Starting this year, the government will expand a project to use groundwater (discharged groundwater) that flows out during development of underground spaces such as subways and tunnels for heating and cooling.
Discharged groundwater stays around 15 degrees Celsius year-round. In summer, cooler groundwater than the outside air passes through a heat exchanger to cool indoor air, and in winter, a heat pump amplifies the relatively warm groundwater's thermal energy to heat indoors.
Although it has the advantage of being an eco-friendly heating and cooling facility, the initial installation expense runs into hundreds of millions of won, making it more expensive than existing cooling systems.
According to a compilation of reporting by ChosunBiz on the 22nd, the Ministry of Climate, Energy and Environment increased the budget for the "pilot project to install facilities using discharged groundwater," which began at Munhyeon Station in Busan in 2020, from 460 million won last year to 5.51 billion won this year, more than a tenfold rise. The project provides partial support for design and installation costs to local governments and private operators that are pushing to install facilities using discharged groundwater.
Last year, construction of related facilities began at Sujeong Station and Yeonsan Station in Busan, and this year design work is underway at Buan Station in Busan and the Gwangmyeong Hakon public housing district in Gyeonggi Province. A Ministry of Climate, Energy and Environment official said, "We are currently in budget talks with the Ministry of Planning and Budget to expand the scale of next year's project beyond this year."
The government moved to expand the project because it produced savings in heating and cooling fees at Munhyeon Station in Busan. According to the ministry, using 360 tons per day of discharged groundwater for cooling at Munhyeon Station cut electricity bills to about half compared with stations of a similar size.
Since then, multiple subway stations have applied to join the project. The government is also pushing to introduce heating and cooling facilities using discharged groundwater at exhibition halls run by local governments and at general buildings.
Heating and cooling that uses groundwater is spreading overseas as well. In the Netherlands, heat and cold are stored in aquifers—groundwater layers 150 to 500 meters below the surface where temperatures remain stable—and then extracted in summer and winter for heating and cooling. There are about 2,500 such aquifer thermal energy storage (ATES) systems in operation. Sweden, Germany, Belgium and Denmark are also expanding the same system to large buildings, hospitals and industrial facilities.
Some caution that installation expense is higher than existing cooling systems, reducing efficiency and making nationwide expansion difficult. In response, a ministry official said, "We assess that energy efficiency is high enough to recoup the initial investment in a short period."