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Han River to heat, cool subway platforms, indoor spaces at future transit center

Published: 07 Apr. 2026, 17:12

A patrol boat cruises in the Han River in southern Seoul on Jan. 21. [YONHAP]

Water from the Han River will both heat and cool subway platforms and indoor spaces at a soon-to-be-built transit center in Gangnam District, southern Seoul, the city government announced on Monday.

The Seoul Metropolitan Government and the state-owned Korea Water Resources Corporation (K-water) agreed to undertake a thermal energy supply project for the Yeongdong-daero transit complex in southern Seoul.

The project will mark the first time that the city applies thermal energy sourced from water to public infrastructure and is expected to be cost effective and environmentally friendly, according to the city government.

The plan works by transferring the heat resulting from the temperature difference between the water of the Han River and the atmosphere.

Typically, the river’s water temperature is about 20 to 26 degrees Celsius (68 to 78 degrees Fahrenheit) in the summer, particularly in July and August, which is lower than the average atmospheric temperature in the mid-30s Celsius. During winter, on the other hand, especially between January and February, the water temperature is about 3 to 5 degrees Celsius, which is relatively higher than subzero air temperatures.

A rendered image shows a view of the Yeongdong-daero transit complex in Gangnam District, southern Seoul. [SEOUL METROPOLITAN GOVERNMENT]

In the summer, the heat exchanger will help channel the heat inside the building to the river, while in the winter, the contraption will use the warm river water to provide indoor heating.

Currently, a metropolitan water supply pipeline capable of utilizing water-based thermal energy is installed at Bongeunsa-ro, a road about 100 meters (328 feet) from the upcoming transit center. Meanwhile, the Coex mall in Gangnam and the Lotte World Tower in Songpa District, also in southern Seoul, are using water-sourced thermal energy via the pipeline.

A rendered image shows a bird's-eye view of the Yeongdong-daero transit complex and its surrounding neighborhood in Gangnam District, southern Seoul. [SEOUL METROPOLITAN GOVERNMENT]

Under the recent agreement, the city plans to extend that pipeline to the transit center.

“Using the river water, which experiences less temperature fluctuation than the atmosphere, offers an advantage in terms of operating costs,” a city official said. “[The system] is also economically beneficial in terms of construction costs, as a primary pipeline for wide-area waterworks in the greater Seoul area already passes near the project site.”

The primary pipeline for the greater Seoul area, including Gimpo and Incheon, takes water from Hanam, a city in Gyeonggi, and supplies that to districts including Gangnam, Seocho, Songpa and Yeongdeungpo.

The city estimates that approximately 620 million won ($412,000) will be saved annually once the thermal energy system is introduced at the transit center. Additionally, a total of 1,498 tons of greenhouse gas emissions is expected to be reduced.

A rendered image shows the outdoor spaces of the Yeongdong-daero transit complex in Gangnam District, southern Seoul. [SEOUL METROPOLITAN GOVERNMENT]

The use of water-based thermal energy will help create a more harmonious landscape in the ground-level outdoor plaza, as cooling towers, which are typically required for conventional heating and cooling systems, will not be necessary.

Once the cooling towers are removed at ground level, the urban heat island effect and noise are expected to be alleviated. The urban heat island effect is a phenomenon in which urban areas have higher temperatures than rural ones because heat is trapped between densely populated high-rise concrete buildings.

Construction of the transit center will be completed in 2029. Multiple lines of high-speed rail services — including the A and C lines of the Great Train Express, lines Nos. 2 and 9 of Seoul’s subway and the Wirye-Sinsa light rail line — will stop at the transit center. The facility will also host venues for cultural activities, such as performances and exhibitions.

“Water-sourced thermal energy supplied from the Han River is the first step in transforming the energy paradigm of urban infrastructure,” said Lim Chun-geun, the head of the Seoul Metropolitan Infrastructure Headquarters.

“We will proceed with the plan without disruption until operations begin in 2030.”

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY MOON HEE-CHUL [[email protected]]