Formate for renewable energy storage (FRESH)

The aim of the project is to storage energy using CO2 products. The CO2 is captured, converted and used in a flow battery.

The overall aim of the FRESH project is to develop, operate and validate at TRL 4, an integrated, cost competitive process for conversion of CO2 to potassium formate (PF) using an electrocatalytic process powered by renewable electricity. The highly stable PF aqueous solution generated by the reactor will be stored safely for long periods in tanks. The subsequent conversion of the stored PF to electricity on demand will use a direct fuel cell system. The developed FRESH system will be sited at a single location for validation (partner HYSYTECH), and two key research objectives are CO2 conversion to PF (Electrolyser) and PF reconversion to electricity (fuel cell). More specifically, the FRESH project aims at:


  • The development, construction and operation of a prototype for renewable energy storage technology at TRL 4 that will convert green, carbon-neutral energy, water and carbon dioxide into a renewable fuel, potassium PF (PF) which will be used as energy carrier for electricity production. When the price of energy is high and renewables are scarce the fuel may be reconverted into electricity using a fuel cell system. The modular fuel cell STACK will run initially at 100 W. Higher power output can be achieved by combining the modular systems.


  • Investigation of CO2 source and renewable energy boundary conditions. Perform carbon capture testing and investigate the impurity effect on the CO2 capture process and CO2 to PF conversion. Investigate coupling the system to various renewable energy supplies to test robustness.


  • The integration of the CO2 electrolyzer and PF re-electrification module in one prototype system that realizes high energetic efficiency such that it is inherently market competitive, i.e. the production cost of the fuel in an upscaled scenario needs to be lower than the average market price, and the round trip efficiency should be higher than the state of the art of 25%.


  • Development of a cost-competitive, flexible and de-centralized energy storage solution via high-level financial cost-benefit modeling, taking into account capital expenses (CAPEX), operational expenses (OPEX) and expected revenues. The energy storage solution target is a capital cost of < €100/kWh, i.e. competitive to expected Li-Ion battery cost. From these considerations, the key performance targets for the individual technological building blocks will be determined.


The role of DTU CERE will be to perform laboratory experiments to optimize carbon capture for the utilization of CO2 in the flow battery.


Sebastian Nis Bay Villadsen
Senior Project Manager
DTU Chemical Engineering


Uffe Ditlev Bihlet
DTU Chemical Engineering