Seeking energy supply and decarbonization via geothermal heat: Akita University takes on challenge in Tajikistan

Whether in the heat of summer or the depths of winter, the temperature underground remains nearly constant just a few dozen meters below the surface. Heating and cooling systems that tap into this stable underground heat are drawing worldwide attention as a key technology for reducing dependence on fossil fuels and advancing the transition to a low-carbon society.

Since 2021, Akita University's Faculty of International Resource Sciences has been leading a project in Tajikistan, Central Asia, to develop energy systems that utilize underground heat. The project is not only demonstrating the feasibility of using underground heat in arid regions, where such applications have traditionally been considered challenging, but also contributing to local workforce development, institutional capacity building, and stronger ties between Japan and Tajikistan.

Science Portal interviewed project leader Fumiaki Inagaki (Dean of the Graduate School of International Resource Sciences and Dean of the Faculty of International Resource Sciences, Akita University) and Daizo Ishiyama, Leader of Groundwater Chemical Analysis Group (Specially Appointed Professor at the same graduate school) regarding their achievements to date and plans for future.

30-50% energy savings with ground source heat pump systems

Touching groundwater in summer feels cold, while touching it in winter feels warm. This is because the ground at depths of a dozen meters is less susceptible to surface temperature changes and is maintained at approximately 15 degrees Celsius throughout the year. This thermal energy is called geothermal heat and utilizing it as a heat source for air conditioning and heating is the "Ground Source Heat Pump (GSHP) system." Circulating antifreeze or groundwater through pipes buried underground (= ground heat exchangers), it adjusts indoor temperatures by releasing or absorbing heat.

Conventional air conditioners exchange heat with the outside air, making efficiency poor in midsummer or midwinter when temperature differences with indoor spaces are severe. On the other hand, GSHPs exhibit high energy efficiency by utilizing geothermal heat, which experiences little temperature fluctuation, as a heat source. According to Inagaki and colleagues, power consumption reductions of approximately 30-50% can be expected compared to conventional air conditioning and heating systems.

In Japan, it has been introduced at Akita City Hall and Haneda Airport and is also utilized in road snow-melting systems in cold regions. Amid demands for improving energy self-sufficiency, it is expected to be one of the technologies effectively utilizing renewable energy.

Some households consume 5 tons of coal in a single winter

Inagaki, who specializes in Central Asian politics and energy policy, has visited Tajikistan almost every year since 2007. What he witnessed on-site was a severe challenge where energy for winter heating was insufficient.

Surrounded by mountains and containing glaciers, Tajikistan covers approximately 96% of its power generation needs through hydroelectric power. However, in winter when it is extremely cold and heating demand is large, snowmelt is scarce and rivers freeze, causing power generation to plunge. Burning coal for warmth is widespread, and it is not uncommon for households to consume 5 tons in a single winter. Relying on old infrastructure from the former Soviet era, blackouts in winter occurred frequently.

What he thought would become an effective measure against such challenges was the utilization of geothermal heat. It can supply energy stably, and by lowering dependence on fossil fuels such as coal, carbon dioxide (CO₂) emissions can also be reduced.

Inagaki collaborated with Professor Hikari Fujii of Akita University Graduate School, a leading authority in geothermal heat research, and Ishiyama, who specializes in resource environment fields. In 2021, they launched the project "Construction of Decarbonized Heat Energy Supply System by Geothermal Heat Utilization" under the "Science and Technology Research Partnership for Sustainable Development (SATREPS)." SATREPS is an international joint research program conducted by the Japan Science and Technology Agency (JST) and the Japan International Cooperation Agency (JICA) as part of Official Development Assistance (ODA).

Analyzing groundwater components to serve water resource management

In this project, research is advancing in three major fields: "Long-term GSHP cooling and heating tests using demonstration plants," "Construction of geothermal heat potential maps utilizing artificial intelligence (AI)," and "System design including fundraising."

In the arid regions of Central Asia, groundwater levels are deep and soil moisture content is low, so there were no cases of geothermal heat utilization until now. However, investigating the groundwater distribution in Dushanbe, the capital of Tajikistan, revealed suitability for GSHPs. Being a basin, groundwater supplied from glaciers in surrounding mountainous areas was abundant, and underground temperatures were stable.

Analyzing data from demonstration experiments at plants, Inagaki stated: "For cooling energy-saving effects, we initially assumed 30% as the worst-case scenario, but we confirmed 41%. We learned that there is sufficient potential for geothermal heat even in Central Asia."

In addition, they analyzed groundwater at approximately 130 points around Dushanbe. Ishiyama explained: "In investigations started for geothermal heat utilization, data useful for water resource management was also gathered." Analyzing calcium amounts, carbonate components, and uranium concentrations contained in groundwater, data important for managing drinking water was obtained.

In Dushanbe, securing drinking water in response to population increases due to urbanization is necessary, and water resource management is also a challenge. However, until now, Tajikistan lacked groundwater analysis equipment, and situations prevented starting water quality surveys. The database regarding water quality established this time will also be useful for future public health and water administration.

Humanities and science researchers join hands toward social implementation

The project concludes in the spring of 2027. At the start, there were various difficulties, starting with travel restrictions due to the spread of COVID-19, and subsequently, logistics stagnated accompanying Russia's invasion of Ukraine. In addition, access to geological data necessary for research did not advance easily due to the complexity of Tajikistan's administrative systems. Through patient efforts and careful dialogue locally, they overcame obstacles one by one.

Through efforts spanning approximately six years, "the necessity of science education and human resource development for young generations" became visible, Inagaki and Ishiyama agree in unison. Young students possess motivation for learning, but they were forced into nation-building from scratch through independence from the former Soviet Union and subsequent civil wars. Basic educational environments supporting research have not been developed.

"We even heard voices saying they had never seen a thermometer," says Ishiyama. Using materials obtainable locally, they sometimes made handmade experimental equipment. Therefore, in the project, in addition to specialized technical guidance toward geothermal heat utilization, they continue to carefully provide online guidance regarding data management using spreadsheet software Excel and research methods, especially for young researchers.

"How to spread GSHPs in Tajikistan and how to establish them at the national energy policy level is important," says Inagaki, smiling wryly that "actually, geothermal heat is outside my specialty." It is rare for humanities researchers in fields such as political science and international relations to engage in SATREPS as project leaders. However, Ishiyama states: "To establish a path not only to technology transfer but also to social implementation, the presence of a researcher who can view the project from a sociological perspective holds great significance."

To create mechanisms actually used in society, it is necessary to comprehensively consider not only engineering, but also policies, systems, and human resource development. Researchers in humanities and sciences collaborating to become bridges between academia and practice aiming for social implementation is a major feature of this project. Even after the project ends, the two will continue working on the dissemination of GSHPs in Tajikistan in cooperation with international organizations and other entities.

Bonds forged through scientific and technological cooperation support bilateral relations

Through this project, Japan and Tajikistan have continued exchanges with local university, research institution, and administrative personnel beyond research and development of geothermal heat utilization technology, thinking about solutions for various challenges in Tajikistan together.

"In developing countries, it is not only cutting-edge technology that is demanded. Low-cost and easy-to-maintain basic technology is also important," Ishiyama emphasizes. Contributions through education in science fields where Japan excels and basic technical capabilities cultivated in the field are also significant. That accumulation leads to the building of trusting relationships.

In recent years, Japan has been advancing relationship strengthening with Central Asian nations, including Tajikistan. Last year, an investment agreement was signed with Tajikistan. Human networks and bonds of trust built through scientific and technological cooperation in this project will become important foundations supporting future relations between both countries.