Extra-High Voltage Grid Battery for Kyushu

KS Energy and Hitachi have agreed to collaborate on the development and operation of an extra-high voltage battery energy storage system (BESS) in Kumamoto, alongside joint development of power trading capabilities to support grid stability and carbon neutrality in the Kyushu region.

Addressing grid balancing in a renewable-heavy region
The Kyushu region has experienced rapid growth in renewable energy capacity, particularly solar generation. Because renewable output fluctuates with weather conditions, maintaining the supply-demand balance has become increasingly complex. Periods of excess generation have led to frequent output curtailment, highlighting the need for flexible balancing resources.

At the same time, Japan’s policy framework is shifting from the Feed-in Tariff (FIT) to the Feed-in Premium (FIP) model. Under FIP, generators must actively manage electricity sales in competitive markets rather than relying on fixed tariffs. This transition increases the importance of aggregation and advanced trading capabilities to optimize asset value and stabilize the grid.

Extra-high voltage battery energy storage system
The planned project involves development and operation of a grid-connected battery energy storage system in the extra-high voltage range within Kumamoto Prefecture. By charging and discharging in response to real-time supply-demand conditions, the BESS will provide balancing power to the regional grid.

KS Energy will manage core operational functions, including electricity price forecasting, charging and discharging scheduling, facility control and monetization through participation in electricity markets. The initiative represents the first instance in Japan of a bank subsidiary’s renewable energy business company undertaking a grid-scale battery project at extra-high voltage level.

KS Energy was established in January 2024 with full investment from Higo Bank, part of the Kyushu Financial Group, and aims to contribute to regional energy circulation and grid stability.

Joint project development and technical support
Hitachi will provide early-stage development support and technical expertise. This includes grid connection discussions with transmission and distribution operators, regulatory procedures with relevant ministries, business feasibility assessments and project management covering equipment design, procurement and installation.

The Hitachi Group will also supply power conditioning systems (PCS) manufactured by Hitachi Energy. Ongoing support is intended to ensure stable long-term operation of the storage facility.

Power trading and aggregation functions
In parallel with the physical storage project, the companies will collaborate on enhancing power trading capabilities. As renewable penetration increases, aggregators—entities that coordinate distributed energy resources to balance supply and demand—are becoming essential.

KS Energy is considering adoption of a power trading support system under development by Hitachi. Within Hitachi’s Lumada 3.0 framework, the HMAX by Hitachi AI solution suite is being positioned to optimize battery asset operation and maximize market value. By combining operational data from physical assets with advanced AI models, the system aims to improve forecasting accuracy and trading strategy execution.