Railway systems are positioned as a key means of transportation for reduction of the burden on the environment and are expected to contribute to the realization of railway infrastructure with enhanced energy saving, safety, and resilience from the viewpoint of achieving the Sustainable Development Goals (SDGs). We have been developing traction energy storage systems (TESS) equipped with its SCiB™ lithium-ion battery and supplying them for use in railway ground systems. The principle of the system, control method, and specialty of the converter will be presented. Also through sampling inspections of our SCiB™ battery modules for the actual usage, we have also confirmed that the TESS can achieve stable long-term operations. We have confirmed that the TESS supplied to the Yui Rail Line of Okinawa Urban Monorail, Inc. achieves high energy-saving performance, as well as ensuring an emergency power supply to propel rolling stock to the nearest station in the event of a wide-area blackout. The application of TESS to railway infrastructure is now beginning in both the Japanese and overseas markets.