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ESG Focus: The Science And Propects of Fusion

ESG Focus | Jun 01 2023

FNArena's dedicated ESG Focus news section zooms in on matters Environmental, Social & Governance (ESG) that are increasingly guiding investors preferences and decisions globally. For more news updates, past and future:

ESG Focus: New Fusion Technologies

For those that really need to understand how their investments work, and with some estimates suggesting a fusion breakthrough as early as 2025, we examine the nuts and bolts of fusion and the latest private sector innovations.

-Fusion breakthrough has world aflutter
-It’s the old E=MC2
-“Limitless” energy may be an exaggeration
-Major challenges
-Start-ups working on new generation of fusion projects

By Sarah Mills

Fusion breakthrough has world aflutter

Last December, the United States government-funded National Ignition Facility announced it had broken fusion ground – generating more energy from the nuclei than was injected via laser. 

A mini media storm ensued.

Unfortunately, it wasn’t really all it was cracked up to be.

Longview Economics pointed out fairly early in the game that the result did not include the energy used to power the lasers, after accounting for which, the process still produced negative energy.

But it did prove that fusion was possible, despite the physics saying it wasn’t. 

It also drew the world’s attention back to the elusive fusion grail and, as it turns out, quite a bit has been happening on the technology front in recent years, leading some in the industry to expect a breakthrough as early as 2025.

In this second article in our two-part series on fusion (the first covered the investment prospect), FNArena provides a rundown on the physics, including the mechanics, of fusion and reports on which technologies have taken pole position.

Just Quickly, How Does Fusion Work

Fusion mechanics revolves around Albert Einstein’s equation of E=mc2, E being energy, m being mass and c being a constant (the universal constant of the speed of light). The squaring reflects the role of kinetic energy when an object is accelerated.

There are plenty of Google articles on this equation; and I can recommend E=mc2 – A Biography Of An Equation – by David Bodanis – an oldie but a goodie for those interested in popular science.

Fusion aims to force a nucleus to become a lighter nucleus, releasing a massive amount of energy in the process – the weight of the lost mass (which in a nucleus is pretty small) times the speed of light, which is nearly 300,000km per second, squared (which is massive). 

The process largely works only with the lightest element in the periodic table – hydrogen.

More specifically, fusion involves pressuring stable hydrogen isotopes, deuterium (a form of hydrogen, found in heavy water and seawater, and twice as heavy as normal hydrogen) and tritium (which is rare and more difficult to handle, and three times as heavy as hydrogen).

The process forces the isotopes to overcome their repulsion and pushes them close enough for the strong nuclear force to unite them and form a new atom (helium, the second-lightest element in the periodic table) that is lighter than the combined weight of the original isotopes. 

Given the new nucleus requires less bind-energy, the surplus energy is released.

It takes a lot of energy to kick-start the process (heat in the region of 15.5m degrees Celsius is required, combined with the pressure of 250bn earth atmospheres) but once going, it is supposedly just a matter of feeding more fuel into the reactor.

Fusion’s heat requirement is fairly easily achieved (today’s maximum easily achievable temperatures are 100m to 150m degrees Celsius). 

The challenge for physicists is managing the pressure build and maintaining the heat, which we discuss below.

Limitless Energy An Exaggeration

Fusion is often referred to as a “limitless” source of energy but this is an exaggeration – it is just an awful lot of energy.

For perspective, about 2.7m tonnes of coal are required to produce the same amount of energy as a fusion reaction.

The amount of energy also depends on the availability of inputs – in this case deuterium and tritium, which must be constantly fed into the process once it is kick-started. As we discuss below, tritium is rare.

The other great thing about fusion is that it would require no restructuring of existing grid and transmission infrastructure. The heat generated would be turned to steam to drive the turbines in existing grids (and newer technologies aim to harness electricity directly from the fusion fields). 

Fusion also entails less risk of accidents than fission and carries less risk of the theft of atomic material.

Fusion Has Several Challenges

The first challenge facing fusion is one of physics.

Managing the heat and pressure required to kickstart a fusion reaction has yet to be achieved, and physicists are battling with the “isotope effect” which, in theory, basically contradicts experimental results and requires powerful computing to overcome. The code has yet to be cracked.

The second challenge is the resilience of the hardware, which must be capable of operating reliably in conditions of extreme heat and pressure, not to mention volatility.

The third major challenge is the availability of tritium.

The fourth is simply cost and scale. 

The construction of the International Thermonuclear Experiment Reactor (ITER), for example, is estimated at US$67bn. The reactor weighs 23,000 tonnes and stands nearly 30m tall and will sit on a 42-hectare platform on a 180 hectare site with auxiliary housing and equipment. The platform is 400m wide and 1km long – the equivalent of 60 soccer fields.

