Power generation from hot springs Tsuchiyu Onsen, Fukushima, utilization of sleepy resources
Japan is a land of hot springs, and power generation utilizing the heat of the source has begun to operate in major hot spring areas. Hot spring power generation is a type of geothermal power generation, which is one type of renewable energy. It is a dormant resource that is attracting attention from the perspective of decarbonization and energy security. It also leads to “local production for local consumption” of electricity. I looked into the site of hot spring power generation.
About 30 minutes by car from Fukushima Station on the Tohoku Shinkansen. In early September, when I visited the Tsuchiyu hot spring village in northern Fukushima Prefecture, where celebrities go incognito, I found a small power generation facility with an area of about 20 square meters in operation deep in the mountain path. Near the small "power plant" surrounded by forest, a hot spring with a temperature of about 60 degrees Celsius flows, and the steam shines against the deep green. Tsuchiyu Onsen, which lost one-third of its lodging due to the nuclear power plant accident caused by the Great East Japan Earthquake in 2011, is a top runner in hot spring power generation that was among the first to work on renewable energy.
■ Use of high-temperature steam
When I twisted the lever of the tank that draws out the hot spring from the basement, hot steam, not hot water, spouted out. This is the source of Tsuchiyu Onsen. The temperature is 130 to 150 degrees Celsius, which is higher than other hot spring areas, and not only hot water but also steam is generated. 150 liters of hot springs per minute are supplied to inns and homes by mixing with spring water from nearby Kurosawa-numa. At Tsuchiyu Onsen, one of the four sources is used for power generation.
An employee of the long-established inn "New Ogiya" said, "As individuals become more conscious of energy, efforts to turn hot springs into energy will benefit the city." In order to make the most of power generation, it is first separated into hot water and steam. It heats the gas that drives the generator's turbine in two stages, each through a separate pipe. The point is to use heat energy without waste.
With the aim of recovering from the earthquake at Tsuchiyu Onsen, hot spring power generation was launched immediately. Since ancient times, hot springs have been used to provide energy for heating in winter, so it was easy for citizens to imagine. Genki Up Tsuchiyu (Fukushima City) was established in 2012 with funding from local hot spring cooperatives and others.
There was concern about the impact on the hot water veins that flow to the inn. For this reason, the whole town researched the mechanism of geothermal power generation. There are two major power generation methods. The "flash method", which is the mainstream in Japan, generates electricity by directly rotating a turbine with steam extracted from a heat source that boils under reduced pressure (flash) underground. While it can generate electricity on a large scale, it uses a high-temperature heat source of 200 degrees or more, so it is necessary to dig deep into the stratum, increasing the possibility of damaging the veins. It also increases development costs.
The other is the "binary method". Since the gas is heated in two stages to generate electricity, it can generate electricity even at the temperature of the source. The power supply is small, but it is easy to take in even in hot spring areas. Tsuchiyu Onsen adopted this method. Approximately 1 billion yen was invested to start operation of a 400-kilowatt power plant in 2015.
■ To fund urban development
A total of about 1,000 people can stay at the ryokan in the center of the hot spring village. It is a scale that can cover about 70% of this power. Currently, it sells electricity to Tohoku Electric Power under the feed-in tariff (FIT) system, earning more than 100 million yen annually. The money is used for urban development, such as regenerating vacant houses as tourist bases. Furthermore, the hot water used for power generation is used to grow shrimp. Tourists can catch shrimps and grill them on the spot. It is circulated as a new source of funds.
As a model case for generating profits from hot spring power generation, we have received a series of inquiries from electric power companies and Kyushu, which has many hot spring towns. Takayuki Kato, CEO of Genki Up Tsuchiyu, said, "About half are considering commercialization, and their seriousness is increasing." Tsuchiyu Onsen will also consider power supply within the region after the end of the 30-year FIT.
Hot spring power generation can be introduced if certain conditions are met, such as requiring 50 liters or more of hot water per minute, which is equivalent to the amount of hot water emitted from an inn. There are many hot spring areas such as Kusatsu and Beppu, where the temperature of the source is lower than that of Tsuchiyu and exceeds 100 degrees, making it suitable for the binary system. Hot spring power generation can accumulate know-how to generate small-scale "local production for local consumption" electricity.
