Historic Japanese hot spring town turns to geothermal power

In a recent report by The Washington Post, Tsuchiyu Onsen, a historic hot spring town in the foothills of the Azuma Mountains near Fukushima City, has emerged as a pioneering example of how Japan can harness geothermal energy while preserving its cultural heritage.

For 1,400 years, travelers have flocked to this town at the base of the Azuma Mountains, near Fukushima City, to experience the famed healing waters of its hot springs. Over the centuries, the local community has relied on these waters to attract guests to their inns, bathhouses, and souvenir shops. However, nine years ago, the town's leaders took a bold step that few other hot spring towns in Japan dared to take: they constructed a geothermal power plant to convert their valuable hot spring water into a source of renewable energy. Today, Tsuchiyu Onsen serves as a model for how Japan might harness a plentiful source of clean energy while maintaining its cultural heritage. Despite possessing the world's third-largest geothermal energy reserves, Japan still relies heavily on imported fossil fuels for the majority of its electricity. Experts suggest that geothermal energy could potentially supply about 10 percent of Japan's power needs if fully utilized.

The government aims to triple geothermal energy output this decade, increasing it from 0.3 percent to 1 per cent of the country's electricity production. However, a major obstacle has been resistance from Japan’s hot spring industry. Most of the country’s geothermal energy reserves are located near its more than 3,000 hot springs, known as onsens, which hold significant cultural and tourism value. Many inn and bathhouse owners fear that geothermal development could damage their water sources, devastating their businesses. In Tsuchiyu Onsen, however, the residents believe they have found a way for geothermal power plants and onsens to coexist. “It’s crucial to preserve the onsen culture that is so integral to Japan’s identity,” said Rio Watanabe, the 22nd-generation owner of the Sansuiso Hotel in Tsuchiyu Onsen. 

“But we also need to promote clean energy in Japan, so we have to consider creating a new identity.” The Power Plant Next to the Spa Tsuchiyu Onsen residents reconsidered their stance on geothermal development following the 2011 Fukushima nuclear disaster, which devastated the local economy and pushed Japan to reduce its reliance on nuclear power. Hiroko Abe, 81, recalls the moment on March 11, 2011, when a 9.1-magnitude earthquake shook the ground beneath her. Abe, who runs a shop selling traditional wooden dolls and other souvenirs to hot spring visitors, remembers the earth shaking for six minutes at 2:46 p.m., causing merchandise to crash from the shelves around her. About 40 miles away, a 40-foot tsunami triggered a meltdown at the Fukushima Daiichi Nuclear Power Plant, forcing over 150,000 people to evacuate. 

Some of these evacuees sought refuge in Tsuchiyu Onsen. For almost a year, the town's inns were filled with evacuees waiting to return home. When they eventually left, the typical tourists didn’t come back. “Everything closed after the earthquake,” Abe recalled. “The issue wasn’t so much physical damage as it was the rumors about the nuclear plant and radiation. People just stopped visiting Fukushima.” Business plummeted. Five out of the town’s 16 inns went out of business. Local leaders were desperate for any solution that could generate revenue, draw visitors, and prevent Tsuchiyu Onsen from fading into obscurity. In the meantime, Japan temporarily shut down all of its nuclear reactors, which had accounted for nearly a third of the nation’s electricity and were central to its clean energy strategy. Energy regulators decided to shift focus to expanding wind, solar, and geothermal power. In 2015, Tsuchiyu Onsen took a bold step by developing a geothermal power plant—one of the first constructed under a relaxed set of environmental regulations established by the Japanese government after the earthquake.

It was also the first geothermal plant built in a Japanese national park. Across Japan, the onsen industry has largely united against geothermal development, fearing that large drilling projects could harm their water sources, destroy their businesses, and threaten an ancient cultural tradition. “We’re not against geothermal energy in principle, but we’re worried because there are currently no legal safeguards or compensation measures in place for the onsens,” said Yoshiyasu Sato, vice president of the Japan Onsen Association. “We want assurances from the government that they will provide compensation if there’s any actual damage or if there’s a drop in temperature or water levels.” Sato cited the example of the Takanoyu Onsen inn, which had to close temporarily after 135 years in operation because its water temperature dropped a year after a large geothermal plant was established nearby in 2019. 

He acknowledged that there’s no proof linking the temperature change to the geothermal plant, but the incident alarmed the onsen industry. In Tsuchiyu Onsen, however, the families owning inns and bathhouses collaborated with the local tourism association to create an energy company, Genki Up Tsuchiyu, and used their own money to build a geothermal plant. “The community came together to transition from nuclear energy to a source of power that felt safer,” said Watanabe, whose family has run inns in Tsuchiyu Onsen for over 300 years. “If it weren’t for the nuclear meltdown, the transition might not have been so smooth. There could have been more resistance.” The Potential of Small-Scale Geothermal Plants The geothermal plant in Tsuchiyu Onsen, which began operations in 2015, is small compared to the nuclear reactors that Japan shut down after the 2011 earthquake, or the oil, coal, and natural gas plants that still supply two-thirds of Japan’s electricity. 

