Steam rising from Umi Jigoku (Sea Hell), one of Beppu Onsen's most famous sights, reflects the region's rich geothermal energy. (©JAPAN Forward)
Steam rises from hot springs across Japan, a reminder of the immense heat stored beneath the ground. These are powered by the same natural force now drawing renewed attention as a sustainable energy source: geothermal energy.
Debate over renewable energy has reached a turning point. Surging electricity demand from AI data centers, Sustainable Development Goals momentum, rising energy costs, and economic security concerns are driving the shift.
Yet long before these issues emerged, Japan's onsen culture has developed alongside this powerful resource from deep within the earth.
To find out more, JAPAN Forward visited Beppu Onsen in Oita Prefecture, one of Japan's leading hot spring regions. Beppu has the largest number of hot spring sources in the country and the highest overall volume of hot spring water.
Why Geothermal Energy?
Unlike solar or wind, whose output fluctuates with weather, geothermal offers the strength of a baseload power source, capable of a stable supply all year round.
Japan is one of the world's leading hot spring nations and ranks third globally in geothermal resource potential. The technical capabilities that support geothermal development are also among the best in the world.
In Beppu, geothermal power is not treated as a resource to be extracted in isolation, but as a local asset woven into daily life.
Beppu Onsen: Living in Harmony with Geothermal Energy
The city of Beppu has developed alongside its hot springs, and there is no better person to explain its history than Yoshihiro Hirano, chairman of the Beppu Onsen Hospitality Association. Beyond onsen culture, he has deep knowledge of many aspects of Beppu, including the communities and businesses closely connected to geothermal energy.
Kumahachi Aburaya, known as the founder of Beppu tourism, laid the foundation for the region's strong ties to geothermal energy, guided by a spirit of coexistence with nature and care for others.
Hirano says these values are key to connecting hot spring culture with geothermal development. To see this spirit in action, we headed to a hot spring resort and a farm that makes use of geothermal energy.
Powering Up a Whole Building
One of the best places to experience Beppu's famous onsen is its landmark Beppu SUGINOI HOTEL. There, guests soak in its signature open-air bath, Tanayu, which features five terraced levels, each with a different temperature and sweeping panoramic views of the city.
This large-scale hot spring resort welcomes approximately 2,000 guests a day and is a cornerstone of Beppu's tourism industry.
Yet tourism relies heavily on energy, particularly for transportation and accommodation. To reduce its environmental impact, SUGINOI HOTEL has introduced a range of sustainability initiatives, with the Suginoi Geothermal Power Plant at their core.
Located on the hotel grounds, the plant generates electricity using steam from the hot spring, with an output of 1,100 kilowatts. This power almost entirely supplies SUGINOI Hall, a multipurpose building that includes a 500-seat banquet hall for events such as wedding receptions, with surplus electricity distributed to other facilities across SUGINOI HOTEL.
Built to Withstand Disaster
The plant also plays a critical role in disaster preparedness. In emergencies, SUGINOI Hall can serve as a temporary evacuation shelter for guests. Thanks to the geothermal plant, electricity can continue to operate even during regional blackouts.
This resilience was demonstrated during the 2016 Kumamoto earthquakes, which included a magnitude-7.3 main shock. The geothermal power plant in Beppu continued operating without interruption.
According to Koichi Nishihara, the person in charge of the plant, steam used for power generation "condenses into hot water and is supplied to the hotel as onsen water."
Tatsuya Kurama, general manager of SUGINOI Hotel, describes geothermal power as providing "a sense of security" and serving as "a hedge against external changes."
Where Steam Sustains Livelihoods
Geothermal energy is also shaping the city, its people, and their livelihoods in unexpected ways. One such example: a rose-growing farm located at Shiraito Falls Onsen, a private facility perched on a hillside overlooking Beppu Bay, just a short distance from the city center.
Operated by Shinzo Sato, the bath is free-flowing (gensen kakenagashi), meaning hot spring water flows directly from the source into the bath without being recycled, diluted, or reheated.
Inside a nearby greenhouse, steam rising from the hot spring source keeps temperatures warm enough for roses to bloom even in winter. Their vivid pink petals seem to mirror the vitality and potential of the energy that nurtures them.
For Sato, geothermal heat also provides crucial stability. "If oil prices rise, it becomes really tough," he said. "But we haven't been affected by that."
Sato's example is just one of many. Across Beppu, geothermal energy is used in countless ways, from small family businesses to large-scale projects.
Beyond flowers, geothermal heat supports fruit farming, such as bananas and mangoes, and even animal rearing.
It's also used for heating and power generation, reflecting Japan's spirit of making the most of every resource.
Even food is cooked with hot spring steam, in a tradition known as jigoku-mushi, now a highlight of local tourism.
Potential and Challenges
If geothermal energy holds so much potential, why isn't it more widely used? The Japan Organization for Metals and Energy Security (JOGMEC) in Tokyo has explored this question.
"Japan has geothermal potential equivalent to 23 nuclear power plants," explained Kenichi Takahashi, head of JOGMEC's geothermal development department. He added that Japan excels in comprehensive engineering capabilities, from plant design to construction.
At the same time, significant challenges remain. Because geothermal energy is extracted from deep underground, exploration is complex, and development can take a decade or more. Careful and ongoing dialogue with local communities is also essential.
Takahashi stressed the importance of shared prosperity — an approach in which both developers and local regions benefit.
This is why regions like Beppu emphasize dialogue with local residents and building strong ties with the community.
Three Next-Generation Technologies
While challenges remain, Takahashi is excited about the future of three main technologies that could further broaden geothermal power's possibilities:
- Supercritical geothermal power: Extracting extremely high-energy supercritical water from depths of around 5,000 meters — far deeper than the conventional 2,000 meters.
- Closed-loop systems: Circulating liquid through underground piping to recover heat only, minimizing impacts on hot spring resources.
- EGS (Enhanced Geothermal Systems): Systems that artificially inject water into tight rock to fracture it, creating pathways for heat circulation.
Geothermal resources are found around the world, particularly along the Pacific Rim. If these technologies are commercialized, geothermal power has the potential to make a major contribution to sustainable development globally. Japan's Ministry of Economy, Trade and Industry and JOGMEC are strongly supporting these technological advances.
Beppu's Early Breakthrough
A century before today's debates over decarbonization and energy security, Beppu was already testing the potential of geothermal power.
According to a local plaque, Japan's first successful geothermal power experiment took place in Beppu Onsen on November 13, 1925.
The small, costly trial generated enough electricity to run one heater and about ten light bulbs. Yet it proved the concept: power could be produced reliably from heat drawn from the earth.
A century later, Oita now supplies a major share of the country's geothermal output, linking onsen culture to modern energy.
An Energy Source Rooted in Community
Japan's technical capability is a great advantage, but that is further amplified by its approach to holistic optimization, developing projects that harmonize with communities and the landscapes they depend on.
As next-generation geothermal technologies continue to advance, Beppu's relationship with steam offers a compelling model for how Japan can transform the earth's power into a sustainable energy future.
This article was written in collaboration with the Government of Japan.
Author: JAPAN Forward
