Carbon dioxide (CO2) capture from the fossil fuel combustion exhaust of industrial plants remains a key area of Earth-based sustainability research and development. Technology for CO2 capture and sequestration has long been regarded as critical for reducing atmospheric CO2 emissions; however, the CO2 capture step is still very energy inefficient and expensive.
Technology breakthroughs that can reduce the cost of CO2 capture are still needed for plant operators to implement CO2 sequestration globally, especially where there are no regulatory drivers. By utilizing both the unique flow and separation physics of fluids in microgravity, as well as techniques for the synthesis of novel capture media, the International Space Station (ISS) may serve as a valuable platform to advance CO2 capture technology.
As an example, Houston-based startup Cemsica sought to leverage microgravity conditions on the ISS to improve the synthesis of novel nanoporous membranes for the separation of CO2 from combustion exhaust streams or air. Cemsica’s membranes contain porous nanoparticles that enable precise separation of CO2 from other gases. Gravity affects the ordering of particles at the nanoscale, and the synthesis of the membrane material in microgravity could result in nanoparticles with more consistent pore size and shape—potentially improving the CO2 separation performance of the membranes.
Through their ISS U.S. National Laboratory investigation, Cemsica aimed to resolve current manufacturing challenges to develop lower-cost membranes with improved properties. Insight gained from such research could not only improve the production of nanoporous membranes on Earth but also lay the foundation for future in-orbit manufacturing and use.
Another closely related, active area of research is the conversion of CO2 to useful organic or inorganic materials, including attempts to mimic plant photosynthesis using novel materials and systems to capture CO2 from air. In microgravity, not only is the behavior of biological systems altered, but the molecular forces of diffusion, surface tension, and capillarity tend to dominate fluid flow phenomena in contrast to greatly diminished gravity-induced mechanisms such as sedimentation, or buoyancy-induced convection in thermal systems.
Therefore, there is ample opportunity for innovation in the areas of novel liquid solvents, solid sorbents, membrane or other materials, microfluidic reactor systems, or hybrid combinations of these technologies that could yield significant breakthroughs in CO2 capture and utilization technology for direct application in industrial plants.
To learn more about how investigators are using the unique conditions on the ISS National Lab to advance meaningful sustainability research and development, see the Upward feature “Spaceflight Studies for a Sustainable Future.”