Regeneration of Carbon Dioxide Sorbents by Joule Heating: Improving Energy Efficiency and Net Carbon in Direct Air Capture
Nathan Ellebracht | 21-FS-017
The high energy requirements for regeneration of direct air capture (DAC) sorbents, which remove CO2 directly from the atmosphere, are a major factor in process cost and inhibit deployment. Regeneration is often accomplished with steam stripping, which results in substantial energy requirements (3-6 GJ/tCO2), the use of fossil-derived fuels for energy, and in decreased sorbent lifetime due to leaching and degradation. The use of renewable electrical energy to regenerate DAC sorbents would decrease the over carbon negativity of a DAC process. By integrating the capability of joule heating into the support material, efficient local heating may be achieved integrated directly into the sorbent material itself and without requiring the use of steam or other thermal energy.
In this project, we developed porous ceramic supports for aminopolymer-based DAC sorbents for regeneration via joule heating. We utilized direct ink writing (DIW) 3D printing to generate hierarchical porous ceramic structures and investigated the effects of particle size and processing conditions. We incorporated commercial aminopolymers into the porous ceramic materials to generate hybrid polymer/ceramic sorbents. An optimal polymer loading range was identified and top performing materials achieved competitive amine efficiencies under direct air capture conditions (410 ppm CO2). We validated thermal sorbent regeneration and capacity retention with cycling.
This study strongly aligns with a cross-cutting array of Lawrence Livermore National Laboratory (LLNL) and DOE missions and core competencies. This is central to the Engineering the Carbon Economy Director's Initiative and the Energy and Resource Security Mission Focus Area in developing cost-effective and energy efficient direct air capture technologies. It supports the Core Competency in Advanced Materials and Manufacturing through advancement of porous ceramic material processing and additive manufacturing capabilities. The inclusion of climate security as a LLNL Mission Focus Area makes this a potentially critical technology. There is a growing suite of projects and expertise in direct air capture at the lab, and this small project brought in a number of new capabilities supporting efforts in these important and growing areas. The integration of this technology across competencies and focus areas and the synergy between advancing material development expertise and climate and energy security applications solidify the key role it plays in LLNL and DOE/NNSA's missions.
Publications, Presentations, and Patents
Ellebracht, N. "Regeneration of direct air capture CO2 sorbents by joule heating," LLNL Laboratory for Energy Applications for the Future (LEAF) Meeting Seminar, virtual, Oct. 19, 2020.
IL-13540: Porous Ceramic Supports for Resistively Heated Hybrid Gas Sorbents. Non-provisional patent application submitted (June 16, 2021).