Today I’m starting a new blog series on fusion.
Nuclear fusion is the energy source that powers the Sun and the stars, and for humanity it could become an almost limitless and clean source of electricity. (The Sun and many other stars generate light and heat by nuclear fusion reactions in which light atomic nuclei such as hydrogen fuse together, releasing energy in the process).
At the same time, it has long been considered one of the most difficult technologies to realize, often joked about as being “30 years away, and always will be.”

Still, the reason I’m strongly drawn to fusion is simple.
If we truly manage to commercialize it, it could transform global geopolitics around energy, industrial structures, and even the future of regional economies and local cities.
I also feel that this “30 years away” era is finally starting to shift into a real countdown.
Around the world, investment in fusion startups is accelerating, and since the mid‑2020s, one company after another has begun raising hundreds of millions of dollars for fusion development.

What exactly is nuclear fusion?

Nuclear fusion is a reaction in which light atoms fuse together into heavier atoms and release energy in the process.
In the core of the Sun, hydrogen nuclei fuse into helium, and that process produces an enormous amount of energy.

For fusion power plants on Earth, the leading approach is to use deuterium and tritium—both “relatives” of hydrogen—as fuel.
When this reaction occurs, it emits high‑energy neutrons, and their heat can be captured and converted into electricity.
Seawater contains abundant deuterium, so in theory “one liter of seawater could yield energy equivalent to hundreds of liters of gasoline.”

The nuclear power plants we use today, based on nuclear fission, take a very different approach: they “split” heavy atoms such as uranium to release energy.
Compared with fusion, fission produces more long‑lived radioactive waste and carries a higher risk of core meltdown accidents.
Fusion is not just another fuel choice; in terms of safety, waste, and resource availability, it could become a fundamentally different option.

Why is fusion entering “serious mode” now?

In the past few years, the landscape around fusion has clearly changed.
In the United States, national laboratories using powerful lasers have repeatedly achieved so‑called ignition or breakeven, where the energy released by fusion exceeds the energy delivered to the fuel.
Meanwhile, large international projects in Europe, Japan, and elsewhere are building huge tokamak‑type devices, aiming for full‑scale operation in the 2030s and beyond.

On the private side, advances in high‑temperature superconducting magnets, power electronics, and simulation technologies have encouraged startups to pursue “smaller and cheaper” fusion reactors.
In Japan as well, major corporations, universities, and the government are beginning to work together to nurture fusion as a next‑generation industry.

What I want to do with this blog

Through this blog, I plan to gradually explore topics such as:

• Fusion basics from the ground up: What is plasma? Why do we need not just ten million degrees, but temperatures on the order of one hundred million degrees?
• Different technical approaches: Tokamaks, laser fusion, and the novel concepts being pursued by startups.
• Business and investment perspectives: Who the key players are and where capital is beginning to concentrate.
• The role of Japan and Kyushu: Materials, components, power systems, regulation, taxation, and legal aspects, connected to my own areas of expertise.

Rather than academic papers aimed at specialists, I want to stand in the space “between business and technology” and follow the reality and potential of fusion from a practitioner’s point of view.

Day 1 declaration

Many people still say fusion is just a dream, and even if it becomes practical, electricity prices might not necessarily fall—there are plenty of sober critiques.
Even so, it is a fact that people, capital, and technologies from all over the world are starting to gather in this field.

In this first post, I’ve shared why I care about fusion and roughly what kind of technology it is.
From tomorrow onward, I’ll start by explaining in more detail the differences between fission and fusion and the basic principles of fusion, using simple diagrams and analogies where helpful.