The Fukushima Daiichi nuclear plant used to generate 4.7 gigawatts of electricity, powering millions of homes and businesses. In contrast, the Tsuchiyu Onsen geothermal plant generates 400 kilowatts of electricity, which Genki Up Tsuchiyu says is enough to power about 800 homes and supply warm water to a nearby shrimp farm. According to Kolbrún Ragna Ragnarsdóttir, an analyst at the International Renewable Energy Agency, small plants like this one are unlikely to transform Japan’s energy landscape on their own. However, they can play a crucial role in helping people understand and accept geothermal energy, paving the way for larger projects in the future. “This can help convince local communities throughout Japan that they can build similar projects without damaging their natural and beautiful environments,” she said. Japan’s volcanic islands sit atop thousands of shallow pockets of underground heat emanating from molten rock. When groundwater flows into these hot spots, it emerges as steam, providing ideal conditions for both hot spring baths and geothermal energy production. The Japanese government estimates the country has enough underground steam to generate about 23 gigawatts of geothermal power, though many of these locations are already home to onsens. 

Tsuchiyu Onsen is uniquely suited to combine its hot spring industry with geothermal power generation. Unlike most onsen towns, where each inn and bathhouse digs its own well to access hot water, Tsuchiyu Onsen has a single central source of spring water that supplies nearly all local inns and bathhouses. The geothermal plant was built on top of this existing water system without drilling new wells. Steam from the existing well heats a turbine to generate electricity, after which it is mixed with mountain water and channeled into onsen baths. Residents say they haven’t noticed any changes in the temperature or quality of their vital water. At the Ryokan New Ogiya, Shizue Endo still uses the water to make onsen tamago, a traditional onsen dish prepared by placing eggs directly into the hot spring water to slow-cook them until the whites have a distinctive custard-like texture. 

“Our water quality hasn’t been affected, so I’m not worried about the geothermal plant,” said Endo, who manages the inn. A Model for Other Onsen Towns Tsuchiyu Onsen could serve as a model for other onsen towns, according to Tomio Sakuma, renewable energy area manager for Genki Up Tsuchiyu. “It’s definitely possible if the local community supports it,” he said. However, he acknowledged that it would be more challenging for onsens without a centralized spring water source; in these cases, geothermal developers would likely need to drill a new steam source on the outskirts of town, which could spark opposition from onsen owners. Tsuchiyu Onsen’s geothermal plant employs a relatively recent technique for generating electricity that uses lower-temperature steam and requires less drilling, making it suitable for more locations with a reduced risk of disturbing hot springs. 

Since 2011, Japan has established over 70 geothermal power plants, with nearly all of them being similar to the one in Tsuchiyu Onsen. In contrast, only one large-scale plant has been constructed during this period: a 46-megawatt facility that generates about 100 times more power than Tsuchiyu Onsen’s plant. Larger projects often provoke more concern within the hot spring industry. “This spring water is the core of our business,” said Endo. Visitors are likely to notice any variations in water quality, as true onsen enthusiasts travel from inn to inn to experience the unique characteristics of each location's water.

Chiaki Takaoka, a visitor from the nearby hot spring town of Dake Onsen, notes that she prefers the water in her hometown. “The smell is different,” she said. “The water is milkier and makes my skin feel softer and smoother.” The value placed on onsen water is so high that a minor scandal in 2004 revealed some onsen inns were using tap water instead of hot spring water in their baths, or adding bath salts to alter the water’s appearance. This led to several inns closing in disgrace. “Japanese people have high expectations of onsens and believe in their healing properties,” said Mai Kato, deputy director of the Tsuchiyu Onsen Tourism Association. “While foreigners might not mind, it’s very important to Japanese people.” 

On a recent Thursday afternoon, visitors to Tsuchiyu Onsen relaxed in the smooth, sulfur-rich water that had recently emerged from the earth with enough force to power numerous homes. However, there was no indication of the nearby geothermal turbine at one of the town’s four public foot baths. Noriko Otsuki, 59, and her 92-year-old father, Riichi Fukada, dipped their feet into the foot bath. After Fukada’s health declined, they began visiting local onsens together. “It’s a good way for us to spend time together,” Otsuki explained. Across the street, 4-year-old Itsuki Takaoka tentatively touched a foot bath before deciding it was too hot. His mother, Chiaki Takaoka, hopes he will develop a love for onsens and help continue the tradition. “I hope he also falls in love with onsens and we keep this tradition alive,” she said.