Nuclear fusion is touted by many as a future saviour of humankind, potentially offering us a renewable, efficient and clean source of energy. These voices have only intensified in recent years as laboratories appear near to demonstrating that a viable fusion energy is possible. But how true are these claims? And can it really help save us from impending climate disaster?
Nuclear fusion: the basics
Nuclear fusion is a physical process where lighter elements are combined together to form heavier ones. The phenomenon creates enormous amounts of energy, but requires extreme amounts of heat and pressure to get started – so extreme in fact, the only place fusion is observed naturally is within the stars themselves.
In our Sun, the gargantuan quantities of heat and pressure created by its powerful gravity drives together hydrogen nuclei, concurrently adding protons as the nuclei become heavier versions of hydrogen (known as isotopes).
The process progresses through two heavier versions of hydrogen: deuterium (with one proton and one neutron) and tritium (one proton and two neutrons), until creating the next element on the periodic table, helium (two protons, two neutrons) – alongside a healthy serving of heat energy.
The process of nuclear fusion is self-sustaining as long as there’s hydrogen to fuse, and keeps most of the stars burning bright in the sky.
It’s not hard to understand, therefore, why scientists are so keen to exploit this process on Earth. Since the 1940s, fusion researchers have attempted to harness the power of these star-forges, and create a fusion reactor here on Earth in the hopes of providing endless, renewable, zero-carbon energy.
Recreating a star on Earth
“Fusion is always 30 years away”, the old adage goes.
It’s indisputable that a functional nuclear fusion reactor would be transformative to humanity. A litre of fusion fuel is equivalent to 55,000 barrels of oil and only requires hydrogen – the most common element in the universe.
Recreating the insides of a star is no easy feat, however. And channelling this into a usable energy source is even trickier.
As it stands, there are two main methods being pursued for simulating such conditions.
The first is known as inertial confinement. This is where lasers are used to heat and pressurise small pellets of fuel, generally containing the hydrogen isotopes, deuterium and tritium. Lasers blast the outside of the fuel, which explodes outwards and compresses the centre of fuel pellet, accelerating it inwards and building up massive heat and pressure until, eventually, it triggers a fusion reaction and creates helium.
The other method is called magnetic confinement, where superhot plasma is forced into a ring shape by powerful magnets which presses together a stream of hydrogen gas until fusion occurs.
While fusion reactions have been performed and observed on Earth, non-so far have been able to produce more energy than was used to initially trigger the reaction.
As such, most current fusion experiments are simply ‘proof of concept’ demonstrations, in which scientists are trying to prove fusion can be a viable energy source, as opposed to creating an actual power generator.
Despite this seemingly gloomy absence of results, new milestones are continuously being broken.
Earlier this year, in May, China’s Experimental Advanced Superconducting Tokamak (EAST) set a world record, keeping fuel stable for 100 seconds at a temperature of 120,000,000 degrees.
In August, The United States’ National Ignition Facility (NIG) saw a breakthrough, returning 70% of the laser energy provided returned as energy.
Finally, and maybe most excitingly, the world’s largest magnetic fusion machine, Iter, is currently under construction, which scientists believe may result in a net energy gain.
Private enterprise
Another key driver in nuclear fusion’s recent rise to prominence is the swathe of new investment coming in from private investors.
As humanity has made progress in fusion technology, and the need for alternative energy sources has grown, companies and private individuals are battling it out to get to this potential Holy Grail of renewable energy first. This has driven more and more investment from philanthropists, venture capitalists, billionaires and even other energy companies.
With all this new capital, the industry has the capacity to go further than ever.
So, will it work?
Professor Ian Chapman, the head of the United Kingdom Atomic Energy Authority, has said ‘It’s a matter of when, not if’.
It is undeniable that fusion’s prospects as a potential energy source have improved in the last decade, with experts agreeing it is inevitable that we will eventually hit the sought-after goal of a net energy gain.
However, the challenge of scale-up looms.
Even if we do prove fusion power is possible, the time and resources required to scale it up as a accessible power source will be immense. Manufacturing, transporting and assembling highly complex instrumentation presents a huge challenge, and that doesn’t even begin to take into account planning, power infrastructure requirements, raw materials sourcing, legislative approval and bureaucratic management.
Nonetheless, it still stands as a potential answer to some of humanity’s prayers. Any renewable, zero-carbon power source will come as a great help as the world transitions towards a post-fossil fuel era.
Expect to see the words nuclear fusion a lot more in the coming decades.