Fusion is great. In music. In food. One of my favourite New York restaurants was a place that offered a Cuban-Chinese fusion menu. This piece however is not about grub or jazz, but about one of the holy grails of physics, and that is nuclear fusion… as an energy source.
The Hydrogen dog And the Cobalt cat,
side by side in the armory sat,
Nobody thought about fusion or fission.
Everyone spoke of their peacetime mission,
till somebody came and opened the door.
There they were, in a neutron fog.
The Codrogen Cat And the Hybalt dog;
they mushroomed up with a terrible roar,
and nobody never was there no more.
– Frederick Winsor
First up is just plain old regular fusion. Well… I say regular. Nuclear fusion is the process that takes place in stars like our sun. It’s also the process that takes place in hydrogen bombs, although I am going to stay clear of that topic. So, what is fusion, and why is it interesting? First off… nuclear fusion is the process where two light atomic nuclei combine to form a single heavier nucleus. Massive amounts of energy are the result. Fusion happens in stars because nuclei collide with each other at extremely high temperatures. This temperature, in the range of 10 million degrees C provides them with the energy to overcome their natural mutual electrical repulsion allowing the nuclei to come within a very close range of one another. The attractive nuclear force between them now outweighs the electrical repulsion and allows them to fuse. Along with this, the nuclei must be confined within a very small space to increase the chances of collision. In stars this confinement is caused by the extreme pressure produced by their tremendous gravity.
Could this type of reaction be artificially induced on a small scale is the question that is the crux of this topic. It’s a question that has been around since the 1930’s when the theory of fusion was first understood. It’s a question that is worth answering too, because it holds the promise of a safe, clean, and virtually limitless affordable energy supply.
The big draws of fusion are twofold. The first being the ready supply of fusion-able materials. The second being the relative safety of the process. It’s safe because of the radioactive decay of the materials involved, and it’s safe because of the fact the reaction cannot get out of control, or runaway like what we see in the meltdowns in nuclear fission reactors.
Fusion reactions take place in a specific state of matter called plasma — a hot, charged gas made of positive ions and free-moving electrons with unique properties distinct from solids, liquids or gases.
You are probably wondering… what’s the big deal, why are those scientist fellows studying fusion energy?
It’s pretty simple. Fusion could generate up to four times more energy per kilogram of fuel than the fission process currently used in nuclear power plants, and a whopping four million times more energy than burning the same amount of oil or coal.
Most of the fusion reactor concepts under development use a mixture of deuterium and tritium (hydrogen atoms that contain extra neutrons)
Deuterium is abundant in seawater, and tritium can potentially be produced from the reaction of fusion generated neutrons with naturally abundant lithium.* A few grams of these reactants can produce the energy requirements of a person in a developed country for over sixty years. These fuel supplies could likely last for millions of years.
*this is still somewhat theoretical in a commercial scale power generation scenario
Additionally and importantly, from an environmental and climate change perspective, nuclear fusion does not emit carbon dioxide or other greenhouse gases into the atmosphere.
From a technological standpoint there are a number of competing approaches to nuclear fusion. These are all based on how to contain the fusion reaction in the plasma. The most popular ones being: Magnetic Confinement, Inertial Confinement, Magnetic or Electric Pinches, and Inertial Electrostatic Confinement. The front runners are in the Magnetic Confinement category, most specifically with the device known as a Tokamak.
A Tokamak is a method that drives hot plasma around in a magnetically confined torus with an internal current. I found a list of 103 experimental Tokamaks were either planned, decommissioned or operating worldwide spanning the years from 1957 to 2050. Currently there are about 32 operational Tokamaks worldwide. It needs to be noted that thus far all operational Tokamaks are of experimental nature and not close to being functional on a commercial power production scale. In fact since the first experiments in the 1940’s there have been no examples of net power generation, although there have been some net positive reactions.
Net power = Efficiency × (Fusion − Radiation loss − Conduction loss)
These mediocre results certainly haven’t quenched the search, and there are many experiments ongoing and actual reactors scheduled to come online in the coming years. Mankind has an insatiable need for energy, and nuclear fusion could be poised to supply that appetite, and fuel civilization for millennia to come.
Another reason to hold out hope for the promise of fusion, is to power all of the cool stuff in our favourite science fiction. From starship drives, to Tony Stark’s Iron Man suit…
Even more out there, and still firmly in the realm of science fiction is the concept of Cold Fusion. Most real science guys would balk at the inclusion of the topic in any context related to nuclear fusion. But heck… I’m not a real science guy, and we’re just supposing to be having fun here at PGH right?
Cold Fusion is a highly hypothetical nuclear reaction that would take place at, or close to ‘room temperature’. The idea has been around as long as we started to understand the nuclear world in the 1920’s. In the late 1980’s there was a flurry of interest over an experiment that claimed to have generated net positive energy from a cold reaction. This experiments results were never able to be replicated, although many tried, and the whole thing was quickly debunked.
Mainstream science has pretty much abandoned Cold Fusion as quackery. In fact even the term Cold Fusion has become synonymous with snake oil. The U.S. Patent office actually refuses to look at patents that mention the term. As a result, funding for Cold Fusion experiments is practically impossible, and what little research that is being done never gets published in peer reviewed papers. That being said there is still a small group of researchers throughout the world that are doggedly working on the concept, and there are some carefully worded patents out there as well. If you are curious and want to find out more, look for terms like: LENR, CMNS, and LANR
Additionally there is a world conference on the subject. There have been 25 conferences since 1990, the most recent being in 2023. If you are interested in attending, the next one is in Japan from the 26th to the 30th of May, 2025. Have fun…