S. Korea aims to lead fusion energy race with homegrown reactor by 2035

"The dream energy source is becoming reality."

Soaring power demand driven by climate change and the spread of AI is pushing the search for next-generation energy sources, and fusion energy — often called the "artificial sun" — is rapidly emerging as a leading candidate. Major powers including the United States, China and the United Kingdom, along with private companies armed with vast capital, have joined the race, intensifying competition for leadership in fusion commercialization.

South Korea is making its move. The government has included fusion energy in its "Seven SEED Projects," a national initiative aimed at a science-and-technology-driven transformation of the country's future, with a push toward early commercialization. The goal is to complete a "Korean innovative fusion reactor" by 2035 and demonstrate actual power generation by 2039.

Fusion replicates on Earth the process by which the sun produces light and heat — fusing light atomic nuclei such as deuterium and tritium to release enormous amounts of energy for electricity generation. One gram of fusion fuel can yield energy equivalent to about 8 tons of oil.

The deuterium extractable from roughly half a bathtub of seawater, combined with the amount of lithium found in a laptop battery, can produce enough electricity to power one person for decades.

The abundance of deuterium and lithium in seawater makes fuel supply an advantage. Fusion also emits no carbon during power generation.

Unlike nuclear fission, fusion does not rely on a chain reaction — if the fuel supply is cut or plasma containment conditions break down, the reaction stops quickly. Most radioactive waste from a fusion reactor is also targeted to be managed as low- to intermediate-level waste.

"The depletion of oil resources is already an inevitable trajectory, and renewable energy sources such as solar and wind alone have limits in meeting total energy demand," said Oh Young-kook, president of the Korea Institute of Fusion Energy. "Fusion is the new high-efficiency energy source that can replace the enormous energy demand currently met by fossil fuels."

The global race is accelerating. What was once a field dominated by governments and international research consortia has seen a surge of private-sector participation, sharply speeding up the push toward commercialization.

According to the Fusion Industry Association, private fusion companies worldwide attracted $4.48 billion in new investment over the past year across 56 firms — a sign that fusion is rapidly shifting from long-horizon basic research to an industry targeting actual power generation.

The United States unveiled its "Bold Decadal Vision" in 2022 to accelerate fusion energy development. Private companies including Commonwealth Fusion Systems, Helion Energy and Pacific Fusion have secured massive funding and entered the race for early commercialization.

China is pressing ahead with construction of its next-generation fusion experimental device, BEST, while the United Kingdom is pursuing power generation demonstration through its STEP (Spherical Tokamak for Energy Production) project.

Private companies in particular are moving away from the traditional model of spending years building a single large experimental reactor. Instead, they are opting for a strategy of rapidly building smaller fusion devices and running repeated experiments. The competition has effectively become a race to see who can generate electricity first.

At the heart of South Korea's fusion program is KSTAR, the Korea Superconducting Tokamak Advanced Research device. South Korea developed KSTAR — an advanced tokamak-type device built entirely on domestic technology — and has operated it since 2007.

A tokamak confines ultra-high-temperature plasma exceeding 100 million degrees Celsius inside a vacuum vessel using powerful magnetic fields. Because plasma instantly loses heat upon contact with the vessel wall, superconducting magnets must control it with precision.

KSTAR has successfully sustained a plasma core ion temperature of 100 million degrees for 48 seconds — more than six times the roughly 15 million degrees at the sun's core.

The device has also achieved world-class results in long-duration high-performance plasma operation, maintaining the standard high-performance H-mode for 102 seconds in a tungsten environment — the material slated for use as the inner wall of future fusion demonstration reactors.

The next target is 300 seconds at 100 million degrees.

"Our goal is to secure the technology to sustain and control plasma at temperatures above 100 million degrees for more than 300 seconds within one to two years at the latest," Oh said. "Surpassing 300 seconds is an important step in experimentally verifying the possibility of continuously maintaining ultra-high-temperature plasma without time constraints."

To that end, KSTAR's plasma-facing inner wall is being replaced with tungsten. Since future fusion reactors are expected to use tungsten, the upgrade will allow researchers to develop long-duration operating technology in conditions as close as possible to an actual fusion reactor.

South Korea also plays a key role in the International Thermonuclear Experimental Reactor, or ITER, currently under construction in Cadarache in southern France.

ITER is the world's largest superconducting fusion experimental reactor, with seven member parties — South Korea, the United States, Russia, the EU, Japan, China and India. Its goal is to verify the scientific and technological feasibility of fusion energy at scale. Total construction costs stand at approximately 21.74 billion euros ($25.4 billion), with research operations targeted to begin in 2034.

South Korea contributes 9.09 percent of the total project cost and is responsible for developing, manufacturing and supplying nine key components. Four items — superconducting conductors, the vacuum vessel body, assembly equipment and thermal shields — have already been delivered, while power supply systems, vacuum vessel ports, blanket shielding blocks, diagnostic devices and a tritium storage and supply system are still being manufactured and procured.

Participation in ITER goes beyond a share of an international project — it gives South Korea's domestic fusion industry and research institutions a chance to build technical capabilities directly. Domestic organizations and companies are developing advanced technologies needed for commercial fusion power plants, including superconductivity, ultra-high vacuum, cryogenics, precision manufacturing and power supply systems, accumulating hands-on experience in the process.

Building on that foundation, the government has laid out a blueprint to complete a Korean innovative fusion reactor by 2035 and demonstrate power generation by 2039. The strategy applies high-temperature superconducting technology and other advances to a device smaller than ITER, boosting performance while reducing construction costs.

Full-scale design of the innovative fusion reactor is set to begin this year, with AI to be actively incorporated. Through an "acceleration strategy" that aims to compress research and development cycles that previously took about a decade down to one or two years, South Korea intends to get ahead of major competitors in the commercialization race.

Significant hurdles remain, however. Outstanding technical challenges include stably sustaining plasma above 100 million degrees for extended periods, developing blanket systems to convert fusion heat into electricity, tritium breeding and recovery, materials capable of withstanding extreme conditions, remote maintenance and integrated reactor control.

"With Naju in South Jeolla Province selected as the site for key technology development infrastructure, we plan to accelerate efforts to secure space for research on core technologies for compact fusion reactors and blanket systems needed for power generation," Oh said. "It is crucial to connect the technologies acquired through KSTAR and ITER to the innovative fusion reactor and bring forward the commercialization of fusion energy."