RIKEN R-CCS and LRZ Strengthen Collaboration toward Improving Energy Efficiency in HPC — Joint Advancement of Direct Liquid Cooling, Thermal Optimization, and Waste Heat Recovery Technologies —

The RIKEN Center for Computational Science (R-CCS) and the Leibniz Supercomputing Centre (LRZ) signed a Memorandum of Understanding (MoU) at the opening ceremony of SCA/HPCAsia 2026 Osaka. The MoU aims to promote the sharing of practical knowledge, including technical information and operational data, toward realizing next-generation supercomputing systems with high energy efficiency and resource-efficient operation.

Through the exchange of the MoU between Dr. Satoshi Matsuoka, Director of RIKEN R-CCS, and Prof. Dieter Kranzlmüller, Chairman of the Board of Directors of LRZ, the two centers will promote the exchange of experience and data related to the operation and design of direct warm-water cooling, thermal optimization, waste heat recovery, and energy-aware scheduling of computational jobs. This collaboration will enable comparative analyses of computing technologies, while jointly advancing tools for operational monitoring and job management, with the goal of establishing energy-conscious operational methodologies.

While supercomputers provide large-scale computational capabilities, their high power consumption during operation remains a significant challenge. Both R-CCS and LRZ employ direct liquid cooling technologies in their high-performance systems. Compared to air cooling, direct liquid cooling offers higher cooling efficiency and contributes to reduced operational energy consumption. In addition, the waste heat generated by these systems has the potential to be reused for heating nearby offices and buildings.

R-CCS is currently developing the successor system to Fugaku, while LRZ is working on the next-generation system following SuperMUC-NG. Although Japan’s “FugakuNEXT” and Germany’s “Blue Lion” differ in their system concepts, both are expected to integrate accelerators, including those from NVIDIA. While this integration enables the application of artificial intelligence (AI) methods, it also presents challenges in terms of increased power consumption.

In current cooling water operations, RIKEN employs water at approximately 15°C, whereas LRZ operates with warm water temperatures of up to 40°C. Through purpose-driven monitoring, LRZ has pursued improvements in the energy efficiency of high-performance computing resources. These efforts optimize hardware and computational job operations from an energy perspective and support smoother execution of scientific computing codes. In addition, adjustments to building facilities play a key role in supporting energy-efficient HPC operation in conjunction with liquid cooling technologies.

Based on this MoU, the two centers will primarily collaborate on the following topics:

This collaboration is scheduled to continue through 2030. In addition, the two centers plan to share technical resources and promote exchanges among support staff and HPC operations personnel through workshops, mutual visits, and exchange stays. In parallel, discussions will be held to further expand the scope of cooperation and strengthen the partnership between the two centers.