Is fusion moving closer?

Image: ITER (Photo credit: ITER Organization/ EJF Riche)

AFTER MORE THAN THREE DECADES in development, is nuclear fusion technology ready to start delivering on its promises? Advancements have recently been coming thick and fast, and it is becoming clear that the next five to ten years are going to be critical.

An analysis of global patent filing activity linked to nuclear fusion between 2011 and 2020 reveals that the volume of international patent families (IPFs) filed at the World Intellectual Property Office (WIPO) peaked in 2018. The drop-off in subsequent years may be due to incomplete data caused by the 18-month delay in new applications becoming public.

Examination of innovation activity in the top five jurisdictions reveals that filing activity in both China and the US peaked – in 2019 and 2017, respectively. While patent filing activity in other key territories, such as Japan and Germany, is at a significantly lower level and shows a slight decline over the same period, the overall picture suggests that research science in this area is gathering momentum as the prospect of large-scale nuclear fusion power generation nears.

Growing optimism

After many years of slow progress for the leading R&D projects, news that the MAST Upgrade experiment at the UK’s Culham Centre for Fusion Energy achieved its first plasma in November last year, has contributed to a growing sense of optimism that nuclear fusion power generation is now tantalisingly close.

As part of its net zero carbon emissions by 2050 goal, the UK government has also announced that it is looking for a 100 hectare site to build the world’s first prototype nuclear fusion power plant, and hopes to start construction by 2030. The Spherical Tokamak for Energy Production (STEP) project, as it is known, is being overseen by the UK Atomic Energy Authority (UKAEA), and aims to have an operational facility by 2040.

For the past three decades or more, the main barrier to nuclear fusion power generation has been achieving ‘fusion ignition’ – the point at which nuclear fusion energy becomes self-sustaining. After more than sixty different prototypes have been developed globally there is still little consensus on the best way of sustaining plasma in order to facilitate ignition and sustain combustion.

The International Thermonuclear Experimental Reactor (ITER) in southern France seems to be leading the way, with machine assembly works already underway. This will be the world’s largest tokamak nuclear fusion reactor, and capable of producing more power than it consumes. When its first plasma experiments begin in 2025, it will use 50MW of injected heat to produce 500MW of fusion power for long pulses of 400 to 600 seconds. Deuterium–tritium fusion experiments will follow by 2035.

In contrast, the UK’s STEP project is on a much smaller scale, and is aiming for a net energy gain of 100MW.

Much of the progress with ‘fusion ignition’ has come from laboratory experiments focused on reaching the extraordinarily high pressures and temperatures required to achieve fusion. To do this in a laboratory, a fuel containing two of the heaviest hydrogen isotopes, deuterium and tritium must first ignite. This requires a temperature of 150 million degrees Celsius — much hotter than the sun. Achieving fusion ignition in this way has been incredibly challenging, and advanced at a very slow pace.

But several government-backed, multi-disciplinary experiments, including ITER, the MAST Upgrade and National Ignition Facility (NIF) in California, are now nearing a solution at more or less the same time.

Generating excitement

Despite its relatively small scale, the UK’s MAST Upgrade is among generating excitement as it continues to explore compact fusion plants.

Based on the original Mega Amp Spherical Tokamak (MAST), which ran from 2000 to 2013, the upgrade has several performance-enhancing refinements, including an innovative plasma exhaust system.

Recent patent applications focus on the development of divertors, such as the Super X divertor, as part of the exhaust system for reducing heat and power loads from particles exiting the plasma. The MAST Upgrade is the first tokamak to trial the Super X divertor.

Similar compact nuclear fusion research projects are underway in the US, including the construction of a reactor called Sparc, run by the Massachusetts Institute of Technology and Commonwealth Fusion Systems, which is expected to get underway in 2021 and is hoping to complete within just three to four years.

With confidence high around fusion itself, innovators are competing on other lines of research. They include developing advanced materials that can withstand extreme heat and pressure for the long periods required by commercial plants; and novel methods of cleaning and maintaining the reactors.

For example, recent patent applications are directed towards the development of plasma-facing materials for nuclear fusion reactors. Innovation activity has focused on the composition, structure and manufacturing process for plasma-facing materials. With respect to the novel methods of cleaning the fusion reactors, there have been patent applications directed to, for example, methods and systems for remote maintenance and for electrostatic dust detection and removal in reactors.

Significant innovation needed

In other recent developments, laser confinement technology has emerged as a potential alternative to the tokamak-style nuclear fusion reactor.

Instead of using powerful magnetic fields to confine the plasma, this technology uses laser pulses to compress the reaction around a small pellet of feedstock material. It could provide a much more compact power generation device, opening up uses in many more potential applications. However, like tokomak systems, significant innovation is still required before commercial laser confinement systems can be produced. In particular, further development to produce sufficiently powerful and efficient lasers is needed before commercial application is likely.

The complex, multi-disciplinary nature of many of the experiments targeted towards early stages of fusion development, as well as the size of the construction projects required to make these experiments, means that progress has been slow. Patent applications for this technology have not yet approached the numbers we see being filed for other power generation technologies. But patent protection has been secured for some key technological building blocks, and we would expect the volume of patent filings to increase as we approach commercial scale, both for the key technologies needed to generate fusion and for all of the supporting technology needed to sustain it and use surplus power from the reaction.

Much of the intellectual property value of the current global nuclear fusion experiments is shared by many different parties through joint ownership and development agreements. However, as the innovation focus moves to other areas of R&D, such as materials and cleaning systems, patents are likely to be more important. At this stage, some of the innovators in these collaborations are likely to seek patent protection independently, to commercialise their technologies as widely as possible.

Such patent protection could help to secure market share in the nuclear fusion power industry of the future. It could also open the door to other market opportunities where technologies with similar high-performance attributes could bring commercial benefits.

Ripple effect

In the same way that NASA’s investments have inspired innovation, with economic benefits around the world, government-led investment in nuclear fusion could have a similar effect.

Author details: Andrew Thompson, Partner and cleantech sector specialist at European intellectual property firm, Withers & Rogers