Major steps have been made in addressing these challenges over the past decade, particularly over the past five years.

Starting With The Physics and Mechanical Challenges

While the extreme heats required are easily attainable, creating the pressure and maintaining the process is less so.

As mentioned above, extreme heat and pressure are required to give the atoms the momentum they need to overcome their repulsion – a point called the Columb barrier – allowing them to break free and form helium. 

Once the Columb barrier is breached, it unleashes the strong nuclear force that pulls the former atom’s neutrons and protons together to form the new, larger nucleus. 

The extreme heat and pressure turns the nuclei into a plasma that burns at least six times hotter than the sun, which can be volatile and difficult to contain.

It is critical that the plasma does not hit the side of the reactor’s capsule wall (made of tungsten, which boasts the highest melting temperature of 3,422 degrees Celsius). If so, it cools instantaneously and can potentially damage equipment.

This is called the confinement process.

To confine and manage the plasma, scientists typically use one of two main approaches: inertial confinement using lasers; and magnetic confinement using magnets.

Inertial Confinement and Magnetic Confinement 

Inertial confinement uses high intensity lasers to heat small pellets containing deuterium and tritium and trigger shock and compression reactions that force atoms to collide many times a second.

The aim is to create conditions that match the Lawson criteria by juggling temperature, density and time to prolong the reaction’s length. 

This process creates a value called the triple product, which, if high enough, results in ignition in which the reaction generates enough energy to sustain itself.

The largest operational inertial confinement experiment is in the US National Ignition Facility.

Inertial confinement uses ion or laser beams to shoot into extremely compressed deuterium/tritium fuel pellets at the rate of several times a second, creating steam to power energy turbines. At the moment, scientists can only manage about once every few days because of the resulting stress on the hardware.

Another inertial confinement approach using different nuclei work by firing a projectile into a fuel-rich target rather than aiming lasers at it.

Magnetic confinement uses magnets to control the plasma within magnetic fields to keep it away from the capsule walls while building pressure to compress the plasma to the point of ignition. (Think Goku’s energy balls).

There are three types of magnetic confinement reactors, the first and most widely used is a tokamak, a doughnut shaped reactor; the second is a pincher; and the third being a stellerator. All are old technologies, which have been refined over a period of about 60 years.

Magnetic Confinement The Odds On Favourite

Magnetic confinement is generally considered to be more likely to succeed than inertial confinement. 

ITER is a tokamak reactor and the majority of private-sector start-ups are using the same technology.

Big inroads have been made with tokamak reactors, with reactions now being able to be contained to within 5cm of the side of the fusion capsule (previously 25cm). This has allowed experimenters to double the plasma volume within the initial dimensions.

If this were to be efficiently achieved, the aim of most would be to capture the resulting heat by catching the neurons in an absorptive blanket and then creating steam to drive a turbine to generate electricity.

The main way to generate magnetically confined fusion is through doughnut-shaped tokamak reactors – a hollow torus surrounded by toroidal electromagnetic coils, which contains the plasma, with a solenoid running through the middle.

The idea is the magnets can control the electrically charged plasma, heating it to the point that the nuclei fuse. 

There are other process, including pinching and stellarators, some of which are being investigated by the private sector.

Stellarators like tokamaks, use a toroidal arrangement of magnets, but the design is more complex.

Pinching uses an electric current through the plasma to generate a self-constraining magnetic field.

Both technologies are being revisited with modern approaches as discussed below.

Tritium – More Precious Than Gold?

Tritium is rare and radioactive and is only found in trace amounts in the heavy water used as a coolant in the fission process in nuclear reactors. 

Tritium is an unwanted byproduct of the fission process and is generated when the deuterium in the heavy water encounters traces of lithium during fission. 

It is usually sold as a medical radioisotope for glow-in-the-dark watch displays and emergency signage.

A typical CANDU reactor (the major source of tritium today) produces 130g of tritium a year.

The ITER collaboration estimates a total fuel requirement of 250 kilograms a year will be needed by 2050, half deuterium and half tritium, to run one 1000MW power plant. Times that by the number of fusion power plants needed on the planet and the figure is substantial.

Tritium is also radioactive with a half-life of 12.5 years. 

From a safety and environmental viewpoint, this compares favourably with the half-life of uranium that ranges between 250,000 years and 4.5bn years, depending on the uranium.

But it means that tritium decays more swiftly. 

So rare is tritium that scientists are concerned they will deplete the world’s reserves in the fusion experimentation stage before having a chance to kickstart the process when the time arrives (producing more tritium and enough would take some time, delaying the introduction of the technology).

