Hydrothermal energy potential near the three major metropolitan cities in Korea

The potential for hydrothermal energy of the river, raw water, and reservoir water, which were located near the three major metropolitan cities in Korea, was predicted. The natural energy potential was defined by the flow rate of each water source, utilizing the temperature difference of 5 °C. Exceptionally, the amount of flow for the reservoir water was assumed to be 1 % of the dam’s storage amount for month. The technical potential for the hydrothermal energy for each water source was calculated by simulation of the whole water-source heat pump system through TRNSYS. The hydrothermal energy potential of the Han River in Seoul, Nakdong River in Busan, and Gapcheon in Daejeon are (227678, 247360, and 14600) TJ/year, respectively. In estimating the technical potential for the Han river, the average COP for the river-water heat pump system is 4.40 for cooling and 3.11 for heating, with a monthly maximum COP of 5.79, and a minimum COP of 3.01. One of the raw water pipelines in Seoul is connected in the form of the Gangbuk water purification plant-Gangbuk water intake plant. The technical hydrothermal energy potential is 5682 TJ/year. For Paldang Dam, the average COP for the reservoir water heat pump system is 3.28 for heating, and 4.26 for cooling, while the technical potential is 595 TJ/year.