[Public Voices] The Multiplayer of the Power System: Pumped-Storage Power Plants

Kwon Chang-seop, Head of Hydropower Division, Korea Hydro & Nuclear Power

Yangsu-gyeomjang (兩手兼將). This term is used in games like Janggi (Korean chess) or Baduk (Go) when a single move achieves two effects. It is similar to expressions like "killing two birds with one stone." When applied to people, the term "multiplayer" is also used. Fans would be thrilled by a baseball player who is both a fastball pitcher and a home run hitter, or a soccer player who is a top forward scorer while also excelling as a defender when needed.

There is also a multiplayer in the power system, and that is the pumped-storage power plant. Unlike other power plants that only generate electricity, pumped-storage plants serve two roles. When there is excess electricity, they pump water up to the upper reservoir, and when electricity is in short supply, they release this water down to the lower reservoir to generate power. It acts like a kind of battery. In South Korea, during the 1970s, as nuclear and large thermal power plants were built, pumped-storage plants were promoted to increase the utilization rate of large-scale power plants and ensure the stability of the power system. This was because pumped-storage was the only economical way to store large amounts of energy. Subsequently, starting with Cheongpyeong pumped-storage in 1980, Samrangjin and Muju pumped-storage plants were constructed in sequence.

Since the 2000s, issues with stable operation of the power system have emerged due to the expansion of renewable energy sources. Electricity supply and demand must match in real time, but solar and wind power cannot adjust their output according to real-time demand fluctuations. Therefore, additional reserve capacity resources were needed, leading to the construction of additional pumped-storage plants in Sancheong, Yangyang, Cheongsong, and Yecheon. Currently, South Korea operates seven pumped-storage plants with a total capacity of 4.7 GW.

As expected, pumped-storage plants are playing a vital multiplayer role in the power system. They can produce electricity within about three minutes, so in emergencies such as sudden increases in power demand or unexpected shutdowns of large power plants, they immediately supply large amounts of electricity. Additionally, they adjust output in real time according to the power system conditions, playing a key role in maintaining power quality. They can start and generate power independently without external power assistance, so in the event of a nationwide blackout in South Korea, they can supply startup power to other generators and serve as the first power plants to restore the power system.

In particular, recently, daytime pumped-storage operations have surged due to the rapid increase in renewable energy such as solar and wind. Excess renewable energy generated during the day is used for pumping, then power is generated at sunset, followed by pumping using excess wind and large power plant energy at night, and generation in the morning. This greatly contributes to improving the stability and efficiency of power system operation.

Meanwhile, pumped-storage plants also play a role in coexisting with local communities and leading regional development. The Muju pumped-storage plant in Muju-gun, Jeollabuk-do, has a Meru wine cave utilizing an old tunnel, the Yangyang pumped-storage plant in Yangyang-gun, Gangwon-do, has an Energy Farm exhibition hall, and the Cheongpyeong pumped-storage plant in Gapyeong-gun, Gyeonggi-do, offers an upper reservoir trekking course, all of which are popular tourist attractions. Additionally, by securing surplus water in the upper reservoir, they supply agricultural water by releasing it into rivers during droughts and provide firefighting water when forest fires occur in nearby mountains.

This winter, power demand is soaring to record highs due to severe cold. In response, pumped-storage plants nationwide are on high alert and tightening their emergency response posture. Korea Hydro & Nuclear Power, the sole operator of pumped-storage plants in South Korea, is conducting 24-hour equipment inspections and maintenance to fulfill its role as the power system’s Yangsu-gyeomjang, the multiplayer that the public expects.

Kwon Changseop, Head of Hydropower Division, Korea Hydro & Nuclear Power

This content was produced with the assistance of AI translation services.