Energy storage technologies in a Danish and international perspective

In many ways this whitebook can be seen as an update of the report “Status and recommendations for RD&D on energy storage technologies in a Danish context”1, which was published February 2014 – and then again, this whitepaper is somewhat different in structure and noticeably different in content as well.

The present report is based solely on information available in literature. It mentions why and how the report was prepared, defines and delimits the concept of “energy storage” as used in the work and gives an overview of the most significant development trends of modern energy systems since publication of the above-mentioned report in 2014.

The whitepaper points out major application areas and describes the status of selected storage technologies (with an eye to Danish competences) as well as future application and export potentials. As a natural consequence, the current worldwide market situation for storage technologies is summarized and a projection of the market development over the years to come is cautiously sketched.

Four storage technologies are studied closely in the present report: Batteries, Electrochemical storage, Thermal storage and Mechanical/Thermomechanical storage. It is interesting to note how the use of batteries has grown since 2014 and how the demand for batteries seems to increase dramatically for yet another period of years driven by several new applications and an increasing population, who can afford buying battery-driven devices including vehicles.

In the report Li-ion, Na-S, Na-NiCl and flow battery technologies are described, but other chemistries are included, because they represent new, promising types of batteries potentially able to take over after the Li-ion era. The report finds that for electrochemical energy storage still some prudent development work has to be done to reach a sufficiently user-friendly state in terms of economy and technical performance.

However, electrochemical storage has outstanding properties and fits very well into the sustainable energy system. It links the primary generation of electricity to a variety of highly valuable products and services in the energy sector - and in the materials sector as well. Thermal energy storage is already a large and important storage area with a huge installed capacity found in hot water containers in buildings and in district heating networks.

About 50% of energy consumption is demanded as heat. The demand for cold is also significant, very energy consuming and expected to grow in the years to come. New thermal energy storage techniques therefore need to be developed and demonstrated, and existing techniques – in particular for large scale storage - should be further developed and refined.

Denmark has a strong position in development of heating systems and already a considerable export, which could be expanded based on new technologies. Within mechanical energy storage, flywheel technology is pointed out as a promising topic showing production in Denmark. Furthermore, materials and production techniques have benefitted from the development of rotor blades for wind turbines, since the same or very similar composite materials are in use.

In addition, flywheels show performance characteristics to meet some difficult challenges in the sustainable energy system. The whitepaper finally gives proposals for a revised policy and regulatory framework, which can support energy storage in the energy system, as well as recommendations for actions to consolidate Denmark´s position within energy storage production and export.