Unlike solar power and wind power, geothermal power generation such as hot spring power generation is regarded as a promising renewable energy that can stably generate power regardless of the weather or time of day. Although Japan ranks third in the world in terms of geothermal resources, it ranks tenth in the world in terms of installed power generation capacity, and is not being used effectively. It pales in comparison to countries such as the Philippines, which have less geothermal resources than Japan.
However, the government also regards geothermal as one of the important power sources. The support system by the Japan Oil, Gas and Metals National Corporation (JOGMEC) has also been enhanced. Over the next few years, the "potential survey" for development will expand to include digging a hole of about 500 meters to check the underground temperature and grasping the strata from the sky with a helicopter. I'm trying
Now that energy security has been shaken by Russia's invasion of Ukraine, the focus of energy security is how to make the best use of the country's resources. Hot spring power generation has great significance as a place to nurture the technology, in order to enhance the superiority of Japan's geothermal technology.
■ Issues in local consensus building
Construction projects for geothermal power generation are expected to progress in Japan and overseas from 2022 onwards. Among them, hot spring power generation is expected to be a distributed power source for local production for local consumption. There are also issues such as local consensus building.
Steam erupts from the pipe that draws out the source of Tsuchiyu Onsen (Fukushima City)
Tsuchiyu Onsen was relatively easy to get a consensus from the residents that the nuclear power plant accident had a direct impact on the city's survival and that renewable energy should be introduced. Hot spring power generation requires enough hot springs to supply the power of a Japanese inn. It is necessary to invest in facilities after obtaining the consent of the town that makes a living from the hot springs. "It is said that it costs 100 million yen per kilometer to develop a power transmission network, and the cost balance with the power supply system is also a focus." (Genki Up Tsuchiyu)
Adopting the binary system also has the advantage of being able to introduce hot spring power generation at low cost. The condition is that a certain amount of both steam and hot water can be collected to warm the gas in two stages. Depending on the hot spring area, there are cases where the heat source is only water and steam cannot be collected.
Kato, CEO of Genki Up Tsuchiyu, explains that it is difficult to predict the future after the FIT ends. "With the FIT system still in place for the next five to 10 years, it is difficult to see whether a system will be put in place to live up to the FIT, so it is difficult to predict whether power generation will be able to get into full swing or end with the FIT," he said.
In order to win the understanding of the local people, it is also necessary to contribute to the local economy. In the future, Tsuchiyu Onsen wants to launch hot spring power generation itself as a unique tourism content. Against the backdrop of growing interest in energy, we are actively proposing school excursion programs to elementary and junior high schools as part of renewable energy education, and are considering tours for the general public to see power generation facilities.
The global competitive environment for geothermal power generation is also changing.
In Japan, where geothermal resources are abundant, the flash method, which is suitable for large-capacity power generation, was developed first. Nearly 70% of the global market for geothermal power generation facilities is held by Japanese companies such as Mitsubishi Heavy Industries. Looking overseas, there are many places such as Turkey where the underground temperature is not as high as in Japan. Binary systems, which enable efficient power generation even with low-temperature heat sources and small power generation facilities, are predominant.
In fact, the growth of the binary system is large in the United States. According to the U.S. National Renewable Energy Laboratory (NREL), the amount of geothermal heat introduced from 2010 onwards will be 70,000 kW for flash systems, and 540,000 kW for binary systems, about eight times higher.
If power generation equipment is limited to the binary system, the composition will change completely, such as Omat Technologies of the United States becoming the world's top. Omat's power generation equipment was also adopted at Tsuchiyu Onsen. In 2013, Mitsubishi Heavy Industries made Turboden, an Italian binary manufacturer, a subsidiary, and will focus on the binary power generation business in the future.
In other Japanese companies, the tendency to shrink is conspicuous. Kobelco Compressor (Shinagawa, Tokyo), a subsidiary of Kobe Steel, announced in May that it will stop selling micro binary generators. This is because the supply of refrigerants used in generators is expected to decrease due to environmental regulations. Kawasaki Heavy Industries was also involved in related equipment, but withdrew in order to concentrate management resources on the hydrogen business.
