The US Department of Energy (DOE) will award up to $24 million for research into technology that captures carbon emissions directly from the air, replicating the way plants and trees absorb CO₂. (DE-FOA-0002481)

Although direct air capture of carbon dioxide (DAC) generally refers to the capture of CO₂ from ambient air, this FOA also considers the removal of CO₂ from partially concentrated air (e.g., building HVAC exhaust) and from natural fluids (e.g., the ocean and surface waters) that received their CO₂ directly from ambient air.

DOE is seeking innovative fundamental research in three topical areas:

1. Novel Energy Transfer Mechanisms for Regeneration of and Mass Transport in Direct Air Capture Systems;

2. Understanding Temporal Changes That Occur during Separations; and

3. Science-Driven Synthesis and Assembly of Innovative Materials for Direct Air Capture.

Energy Transfer Mechanisms. Most contemporary DAC approaches utilize energy poorly, as evident by second-law efficiencies for CO₂ separation of 1 to 9% (for comparison, post-combustion capture from coal exhaust attains second-law efficiencies greater than 20%). Hence, hypothesis-driven, fundamental research is sought to discover and elucidate novel mechanisms for efficient energy and mass transfer in DAC.

These mechanisms are normally affected by intermolecular attractions and repulsions, phase transitions, reversible- or irreversible-reaction chemistry, electron excitation or transfer, molecular diffusivities, and external forces. Applications focused on this topic must address one or both of the following categories:

• Mechanisms for highly selective energy delivery to natural or synthetic chemical separations systems containing captured carbon dioxide or its immediate derivative species and reaction intermediates. Exemplary mechanisms may employ reactive, electrochemical, magnetic, photo-induced steps or a synergistic confluence of such steps. Research focused solely on thermal mechanisms will not be supported.

• Mechanisms for preserving or redirecting heats of adsorption or solvation in a way that assists molecular transport or system regeneration after transport has occurred. Concepts that combine exothermic and endothermic stages to exchange thermal flux across a barrier are discouraged.

Temporal Changes. Materials and chemical processes involved in DAC can undergo chemical, physical, and/or structural changes over their operating lifetimes, for example due to unwanted chemical reactions and the accumulation of byproducts or impurities. Other factors include the evolution of separations media or materials from a nonequilibrium or metastable state toward an equilibrium state. Such changes can significantly affect the selectivity, efficiency, and rate of separation of a DAC system.

Hence, proposed research should yield a better understanding of the fundamental mechanisms of these changes, to provide a scientific foundation for more robust DAC systems that operate in complex and challenging environments.

Science-driven Synthesis and Assembly. Integrated data science and experimental research efforts with a clear scientific focus are sought to address the particular materials challenges of direct capture of CO₂ from dilute sources (e.g., ambient air, ocean and surface waters) and accelerate science-based synthesis and assembly of transformative materials with multiple properties designed for this purpose.

Applications must emphasize hypothesis-driven synthesis and assembly science to create innovative, robust materials that selectively capture CO₂ and either release or convert it into a useful material, fuel or chemical via non-thermal, low-energy processes. Because fundamental understanding and spatial and temporal control of synthesis, assembly, and related chemical pathways is essential to achieving this goal, proposed research also must incorporate in- situ and/or operando characterizations and high-fidelity determinations of structure dynamics and chemical processes.

Proposed research that does not emphasize fundamental understanding and control of synthesis and assembly pathways and non-thermal, low-energy CO₂ separation, capture, release, or conversion mechanisms via an approach that integrates data science techniques and advanced in situ and/or operando characterizations is outside the scope of this FOA and may be declined.

Proposed research that focuses on optimization of material properties via the use of high-throughput synthesis, test and evaluation processes or on optimization of existing direct air capture processes also is outside the scope of this FOA and maybe declined.

National laboratories, universities, industry, and nonprofit organizations will all be eligible to apply for this $24 million in total planned funding, which will be selected based on peer review. The Office of Basic Energy Sciences (BES) within the Department’s Office of Science, which is funding the effort, envisions awards both for single investigators and larger teams.

DOE supports the search for carbon removal solutions at both the basic and applied science levels. This funding announcement made through DOE’s Office of Science complements recent applied research efforts in direct air capture funded by the Department’s Office of Energy Efficiency and Renewable Energy and the Office of Fossil Energy.