SAFE-CO₂ – Switchable Adsorbers in a Structured Bed for Energy-Efficient CO₂ Capture

Challenge

The SAFE-CO₂ project aims to develop an energy-efficient technology for the direct capture of carbon dioxide (CO₂) from the air (direct air capture, DAC), thereby contributing to negative emissions and climate protection. While conventional processes require higher temperatures and greater amounts of energy for regeneration, SAFE-CO₂ pursues an innovative approach based on thermoresponsive adsorbent materials.

Objectives and project plan

The project focuses on special materials that can bind CO₂ on their surface. These adsorbents consist of polymers that undergo a change when heated. At relatively low temperatures (target: 70 °C), they release the previously adsorbed CO₂, allowing adsorption and release to be controlled selectively. The materials are designed to adsorb large amounts of CO₂, desorb it rapidly, and continue to function reliably over many operating cycles.

To enable large volumes of air to flow through the system with low resistance, the adsorbents are embedded in porous, sponge-like structures. These structures are known from membrane technology and provide a low pressure drop. At the same time, the heat supply is designed so that, as far as possible, only the adsorbents are heated. Part of the supplied heat is to be recovered and reused to further reduce energy demand.

Three partners with complementary areas of expertise are collaborating on the project. The Institute of Polymer Chemistry at Saarland University is developing the new adsorbent materials. The Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB is designing the modules and structures, while the Centre for Solar Energy and Hydrogen Research Baden-Württemberg is testing performance and developing suitable processes. In addition, the environmental and economic performance of the process will be assessed in comparison with existing solutions.

Impact

Overall, SAFE-CO₂ aims to demonstrate that the direct removal of CO₂ from the air is technically feasible, energy-efficient, and suitable for long-term use. The project thus makes an important contribution to future climate protection technologies. In the long term, the technology could help offset unavoidable emissions, provide CO₂ as a raw material for industry, construction materials, or chemical products, and enable sustainable value chains that promote climate-neutral processes and support the transition to a more environmentally compatible economy.