Looking Back: Energy Storage Day 2026 – Energy Storage as the Key to a Flexible Energy System

On Wednesday, October 7, Energy Storage NL organized the twelfth edition of Energy Storage Day during the Vakbeurs Energie trade show in Den Bosch. This year’s event focused on the role of energy storage as the key to a flexible energy system.

The growth of renewable energy and the electrification of industry, transportation, and heating are causing increasingly large fluctuations in supply and demand. As a result, the need for flexibility is also growing. Energy storage can play various roles in this regard: from absorbing short-term peaks to bridging longer periods and making better use of renewable energy.

From residential neighborhoods to offshore

During Energy Storage Day, visitors gained insight from three innovation projects into the various ways in which energy storage can contribute to flexibility. Joule4Joule, OESTER, and RenewaFLEXNL each demonstrated—from a different perspective—which solutions are under development and which challenges still need to be addressed.

Joule4Joule demonstrated how excess energy from the summer can be used to provide heat in the winter. Simone Delić–Geerts of Enexis and Daan Verweij of Energie Samen discussed the technical, social, and organizational issues surrounding seasonal storage in residential neighborhoods. This involves not only technology but also new forms of collaboration, ownership, and governance.

OYSTER, presented by Catherine Eeckels of TNO, focused on the possibilities of offshore energy storage. Offshore storage can be linked to the growth of offshore wind energy and contribute to better utilization of renewable generation. In doing so, it can also help reduce bottlenecks in the power grid and prevent unnecessary grid expansions.

Finally, there was RenewaFLEXNL focused on long-duration energy storage (LDES). Bart Klootwijk of TNO demonstrated how long-duration energy storage can help balance supply and demand over longer periods. In addition to the technical possibilities, the business cases and the market and policy conditions for the further development of LDES were also discussed.

Different solutions, one flexible energy system

The three presentations made it clear that there is no single solution to the challenge of flexibility. Different forms of energy storage can each contribute to the energy system in their own way: from heat storage in residential areas and LDES to offshore storage.

In this way, the twelfth Energy Storage Day demonstrated that developing a flexible energy system requires a broad perspective on energy storage. Technological development, system integration, and the right framework conditions must all come together in this process.

Energy Storage NL would like to thank all the speakers and attendees for their contributions to a substantive and inspiring afternoon.