As a result, scientists are attempting to breed the tritium within the reactor itself by introducing lithium into the hardware – we discuss this below.

At the moment, it is proposed that the reactors will produce the tritium they need by including a lithium isotope in the absorptive blanket which reacts with the deuterium neutrons to generate tritium and an alpha particle.

Tritium breeding has never been tested in a fusion reactor and leakage or maintenance could prove problematic

Hardware, Material and Waste Challenges

One of the main problems with sustaining nuclear fission is simply hardware. 

The process requires engineering material that can withstand fusion conditions for decades, such as extreme heat and neutron damage, and no facility yet exists where materials can be fully tested, although this is the aim of ITER when it starts burning plasma in 2025

Materials are required that can withstand both extreme temperatures and pressure, and which can manage both.

Tungsten casings, absorptive blankets, powerful magnets, computer hardware and powerful lasers are all areas in which innovation is required.

And that innovation is occurring so rapidly that the time a fusion reaction can be sustained is accelerating sharply.

For example, China’s nuclear physicists recently announced in December a record breaking run of 17 minutes from its US$1trn “artificial sun” – triple its previous record which was set in May – a startling rate of progress. 

This follows a record set by the UK-operated Joint European Torus (JET) reactor in June 22 of 5 seconds.

China expects its Experimental Advanced Superconducting Tokomak (EAST) will come online in 2025.

UK-based JET fusion is the central research facility of the European Fusion Programme and claims to be the most successful fusion experiment in the world.

It is currently the only experiment that can operate with the deuterium-tritium fuel mix that “will” be used for commercial fusion power. 

The company says “will” on its website with a certain amount of confidence that suggests they may know something others don’t, given there are efforts to bypass tritium as an input, instead breeding it in the reactor, or using helium instead.

When it comes to inertial confinement, energy would need to be fired into the fuel many times a second, and at the moment, the labs can only manage about one every three days without compromising safety and hardware. 

Super Computers For A Super Problem

There are issues with the confinement process, the main one being the “isotope effect” in which theory basically contradicts experimental results.

Super computers are being used to solve this problem, which drives heat loss and degrades confinement in tokamaks. The computers calculate mass corrections from super light electrons to balance the confinement process. 

Even now, software is used on supercomputers to track the plasma’s behaviour so quickly that it can alter conditions every 100 microseconds to keep the plasma away from the reactor’s walls.

Success on this front would allow the introduction of a commercial version of fusion that could operate continuously, say physicists.

Scientists believe the introduction of quantum computers this decade will help solve these challenges – a quantum solution for a quantum problem perhaps.

Prohibitively Expensive 

Apart from the rarity of tritium, costs are the most obvious obstacle to the fusion prospect.

Science Direct’s modelling of the magnetic confinement route suggests energy costs for early fusion will be greater than US$150MWh even accounting for production learning. This compares with inflated Australian energy prices between roughly US$60 and US$120MWh.

For now, cost challenges include tritium, which costs more than US$30,000 a gram, compared with US$13 a gram for deuterium.

Other expenses include low power availability from pulsed operation, frequent replacement of vessel components and low efficiency power cycles.

Private Fusion Start-Ups

In the past five years, private fusion start-ups have entered the fray promising smaller, more efficient and cheaper technologies.

Commonwealth Fusion Systems or SPARC is generally considered to be the most prospective.

Proponents say it is in the running to be the first experimental device to achieve a burning plasma and self-sustaining fusion reaction without the need for any further input of energy.

The company hopes to complete its US reactor by 2025 and be generating fusion-sourced electricity as early as 2030, bringing forward timelines by as much as decade.

Its ARC reactor is basically a tokamak that uses superconducting magnets that only became commercially available in the past three to five years, long after ITER was designed. 

The reactor is three times smaller in diameter and 60 to 70 times smaller in volume than ITER’s heart, at 6m wide.

It expects to generate at least 10 times, if not 20 times, more energy as is pumped in – and to be more powerful than ITER.

One reactor could generate 250MW to 1000MW of electricity, which compares favourably with current power plants. 

Zap Energy is another interesting player backed by Bill Gates and Shell. The company is using pinching fusion technology, has already created plasma, and is pitching for commercial production by 2030.

The company claims its technology is “incredibly elegant” compared to competing approaches, requiring no superconducting magnets or high-powered lasers, creating an opportunity to develop smaller more scalable systems to accelerate fusion’s rollout to the grid.

Zap uses a Z-pinch, in which a line of plasma carrying an electrical current generates its own magnetic field that pinches plasma (heating and compressing it) to the point that fusion occurs.

