Ammonia2HeatStorage – Development of a long-term storage system through the combination of CLC and “green” ammonia by means of Membrane Distillation

In order to increase the volatile share of renewables in the energy supply mix, the development of efficient energy storage technologies is becoming increasingly important. The requirements for such technologies are high flexibility, high freedom from losses and, in particular, compactness, i.e., storing as much energy as possible with small system volumes. In the recent past, chemical looping combustion (CLC) for long-term energy storage has been researched. The advantage of a CLC storage system is that, unlike, for example, sensible heat storage systems, heat can be stored chemically from several days or weeks to months without loss. Up till now, the CLC technology has been mostly used in combination with fossil fuels.

The CLC technology uses an oxygen carrier (OC), a metal, which is reduced/oxidized in cycles. The reduction can be achieved using biogas (CH4), Hydrogen (H2) or other fuels (e.g., synthetic gas, solid coal, NH3, etc.) while the oxidation is done with air. For most of the OCs, both reactions are exothermic, and heat can be extracted from both. The aim of the project was to explore the viability of the CLC technology using the “green” NH3 recovered from waste streams via Vacuum Membrane Distillation-VMD for the storage of renewable energies. The main success of the project was a “proof of concept” of a lab-scale CLC prototype reactor which could be operated with NH3.