Energinet has asked Ea Energy Analyses to analyse the benefits and main drivers for the installation of electricity storage units in the Danish power system. This will supplement the technology aspects in the recent Technology data Catalogue on Energy Storage.

Electric storage has experienced a growing interest in the last years due to a general cost drop, its manifold potential applications in the energy sector and a wide array of technological options. The attractiveness of electric storage is motivated by its ability to provide multiple grid-related and market services.

This report introduces the pivotal technical features of three promising storage technologies (batteries, flywheels and thermal storage) and highlights their suitability to create value from flexibility and provide system services. Through an analysis of demonstration projects, pilot installations and literature findings the role of storage is reviewed and discussed in both the Danish and the international context.

Several demonstration and commercial projects have been carried out worldwide. Batteries are the storage type with the most far-reaching applications; among them, Li-ion technologies have gained a remarkable attention due to their technology readiness level and a sizeable cost reduction in the past years.

Batteries (and – more generally – storage) can create value from flexibility and provide a set of different services in power systems and potentially combine them into a single business case. Applications include energy-only market activities such as arbitrage and system balancing but also a series of grid-supporting services.

After going over the main features of the Danish electricity markets – with a focus on the provision of ancillary services – opportunities for value-stacking (utilizing opportunities across markets) are identified and examined for the year 2025 at the transmission grid level.