RetroCO₂L

Project goals

Our project aims to retrofit existing recooling plants for direct air capture (DAC) of CO₂ using alkaline solutions coupled with electrochemical regeneration. Consequently, the overarching goal of RetroCO₂L is the experimental proof-of-concept of the DAC process for the use of a retrofitted industrial recooling plant as a CO₂ absorber. We want to experimentally demonstrate the process steps of CO₂ capture and release at TRL 3-4 and evaluate the process for the scale of industrial recooling plants. To achieve this overall goal, we have the following specific research objectives:

Research objective 1: Development of an experimentally validated scale-up model of the CO₂ absorber using basic solutions. The model forms the basis for the design and evaluation of industrial recooling plants for DAC.

Research objective 2: Development of a novel DAC process based on pH swing using neutral red as a redox-active pH-changing molecule in combination with a retention system. The goal is a low-energy electrochemical regeneration process that simultaneously overcomes challenges in terms of stability.

Research objective 3: Design, assembly, and operation of a scaled plant in a laboratory environment at TRL 3-4, as well as experimental proof of concept of the RetroCO₂L process at TRL 3. The proof of concept will be carried out using real air and in a realistic operating environment.

Research objective 4: Evaluation of the potential of RetroCO₂L in terms of capacity, costs, and feasibility for DAC.

The research project thus expands the range of available DAC processes. The particular innovation of the concept lies, on the one hand, in the retrofitting of existing infrastructure in an industrial environment, which leads to cost efficiency, alternative business models for otherwise decommissioned industries, and better social acceptance. On the other hand, a novel, low-energy process for the regeneration of the absorption solution is being developed.