We will support the development of Japan's first underground data center utilizing existing tunnels – transforming existing infrastructure in Kobe City, Hyogo Prefecture into a next-generation infrastructure hub.
Pacific Consultants Co., Ltd., Ltd. (Headquarters: Chiyoda-ku, Tokyo; Representative Director, President Executive Officer: Satoko Okano; hereinafter referred to as "our company") will provide support for the feasibility study and design of Japan's first *1 underground data center project utilizing existing tunnels (hereinafter referred to as "this project"), which is being promoted by Mitsui Fudosan Co., Ltd., Ltd., Kumagai Gumi Co., Ltd., and GetWorks Co., Ltd. as the project operators in Kobe City, Hyogo Prefecture. With the planned start of operations (initial development) at the end of 2027, our company is providing technical support, leveraging its expertise as a social infrastructure service company, regarding the characteristics of the existing tunnels, such as their cooling properties, seismic resistance, and physical safety.
Image of an underground data center utilizing existing tunnels (Photo courtesy of Mitsui Fudosan Co., Ltd.)
■Background of this project
This project will utilize a former belt conveyor tunnel facility *2 that connected the mountains and the sea of Kobe over a total length of 14.5 km and was used to transport earth and sand for construction until September 2005. This tunnel is an infrastructure that has supported the urban development of Kobe City, including the development of housing complexes and industrial parks and the reclamation project for Kobe Airport, and its underground space has the potential to be utilized for new purposes.
Meanwhile, with the rapid spread of generative AI, demand for GPU (Graphics Processing Unit) servers with high computing power is expanding. In Japan, securing land and power for data centers, as well as developing facilities to handle the high heat generation of GPU servers, are becoming challenges. The three companies involved in this project have focused on the fact that the characteristics of underground space are suitable for the environment required for data centers in the AI era, and are promoting this project.
| Characteristics of existing tunnels | Significance of using it as a data center |
|---|---|
| Cool temperature of 15°C to 20°C throughout the year | Reduce the cooling load on high-heat-generating GPU servers and improve energy efficiency. |
| High seismic resistance as an underground structure | Enhancing our ability to respond to natural disasters and external risks. |
| A closed environment where access from the outside is limited. | Ensuring high physical security for the safe storage and operation of critical data. |
Business concept image (provided by Mitsui Fudosan Co., Ltd.)
■ Technical support for the analysis of tunnel characteristics
To leverage the characteristics identified by the three companies for use as a data center, technical considerations are essential for converting existing structures to uses different from their original purpose. our company utilizes our expertise gained from being involved in the entire lifecycle of infrastructure, from planning and surveying to design, construction supervision, and maintenance, to provide support from both the business feasibility study and design perspectives.
■ Overview of this project
| Location | Kobe City, Hyogo Prefecture |
|---|---|
| Facilities for use | Of the 14.5km total length tunnels that were formerly used for a conveyor belt connecting the mountains and the sea in Kobe, approximately 3km in length and covering an area of approximately 17,000m² |
| Location and Environment | Most of the area is located at depths of approximately 40 meters or more underground / The ambient temperature is 15°C to 20°C throughout the year. |
| Facility Overview | Install containerized data center equipment within existing tunnels (aiming for a maximum power receiving capacity of 20MW in the future). |
| Cooling method | A water-cooling system that recycles groundwater. |
| Start of operation | End of 2027 (initial development, planned) |
| business operator | Mitsui Fudosan Co., Ltd. and Kumagai Gumi Co., Ltd.: Development of data center sites utilizing underground space GetWorks Co., Ltd.: Operation of containerized data centers |
| Partner companies | Pacific Consultants Co., Ltd..: Support for business feasibility studies and design support |
| Builder | Kumagai Gumi Co., Ltd. (planned) |
■Supporting the effective utilization of existing infrastructure as a social infrastructure service company.
In Japan, the vast amount of infrastructure developed during the period of rapid economic growth is reaching the end of its lifespan, and at the same time, there are underground spaces throughout the country, such as tunnels and former mine sites that have served their purpose and are expected to be put to new use.
The concept of a "circular economy," which involves using resources for extended periods and reusing or repurposing them, is spreading to the construction sector. This project, which involves continuing to use existing infrastructure by changing its purpose rather than demolishing and rebuilding it, is, in our company opinion, an initiative that extends the concept of adaptive reuse (reuse through conversion of use), which is becoming increasingly popular in the construction sector, to infrastructure—a concept akin to "circular infrastructure."
our company will continue to support the steady progress of this project, and will technically support the efforts of businesses to connect existing infrastructure to its next role. By providing consistent support from potential assessment to commercialization studies and design, we will contribute to the realization of sustainable and resilient infrastructure and a digital society.
*1 This is the first commercial data center project in Japan to utilize existing tunnel space and be developed for the purpose of providing services to external customers (as of September 2026, according to Mitsui Fudosan Co., Ltd.).
*2 A tunnel that Kobe City used to transport soil for construction until September 2005.
Reference: Mitsui Fudosan Co., Ltd. Press Release dated October 6, 2026
https://www.mitsuifudosan.co.jp/corporate/news/2026/1006/