Grid-connected Hybrid batteries

Challenge

In the energy sector, Denmark has now reached a level of green electricity coverage (particularly from wind power) that makes it necessary to use stationary (electrical) energy storage—in synergy with Demand Side Management (DSM) and sector coupling—to avoid both overcapacity and the curtailment of wind and solar power plants.

There are already a number of different technologies for storing electrical energy, with battery systems and pumped storage power plants being the most well-known. However, no technology has yet been able to establish itself in the stationary storage market. While battery systems are currently mainly used for mobile applications (e.g., electromobility) and short-term grid services (< 15 minutes), their investment and operational costs for long-term energy storage (> 1 day) are still too high.

Solution

The approach to the problem in the project is the hybridization (system integration) of at least two different (electrical) energy storage systems, which, when hybridized, have a value that exceeds the sum of each of them individually. In the simplest case, this could be a combination of battery systems from two different manufacturers due to limited production capacities. However, the project focuses more on technical hybridization to improve and optimize the system parameters.

The project is co-financed by the Ministry of Education and Research.

Impact

Specifically, a lithium battery system with high power (kW) but low capacity (kWh) (as required for grid services) can be hybridized with a redox flow battery system with high capacity (kWh) and low power (kW) in order to leverage the application and cost advantages of the different technologies without being limited by their respective disadvantages.