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Japan’s Geothermal Farms Revitalising Communities

Strawberries, mangos, shrimp, bean sprouts, melons, and other farmed products thrive in the warmth of Japanese hot springs.

By Greg Goodmacher
November 14, 2022

Onsen towns and farmers in remote areas of Japan are harvesting the warmth and the power of geothermal resources to counter various rural woes in some of the coldest regions of Japan. Producing food with geothermal resources not only provides jobs but it also reduces fuel costs. 

Owani in winter | Photo: Marushichi

OWANI ONSEN'S HOT SPRING FOOD PRODUCTS

The natural onsens of Owani, Aomori, have been soothing bathers for over eight centuries. And the springs have been nutritionally supporting residents since farmers learned to cultivate bean and buckwheat sprouts with hot spring water almost four centuries ago.  

Owani was also an oft-visited ski resort until the popping of Japan's economic bubble. That sorely affected the local economy. Now, residents are capitalizing on the demand for Owani's trademarked heirloom sprouts for revitalisation. With that in mind, locals are teaching their traditional farming techniques to selected newcomers. 

Farmers grow the sprouts in deep furrows on the floors of darkened greenhouses. The sprouts drink only the hot spring water sprinkled upon them. Pipes circulating thermal water through the soil warm the sprouts, which grow crispier and longer than most other varieties. Farmers pick and rinse the 30 to 40 cm-long sprouts with spring water.  

Freshly picked onsen bean sprouts | Photo: Owani Town

Long ago, locals presented Owani's sprouts to samurai lords who came for the baths. Now, the descendants of those gifted bean sprouts are spreading the town's name across the nation. Gourmets and top chefs fortunate enough to obtain the golden sprouts add their zestiness to fried dishes and miso soups. Tokyoites search for Owani bean sprouts in shops specializing in Aomori products. Locals consume 70% of the harvests. "Onsen bean sprout shabu shabu" is a popular meal in Owani.  

Owani's hot spring waters also produce another high-demand specialty. The Marushichi Company uses local soybeans and rice yeast to make its signature "onsen miso" in tubs warmed with mineral water pumped from the earth. The fragrant steamy rooms stay at 20°C despite harsh winters.  

Photo: Owani Town

SNOW COUNTRY MANGOS

Mangoes used to be tropical fruit. But now, in the famed ski resort town of Yuzawa, Niigata, and in at least two areas of Hokkaido, yellow and orange mangoes are bringing colour and sweetness to wintery landscapes. For farmers in these agricultural areas, winter is financially challenging. Deep heavy snows cover the fertile soil for months.  

When mango entrepreneur President Hiroyuki Nakagawa of Noraworks explained his plan to grow winter mangos in Obihiro Hokkaido, his neighbours and local business people considered him foolhardy.  

But chasing his dream, he rented land with a natural hot spring that wells up from 1,000 meters beneath the surface. The 42°C water heats his greenhouses. A 20 cm layer of bark blankets the soil. His mango trees are flourishing. Outside temperatures can drop to minus 25°C, so insect and mold infestations are non-existent, eliminating the need for chemicals. Nakagawa stores snow underground. Then, he cools the greenhouses in summer by piping meltwater through them.  

Between December and January, Nakagawa harvests between 4,000 to 7,000 mangos. Mangos with a sugar content of 15% or higher are trademarked "Silver Suns.” Nakagawa markets his mangos in exclusive Tokyo supermarkets and online, selling out by mid-January. In Japan, his specialty mangos start at around 6,000 yen but can go above 50,000 yen. Hong Kong's Super City supermarket started selling limited numbers of Silver Sun Mangos in December 2021. Nakagawa is currently experimenting with lychee, with pineapples and papaya next in line.  

Hot spring grown melon

Meanwhile, researchers in Tsugaru, Japan, are testing new melon farming methods. Like many other regions of Japan, Tsugaru is struggling to stop youth from leaving for prominent cities and rejecting strenuous farming jobs. Thus, melon harvests, typically harvested once yearly, have declined.  

However, recent agricultural experiments are pointing toward an economic revival. Using advanced hydroponics, IoT sensors, cameras, and greenhouses warmed with hot spring water, researchers are harvesting melons three times yearly, and yields are greater. In addition, inexperienced farmers can use smartphones to access heat, light, humidity, and other data on their smartphones and make necessary adjustments.   

SHARING THE HEAT

Japanese geothermal power plants often support farmers. For example, Mori Town, Hokkaido’s power plant channels clean but hot water into neighbouring greenhouses where locals grow tomatoes and cucumbers despite freezing conditions. 

In another case of sharing geothermal heat, Beppu City farmers grow chrysanthemums in greenhouses heated with 120°C steam during winter. Hot water flows from those greenhouses into nearby community bath facilities. 

Cooking with Onsen | Photo: Greg Goodmacher

ONSENS FOR FISH

Various freshwater fish and marine creatures grow faster when cultivated in warm water. Onshore onsen-heated aquaculture projects are booming. Fish farmers raise Tilapia, pufferfish, eel, shrimp, and abalone in pools warmed with hot spring water.  

COOKING WITH ONSENS

Onsen-assisted farming and cooking are trendy today. Numerous towns attract visitors with free cooking facilities for steaming eggs, yams, shellfish, fish, greens, and other onsen-produced ingredients. Savouring these warm, steamy hot-spring dishes with the taste and aroma of mineral waters is a treat.  

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