Climate change could be the most credible threat to humanity over the next century. As carbon dioxide emissions continue to rise, the world is looking for new and innovative technologies to remove CO2 from the atmosphere.

Carbon capture is poised to be a critical component in the fight against climate change. The idea emerged in the early 2000s and many climate activists were hopeful that the option would become the leading technology in climate mitigation. Unfortunately, this has not been the case. Carbon dioxide capture and storage has faced several massive challenges that have prevented it from widespread adoption.

Current carbon capture and storage technology

The idea behind carbon capture and storage is simple. Take carbon dioxide present in the atmosphere and place it in a benign location, such as an underground geological formation. Taking carbon out of the atmosphere will naturally lead to lower temperatures. There are two main categories to capture carbon dioxide from the atmosphere: point source and direct air capture.

Point source involves capturing carbon dioxide at the source where it is produced, such as a cement factory. Direct air capture involves capturing carbon dioxide directly from ambient air. Both methods use different capturing methods, such as membrane gas separation or absorption to capture carbon. Direct air capture technology is currently less advanced than point source technology. Both categories are necessary for climate mitigation and face similar problems.

The biggest issue that the carbon dioxide capture and storage is currently facing is that current methods are too expensive and ineffective. Energy costs often make it infeasible for a point source to be outfitted with carbon dioxide capture and storage technology. About two-thirds of the total cost of carbon capture and storage is attributable to carbon dioxide capture part of the process. Carbon capture also involves separating the carbon from the capture material once it is captured.

This step of the process can be expensive as it generally involves high energy costs. There are several ways to remove the carbon from the capture material and none of them are perfect. Many current carbon capture processes use amines, such as monoethanolamine. These materials are generally energy intensive, corrosive and do not capture carbon efficiently.

All hope is not lost for carbon dioxide capture, however. New materials could drastically improve carbon dioxide capture and storage technology. One material in particular, metal organic frameworks, may hold some of the answers to climate mitigation.

Metal organic frameworks may be the future of carbon capture

Metal organic frameworks are attractive candidates for carbon capture. This class of compounds is made up of metal ions or clusters that are bound by organic ligands to form structures. The ions or clusters act as joints, while the ligands act as linkers in the structure. The resulting materials have several properties that are perfect for carbon capture.

The material has the highest surface area of all known materials, as well as high porosity and selective absorptivity. Regeneration is also extremely important, as the material needs to be used multiple times for carbon capture. Selective absorption is extremely important as the material can be manipulated to select carbon dioxide over all other gases. The high surface area helps the material capture as much carbon as possible during the process.

Metal organic frameworks capture carbon dioxide via adsorption. This is the process where gas molecules adhere to the surface of a solid. This differs from absorption, where the gas molecules would permeate the surface of the solid. Metal organic frameworks are able to adsorb the carbon via physisorption or chemisorption, depending on the porosity and selectivity of the material. The carbon will stick on the metal organic framework as a thin film during the carbon capture process.

Once the carbon is adhered to the metal organic framework surface, the carbon can be removed via a pressure or temperature swing. The carbon will then be compressed and stored in the appropriate facility. The metal organic framework is then regenerated once the carbon is completely separated and can be used again in the process. Cost is still an issue even for this extremely promising material, but new research could change all that.

Researchers in Australia recently set a new standard for metal organic frameworks in carbon capture. The material, called M-74 CPT@PTMSP, significantly reduces the energy required for regeneration. Compared to current commercially available materials, the new material makes energy costs 45% cheaper. Additionally, stability is often one of the main issues that prevent metal organic frameworks from widespread adoption. The material was stable through 20 consecutive temperature swing cycles.

The next step for the research is to see if the material can be scaled up to become commercially viable. If they are successful, carbon dioxide capture will become significantly less expensive to implement. Their material could be the final push the carbon capture step of the process needs to push for widespread adoption. The fight against climate change will certainly be a multifaceted approach. Organic metal frameworks have the potential to contribute to climate mitigation.