Building a Sun on Earth through nuclear fusion: an interview with Kim Chang-hwan

Solutions to the climate crisis are most often discovered through scientific research, which serves as the frontier of uncovering new knowledge and technologies that shape our collective future of sustainability. Nuclear fusion is one innovative strategy that joins atoms together and produces water as a byproduct rather than CO2, making it a clean energy source with virtually unlimited fuel derived from seawater. In this interview, researcher Kim Chang-hwan at the Korea Institute of Fusion Energy discussed the Institute's current progress of research and challenges encountered in the long journey of commercializing fusion energy.

First, could you tell us about the field you’re currently researching?

Sure. I currently work at the Korea Institute of Fusion Energy. At the Institute, we’re currently conducting research on a device called KSTAR, which is often referred to as “the Sun on Earth.” Unlike solar energy, which relies on nuclear fission, the Sun is sustained by nuclear fusion energy, and that is what we are researching. The idea behind this research is that since the Sun is the source of all energy, we aim to replicate it here on Earth.

This field is currently gaining a lot of attention as a promising area for future alternative energy, with the potential to generate the largest amount of energy. Until now, we’ve used electricity generated from fossil fuels, and then there’s nuclear energy. Nuclear energy refers to the energy released when an atom is split, or fission, which we convert into electricity. In contrast, nuclear fusion involves fusing atoms together, which produces just as much energy. We are currently conducting research to harness that energy and generate electricity.

How do you see the research you are currently conducting connecting to trends such as improving energy efficiency, reducing electricity consumption, or achieving carbon neutrality?

That’s a very good question. First of all, fusion energy is often described as a clean energy source. This is because it generates energy while minimizing carbon emissions. When we talk about fossil fuels, we’re referring to things like oil and coal. But as you know, when we use fossil fuels, we have to burn them to generate thermal energy. To generate energy from fossil fuels, we use water, and in that process, a significant amount of carbon monoxide—or carbon, as we call it—is produced. That’s why there’s currently a movement to reduce it. However, nuclear fusion energy produces almost no carbon dioxide.

The fuel used for nuclear fusion energy is tritium, which is extracted from seawater. So, when a nuclear fusion reaction occurs using tritium as fuel, the byproduct isn’t CO2—it’s H2O, or water. That’s why it’s an energy source that minimizes carbon dioxide emissions and actually produces oxygen, making it a very sustainable option for us to use.

What is the biggest challenge to increasing the use of fusion energy in Korea?

Currently, the only fusion device Korea has is the KSTAR, which I mentioned earlier. We have that one device, but it is not designed to generate energy. It is an experimental device created to answer the question of whether we can replicate the fusion reactions occurring on the Sun right here on Earth.

So, it hasn’t been commercialized yet. No country in the world has managed to commercialize fusion energy yet, but as a high-pressure research device, Korea’s KSTAR is the most advanced type of fusion device among those in the world. As a result, the data being collected from experiments at Korea’s KSTAR serves as a kind of database for other countries. So, in the field of fusion energy, we are slightly ahead of other countries. However, I don’t know exactly how many years it will take.

I’m also currently developing a fusion device in Korea that is much larger than the existing KSTAR, one that can convert energy into electricity and extract usable energy. You could say it’s in the design phase—or at least at this stage. Within the next few years, this facility will actually be built somewhere. The current K-STAR device is already quite large—about the size of a five-story building—but we expect to build a fusion device that’s three to four times larger, capable of generating electrical energy.

Do you think there are any policy changes or support measures that are most needed before nuclear fusion power becomes commercialized like this?

In terms of energy source development, a lot more research is actually needed before we can generate electricity through nuclear fusion and actually use it. Realistically, my personal view is that we need to develop alternative energy sources to bridge that gap. We need to establish a policy foundation to promote the use of more eco-friendly energy sources, ideally moving away from coal and oil, and to achieve that, I personally hope that among the current alternative energy options, natural gas and hydrogen energy become widely available. To achieve this, the necessary infrastructure must first be in place. In the case of hydrogen energy, for example, separate facilities—known as hydrogen stations—are required to store hydrogen. While the number of such facilities is currently being expanded in our country, I understand that they are still somewhat insufficient. Addressing these infrastructure needs is a priority. 

Another point is that we cannot simply stop using existing energy sources like coal and oil overnight. Therefore, I believe we need a phased plan to gradually reduce their use and replace them with other energy sources, along with policy frameworks to ensure this can be implemented consistently.

As carbon neutrality and other eco-friendly goals become increasingly important, do you have any thoughts on how the nuclear fusion research you’re conducting can help, or how it might develop further to bring us one step closer to carbon neutrality?

First of all, this is a matter of national importance, and at the research institute level, it is our responsibility to prepare so that we can produce good experimental results and commercialize them as soon as possible. Fundamentally, I think the general public needs to give some thought to carbon reduction measures that each individual can practice. 

On a personal level, I have done some social services at my church for several years, where I encouraged and educated people on individual carbon reduction activities. While doing that, when promoting these ideas to others, I often talked about ways to reduce the consumption of energy sources we’re all familiar with—whether it’s electricity, water, or fossil fuels. Although the energy saved by an individual practicing these small, everyday actions may seem negligible, if everyone comes together to reduce consumption, the effect could be far greater than we can imagine. Personally, this is how I see it, and I believe that many people should first focus on thinking about ways to reduce fossil fuel use and carbon emissions—and then actually putting those ideas into practice, no matter how small they may seem.

As a scientist and engineer working in energy development, as I mentioned earlier, I believe my mission is to quickly produce positive research results so that we can reduce our reliance on the energy sources we’ve been using—fossil fuels and nuclear power—and prepare to replace them with fusion energy as soon as possible.