductors (HTS) are about to change all that.

HTS systems are being developed by Paihau—Robinson Research Institute at Te Herenga Waka—Victoria University of Wellington. These systems will enable more compact fusion reactor designs that are cheaper to build.

Fusion power from a reactor scales exponentially with the strength of the magnetic field used. HTS magnets can sustain much stronger fields than their low-temperature predecessors. Such magnets are key to making fusion economically feasible. Stronger fields mean smaller reactors and lower costs.

Paihau—Robinson researchers are developing a HTS power supply called a flux pump, which can generate and sustain the multiple thousands of amps needed in a magnet for the very large magnetic fields that fusion requires. The Institute’s researchers have been at the forefront of HTS flux pump development for the past decade.

The flux pump is novel in that it can use wireless power transfer, so does not need to be directly connected to the magnet. This helps reduce the required cooling power and can enable HTS magnets to remain energised for longer than older superconducting magnets.

Billion-dollar investment

On the back of recent research, fusion is attracting private investment on the billion-dollar scale for the first time in history.

In January, Commonwealth Fusion Systems (CFS) in Boston, Massachusetts, announced a huge US$1.8 billion of private funding to develop a commercially viable fusion reactor.

Last year, CFS successfully tested the most powerful high-temperature superconducting magnet ever made for fusion research, generating a staggering 20-Tesla of magnetic field (Tesla is a unit of magnetic field intensity, as well as a car).

The funding announcement followed two other international breakthroughs in the past six months.

In December, the Joint European Torus (or JET), based in the UK, was able to generate 59 megajoules of fusion energy for five seconds. This may not seem like a major advance, but the previous record of 20 megajoules was set 25 years ago in 1997.

Meanwhile, researchers at the Experimental Advanced Superconducting Tokamak (EAST) in Hefei, China, ran their experiment at 70 million degrees Celsius for just over 1000 seconds – another world record.

Through the UK Atomic Energy Authority’s STEP programme, the UK government is already aiming to put fusion power into the UK grid by 2040. A brighter future is just around the corner.

James Rice is a PhD candidate at the Paihau — Robinson Research Institute at Te Herenga Waka - Victoria University of Wellington. His PhD is supported by funding from the UK Atomic Energy Authority'...

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