Yilan drilling confirms high-potential geothermal site: Institution

Taipei, Dec. 10 (CNA) The first deep geothermal test well in Yuanshan Township, Yilan County, has confirmed a high-potential site after temperatures of nearly 150 degrees Celsius were recorded at a depth of nearly 4,000 meters, Academia Sinica said Wednesday.

Academia Sinica, Taiwan's leading research institution, and the state-owned energy company, CPC Corp., Taiwan, began drilling the well in October 2024 and completed drilling and an integrated geological and thermal analysis in August 2025.

Initial findings showed an upwelling heat source beneath the northern Yilan Plain, indicating strong development potential, Academia Sinica said in a statement.

Taiwan is full of hot springs and fumaroles, considered to be signs of potential sources of geothermal energy, and experts believe Taiwan has a deep geothermal power generation potential of between 25 GW and 32 GW, enough to provide a sizable chunk of the country's power.

Yet Taiwan has not seen any breakthroughs in developing geothermal energy for decades. Its first geothermal power plant was founded in 1981 but operations at that plant were suspended in 1993 because of growing inefficiencies.

A new facility was opened in Yilan County's Datong Township in 2023, but that still only provided 0.003 percent of all electricity generated in Taiwan in the first 10 months of 2025, according to Energy Administration statistics.

Even the latest drilling site initially caused some anxiety.

Lee Jian-cheng (李建成), who leads Taiwan's national geothermal research program and is a research fellow at Academia Sinica's Institute of Earth Sciences, recalled that the team became concerned when temperatures remained below 100 degrees Celsius at around 3,000 meters.

Temperatures then rose rapidly beyond 3,500 meters -- by an estimated 90 degrees per kilometer -- before reaching about 150 degrees at the well's bottom.

The data suggested that the site is close to a high-temperature center, where temperatures suitable for geothermal energy development may be reached at depths as shallow as 3,000 meters, Lee said.

According to the Ministry of Economic Affairs, for geothermal power generation to be economically viable, the temperature of hot water or steam at the wellhead generally needs to reach at least 120 degrees, with higher temperatures and greater flow rates offering better efficiency.

Drilling data at the test site also indicated that the lower geological formations are suitable for a newer, low-seismic-risk hydraulic stimulation method that can improve hot-water flow paths and support geothermal extraction, Academia Sinica said.

Chen Yue-gau (陳于高), executive secretary of Academia Sinica's Center for Sustainability Science, said international experience shows three to five test wells are usually needed to develop a geothermal field.

The strong results from the Yuanshan well support further drilling to map the geothermal system's three-dimensional structure and guide future engineering design, he said.