State-owned Korea Electric Power Corp. will embark on building a power grid along the country’s western coast in an effort to directly transmit electricity from solar and wind power complexes in the southwestern region to the Seoul metropolitan areas to ease the supply and demand imbalance.

According to the reports by Maeil Business Newspaper on Sunday, KEPCO is considering the construction of a backbone network using high-voltage direct current (HVDC) in the West Sea as a measure to cope with the recent power grid crisis.

Although renewable energy supply in Jeolla Provinces is rapidly increasing every year under the nation’s goal of achieving carbon neutrality, the current electricity network far lacks the capacity to transmit power to metropolitan areas from the region. It takes nine 345-kilovolt transmission lines to send electricity generated from renewable energy in Jeolla Provinces to metropolitan areas across land and some of them will be done using HVDC on the nation’s western coast.

The power grid construction will take place offshore, but doing it under the sea will also be considered. Undersea cables are being considered to speed up the project despite the higher cost as offshore construction may face strong opposition from residents.

Power industry insiders note that output control will be needed shortly for terrestrial cables in Korea.

Output control is a measure used to stop power generation in the event of electricity oversupply. It is needed as a large-scale power outage can occur if the output is not controlled.

The International Energy Agency defines four stages of renewable energy supply. Renewable energy accounts for less than 3 percent of total power generation in the first stage, 3 percent to 15 percent in the second, 15 percent to 25 percent in the third and 25 percent to 50 percent in the fourth. From stage three, there is a high possibility or necessity for output control.

Offshore renewable energy in Korea is expected to reach the third stage in 2027. Output control has mostly occurred in Jeju thus far, but the terrestrial grid is likely to face the same situation in light of future policies, including Korea’s 10th basic plan for electricity supply and demand. This is why the increase in solar and wind energy requires power grid expansion.



According to KEPCO, domestic solar and wind energy capacity reached 27,961 megawatts at the end of last year. It was 13,413MW in 2018, 16,058MW in 2019, 20,545MW in 2020 and 24,855MW in 2021. By region, South Jeolla Province has the largest capacity at 5,128MW, followed by North Jeolla Province, North Gyeongsang Province, South Chungcheong Province, Gangwon Province and Gyeonggi Province.

Experts say now is the optimal time to expand the HVDC-based capacity on the west coast.

“The current Korean power grid has a relatively low transmission capacity and uses alternating current that is hard to operate,” said Moon Seung-il, a professor at the Korea Institute of Energy Technology. He referred to HVDC expansion as “digitalizing the power grid using direct current” and said, “Having HVDC infrastructure on the western coast will enable convenient and safe transmission of huge electricity.”

“Renewable energy, such as solar power, tends to be generated into direct current from the beginning,” said Lee Jong-pil, head of the Power Conversion System Research Center at the Korea Electrotechnology Research Institute. “HVDC is a prerequisite for incorporating renewable energy into the current electric power network.”

However, concerns are high that debt-ridden KEPCO may struggle in its West Sea HVDC construction project given the enormous cost. The utilities company posted an operating loss of more than 32 trillion won ($24.7 billion) last year. Potential backlash from residents also poses a challenge to the project.

By Song Gwang-sup, Lee Jin-han, and Choi Jieun

[ⓒ Pulse by Maeil Business Newspaper & mk.co.kr, All rights reserved]