It is just a vacuum chamber in which an electric current strips hydrogen gas of electrons, generating high-energy plasma, which is propelled down the chamber before collapsing into a column, which is then shot through a current strong enough to generate the magnetic field that confines and compresses it. 

TypeOne Energy has adopted a stellarator technology, which also uses magnetic confinement, using deuterium and lithium so as to bypass the challenges posed by tritium. 

The company is backed by TDK ventures, Bill Gates’ Breakthrough Energy Ventures and Doral Energy-Tech Ventures.

Type One uses advances in 3D and high temperature superconductor magnets to confine plasma gases along a twisting circular Stellarator S-shape path.

Some describe describe the stellarator as a barber’s pole wrapped around a doughnut. 

Inside the stellarator, the lithium is consumed to breed tritium, creating a typical fusion reaction yielding helium and a neutron.

The company points out only a few hundred kilograms of deuterium and lithium would be needed to power a big city for a year.

Also garnering about US$2.2bn, it hopes to have a demonstration reactor in place by 2025 and results as early 2030s

The company’s website points out that it could extract the lithium from the vast store of used lithium batteries.

Start-ups Helion and TAE Technologies are coming to the market with a tokamak-based technology offering a twist on the old models.

Their reaction chambers resemble hollow barbells but with their weight in the middle. The ends generate spinning plasma toroids that are fired at each other by magnetic fields, again requiring sophisticated computers to control the process. 

Proponents say they slam together two smoke rings of hydrogen at speeds of a million miles per hours to generate a spinning plasma, which is heated and stablised with particle accelerator beams in a 25m long reactor (again small by ITER standards)

Helion aims to start with a light isotope of helium (instead of hydrogen) but instead of fusing two of these, as happens in the sun, it fuses them one at a time with deuterium nuclei to produce helium and a proton. 

TAE (initially standing for Tri-Alpha Energy) Technologies also takes a different elemental tack. It fuses normal hydrogen and boron (both plentiful) to create three alpha particles but requires massive heat generation. It has managed to glean $1.2bn in funding. 

Helion is also developing an alternative route to electricity generation. Rather than using steam to drive a turbine, the company plans to extract electricity directly from the interaction between the magnetic field of the merged plasma toroids and the external field.

The company appears to be a long way from achieving this, and is said to be trialling different approaches.

General Fusion is adopting a process called magnetized target fusion or inertial fusion, that uses a hydraulic design to apply a shock to the plasma from different directions, causing the fuel to implode and ignite.

It uses a rotating cylinder of liquid metal (lithium in the prototype) as a lining in the wall of the reaction capsule (the proposed commercial model uses a mix of lithium and lead).

Once the fuel is injected into the cavity inside the cylinder, pneumatic pistons are designed to push the metal inward, collapsing the cavity into a small sphere which compresses the plasma to the point where fusion occurs.

If ignition is achieved, the heat (neutrons) should be absorbed by the liquid lithium, creating steam while also converting some of the lithium into tritium for re-use, allowing it to be self-sustaining.

The reactor uses nifty software to control the process but the company believes the removal of electromagnets has simplified the design and removed complexity that might increase the instance of failure.

NearStar Fusions also uses pinching technology and has adopted a pulsed approached called Hypervelocity Gradient Fusion.

This involves combining imploding metallic lines (in a Z machine), with a repeatable theta pinch process developed under a NASA innovative advanced concept study.

Start-up First Light adopts a slightly different approach, wherein the fusion capsule (or reactor) is placed inside a cube shaped amplifier, which boosts the impact of shock waves hitting the plasma within the reactor. 

Start-up HB11 is an Australian company that has adopted a non-thermal fusion fusion technology, which, like Helion, it believes can generate electricity without using steam 

HB11 uses hydrogen and boron elements, and lasers, bypassing the use of the rare and radioactive tritium.

Other Innovations

Most of these technologies are relying on improvements in magnets which can do the work, reducing the energy input into the process.

However, some start-ups are persisting with laser technologies, where one of the latest innovations has been to fire frozen fuel pellets deeper into the plasma where they will burn more efficiently.

Also on the drawing board are micro-fusion reactors for distributed energy mobility. One Israeli start-up is designing container-sized reactors. 

As another example of innovation, last year an exhaust system called the Super-X Divertor was developed that manages the enormous amounts of waste heat produced from a fission reaction.

It basically traps the helium using a magnetic field and diverts it on a longer path until it is cool enough not to damage the reactor’s walls.

High temperature superconducting technology is another area of innovation. 

Innovations in magnet materials have generated huge advances in superconducting magnets in recent years.

One start-up is work on a VIPER cable using yttrium and barium copper oxide which provide less resistance to the flow of electricity than conventional copper lines, with five times as much electric current.

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