South Korea's projected peak electricity demand in 2040 has surged by 26.8 gigawatts in just four months, driven primarily by massive new semiconductor facilities and AI data centers that will require the equivalent of approximately 19 large nuclear reactors to power. The country's Ministry of Climate, Energy and Environment unveiled the revised forecast during a National Assembly forum, signaling an urgent pivot toward nuclear energy as the nation races to maintain its competitive edge in advanced manufacturing and artificial intelligence.

Why Did South Korea's Energy Forecast Jump So Dramatically?

In April, South Korea projected peak electricity demand of 131.8 to 138.2 gigawatts by 2040. Four months later, that estimate climbed to 158.4 to 165 gigawatts, a roughly 20 percent increase. The primary culprits are three megaprojects: the Honam semiconductor cluster in the southwestern region, new semiconductor fabrication plants in Yongin, Pyeongtaek, and Cheongju, and a wave of AI data center investments.

The numbers are staggering. Additional electricity demand from semiconductors and advanced industries beyond their existing growth trajectory jumped from 3.7 to 4 gigawatts in April to 24.3 to 24.6 gigawatts in the revised forecast. AI data center demand nearly tripled, rising from 4 gigawatts to 11.9 gigawatts. By 2040, the government estimates potential semiconductor electricity demand alone could reach around 40 gigawatts of contracted capacity, with 36.8 gigawatts incorporated into the latest forecast.

To put this in perspective, South Korea's current peak electricity demand stands at approximately 100 gigawatts. The new forecast means peak demand will exceed 1.5 times current levels within 14 years, driven almost entirely by industrial expansion in chips and AI infrastructure.

What Makes Nuclear Power the Only Viable Option?

Semiconductor plants and AI data centers present a unique power challenge. Unlike typical industrial facilities, they concentrate massive electricity loads at single sites and require consistent, high-level power around the clock. This steady demand pattern rules out many renewable energy sources that generate power intermittently.

"Advanced industries generate relatively even loads throughout the day. Among carbon-free energy sources, nuclear power is effectively the only option capable of responding well to these electricity load patterns and meeting demand," stated Park Woo-young, head of energy transition policy research at the Korea Energy Economics Institute.

Park Woo-young, Head of Energy Transition Policy Research, Korea Energy Economics Institute

The timeline for construction adds urgency to the decision. Offshore wind farms, nuclear power plants, and transmission infrastructure all require approximately 10 years to build. Delaying investment now could leave South Korea scrambling to meet demand in the 2030s, potentially losing competitiveness to other nations.

How Is South Korea Planning to Meet This Energy Demand?

The government's 12th Basic Plan for Long-Term Electricity Supply and Demand, expected to be finalized by the end of the year, will determine whether South Korea builds additional nuclear reactors beyond the two large reactors and one small modular reactor already included in the 11th plan. The previous plan had already selected sites for these three reactors, but the new demand forecast suggests significantly more capacity will be needed.

• Nuclear Reactor Expansion: The government must decide whether to construct additional large reactors beyond the two already planned, potentially including more small modular reactors that can be deployed faster and with lower upfront costs.
• Liquefied Natural Gas Plants: LNG power generation is being considered as a complementary option, though it produces carbon emissions unlike nuclear power.
• Transmission Infrastructure: New power lines and grid upgrades are essential to distribute electricity from generation sites to semiconductor clusters and data centers, a process that itself takes years to complete.
• Renewable Energy Integration: While renewables cannot meet the steady baseload demand alone, they may play a supporting role in the overall energy mix.

The government applied relatively conservative criteria to AI data center projections. Companies submitted investment plans totaling 20.8 gigawatts of contracted capacity by 2040, but the government incorporated only 10.8 gigawatts from the first phase, for which specific details like locations and scale have been confirmed. The remaining 10 gigawatts will be monitored before inclusion in future plans, reflecting the higher uncertainty surrounding AI data center investments compared to semiconductor manufacturing.

What Are the Risks of Moving Too Slowly or Too Fast?

South Korea faces a delicate balancing act. Move too slowly on nuclear investment, and the country risks power shortages that could cripple its semiconductor and AI industries, handing competitive advantage to rivals like Taiwan and the United States. Move too fast, and the nation could overbuild capacity, wasting billions on infrastructure that sits idle.

"It would be a major strategic mistake if a lack of energy supply prevents us from pursuing advanced manufacturing or AI industries that other countries are developing," said Kim Hee-jip, a professor at Seoul National University's Graduate School of International Studies.

Kim Hee-jip, Professor, Seoul National University's Graduate School of International Studies

Some experts warn against over-relying on uncertain industrial demand projections. Han Ga-hee, head of the energy policy team at Solutions for Our Climate, cautioned that incorporating unverified figures could result in overinvestment in generating capacity. The distinction matters because nuclear plants operate for decades, and building excess capacity locks in long-term costs.

How Does This Compare to Global Nuclear Investment Trends?

South Korea's pivot toward nuclear energy mirrors a broader global trend. Advanced reactor developers like NuScale Power and Oklo are racing to commercialize small modular reactors (SMRs) specifically designed to power data centers and industrial facilities. However, the nuclear sector has faced recent headwinds. On August 20, NuScale Power stock fell 5 percent, Oklo dropped 5 percent, and Centrus Energy sank 6 percent, reflecting investor concerns about interest rates and the lengthy timelines before these companies generate meaningful revenue.

Meanwhile, companies like Kairos Power are taking a different approach to de-risking nuclear construction. Kairos broke ground on its Hermes 2 demonstration plant in April 2026 at Oak Ridge, Tennessee, using an iterative development strategy that tests construction and manufacturing techniques at each phase before scaling up. The company has signed a power purchase agreement with Google and the Tennessee Valley Authority to supply 500 megawatts of power by 2035, demonstrating how advanced reactors are being positioned to serve AI data center demand.

South Korea's decision to pursue additional nuclear capacity will likely influence global supply chains for nuclear fuel and components. The country's government must balance the urgency of industrial demand against the reality that nuclear projects require careful planning, regulatory approval, and years of construction before delivering power to the grid.