Supporting the Development of Japan's First Underground Data Center Utilizing an Existing Tunnel – Transforming Existing Infrastructure in Kobe City, Hyogo Prefecture into a Next-Generation Infrastructure Hub
Pacific Consultants Co., 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 as a supporting partner in Japan's first *1 underground data center project utilizing an existing tunnel (hereinafter referred to as "the project") , which is being promoted in Kobe City, Hyogo Prefecture, by Mitsui Fudosan Co., Ltd., Kumagai Gumi Co., Ltd., and Getworks Co., Ltd. as the project operators. 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 tunnel, such as its naturally cool environment, seismic resistance, and physical security.
Conceptual image of an underground data center utilizing an existing tunnel (Courtesy of Mitsui Fudosan Co., Ltd.)
■Background of the project
The project will utilize a former belt-conveyor tunnel facility, *2extending 14.5 km and linking the mountains and the sea of Kobe, and was used to transport earth and sand for land development until September 2005. This tunnel has served as infrastructure supported the urban development of Kobe City, including the development of housing complexes, 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 adoption of generative AI, demand for GPU (Graphics Processing Unit) servers with high processing capabilities is increasing. In Japan, securing land and power for data centers, as well as developing facilities capable of handling the significant heat generated by GPU servers, has become a major challenge. Recognizing that the characteristics of underground space make it well suited to the environment required for data centers in the AI era, the three project operators are advancing this project.
| Characteristics of the existing tunnel | Benefts for use as a data center |
|---|---|
| Year-round cool temperatures of 15°C to 20°C | Reduces cooling load for high-heat-generating GPU servers and improves energy efficiency. |
| High seismic resistance as an underground structure | Enhances resilience against natural disasters and external risks. |
| Restricted access due to its enclosed underground environment | Provides a high level of physical security for the safe storage and operation of critical data. |
Project Concept Image (Courtesy of Mitsui Fudosan Co., Ltd.)
■ Technical support for evaluating the characteristics of the existing tunnel
To leverage the characteristics identified by the three project operators for use as a data center, technical studies are essential for converting the existing structure to a use other than its original purpose. Our company leverages the expertise it has gained through involvement in the entire infrastructure lifecycle, from planning and investigation to design, construction supervision, and maintenance, to provide support for both project feasibility studies and design.
■ Overview of the project
| Location | Kobe City, Hyogo Prefecture |
|---|---|
| Facilities for use | Approximately 3 km (with an area of approximately 17,000 m²) of a former belt-conveyor tunnel facility linking the mountains and the sea of Kobe (total tunnel length: 14.5 km) |
| Location and Environment | Most of the facility is located more than 40 m underground, with year-round temperatures of 15°C to 20°C |
| Facility Overview | Installation of containerized data center equipment within the existing tunnel (targeting a maximum power receiving capacity of 20 MW in the future) |
| Cooling system | Water-cooling system utilizing recirculated groundwater |
| Start of operation | End of 2027 (initial development, planned) |
| Project operators | Mitsui Fudosan Co., Ltd. and Kumagai Gumi Co., Ltd.: Development of a data center site utilizing underground space Getworks Co., Ltd.: Operation of the containerized data center |
| Supporting partnre | Pacific Consultants Co., Ltd..: Support for project feasibility studies and design support |
| Contractor | Kumagai Gumi Co., Ltd. (planned) |
■Supporting the effective utilization of existing infrastructure as a social infrastructure service company.
In Japan, a vast amount of infrastructure developed during the period of rapid economic growth is reaching the time for renewal. At the same time, underground spaces throughout the country, such as disused tunnels and former mine sites, hold potential for new applications.
The concept of a "circular economy," which promotes the long-term use, reuse, and repurposing of resources, is increasingly being adopted in the building sector. Rather than demolishing existing infrastructure and replacing it with new facilities, the project seeks to extend the life of existing infrastructure through a change of use. Our company believes that this initiative extends the concept of adaptive reuse, which is gaining traction in the building sector, to infrastructure and can be regarded as a form of “circular infrastructure.”
The concept of a "circular economy," which promotes the long-term use, reuse, and repurposing of resources, is increasingly being adopted in the construction sector. Rather than demolishing existing infrastructure and replacing it with new facilities, this project seeks to extend the life of existing infrastructure through a change of use. Our company believes that this initiative extends the concept of adaptive reuse, which is gaining traction in the building sector, to infrastructure and can be regarded as a form of “circular infrastructure.”
*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 research conducted by Mitsui Fudosan Co., Ltd.).
*2 A tunnel used by Kobe City to transport soil for land development until September 2005.
Reference: Press Release issued by Mitsui Fudosan Co., Ltd. on October 6, 2026.
https://www.mitsuifudosan.co.jp/corporate/news/2026/1006/