The maritime sector is facing a major transition from fossil fuels to fuels based on renewable energy sources in the coming years. However, there is still a need to find solutions to store renewable energy. Energy storage will play a key role in the green transition as it will enable a more stable and reliable integration of renewable energy sources such as solar and wind into the existing electricity grid.


The project aims to develop an innovative energy storage solution based on Iron Flow technology that can provide reliable long-term energy to maritime vessels and the grid using non-toxic, environmentally friendly, cost-effective and non-combustible iron-based electrolytes. Innovation in the use of water-soluble iron coordination complexes will allow operation at neutral pH. This will represent a major non-iterative step that will bypass energy losses and the need to rebalance cells as a consequence of coating and hydrogen circulation. This will favourably simplify stack construction considerably.

Extensive test trials will be performed on a large-scale commercially available iron flow battery (75 kW / 500 kWh) to obtain a great understanding of the system and improve battery operation. In addition, a control strategy for effective operation (efficiency and reliability) will be developed.


The project aims to attain a <100 €/kWh cost for the flow battery upon scaling-up.


Siemens Gamesa Renewable Energy A/S

DTU Technical University of Denmark

SDU University of Southern Denmark


Siemens Energy A/S 


Financed By:

EUDP (14.500.000 DKK)

Totalbudget: 14.524.553,00 DKK

Grant amount: DKK DKK

Contact person

Hans Jørgen Brodersen

Hans Jørgen Brodersen
Senior Project Manager
Tlf: +45 2688 0228