Posted in | Pollution | Sustainability

Unique, Affordable CO2 Capture Materials Identified for Coal Power Factories

Researchers at the University of Pittsburgh’s Swanson School of Engineering have formulated a computational modeling technique that may help to accelerate the identification and design of new carbon capture and storage materials for use by the country’s coal-fired power factories. The hypothetical mixed matrix membranes would provide a more cost-effective solution than current approaches, with an anticipated cost of less than $50 per ton of carbon dioxide (CO2) removed.

Depiction of a metal-organic framework (HKUST-1) embedded in a polymer matrix to be used as a membrane for efficient gas separations. (Kutay Sezginel)

The research team—led by Christopher Wilmer, assistant professor of chemical and petroleum engineering, in partnership with co-investigator Jan Steckel, research scientist at the U.S. Department of Energy’s National Energy Technology Laboratory, and Pittsburgh-based AECOM —reported its findings in the Royal Society of Chemistry journal Energy & Environmental Science (“High-throughput computational prediction of the cost of carbon capture using mixed matrix membranes,” DOI: 10.1039/C8EE02582G).

Polymer membranes have been used for decades to filter and purify materials, but are limited in their use for carbon capture and storage. Mixed matrix membranes, which are polymeric membranes with small, inorganic particles dispersed in the material, show extreme promise because of their separation and permeability properties. However, the number of potential polymers and inorganic particles is significant, and so finding the best combination for carbon capture can be daunting.

Dr. Wilmer, Head of Hypothetical Materials Lab, Swanson School of Engineering, University of Pittsburgh.

According to Dr. Wilmer, the scientists developed upon their widespread research in metal-organic frameworks (MOFs), which are extremely porous crystalline materials developed via the self-assembly of inorganic metal having organic linkers. These MOFs, which can store a higher volume of gases than traditional tanks, are very versatile and can be created from a range of materials and tailor-made with specific properties.

Dr. Wilmer and his team studied prevailing databases of hypothetical and real MOFs for their research, resulting in over one million potential mixed matrix membranes. Next, they compared the predicted gas permeation of each material with published data, and assessed them based on a three-stage capture process. Variables such as capture fraction, flow rate, pressure and temperature conditions were enhanced as a function of membrane properties with the goal of finding specific mixed matrix membranes that would yield an affordable carbon capture cost.

The potential inferences for the Wilmer team’s research are incredible. Although coal-generated power plants in the U.S. alone presently represent just 30% of country’s energy portfolio, in 2017 they contributed the largest share of 1,207 million metric tons of CO2, or 69% of the total U.S. energy-related CO2 emissions by the whole U.S. electric power sector. (Source: U.S. Energy Information Administration.)

Our computational modeling of both hypothetical and real MOFs resulted in a new database of more than a million mixed matrix membranes with corresponding CO2 capture performance and associated costs. Further techno-economic analyses yielded 1,153 mixed matrix membranes with a carbon capture cost of less than $50 per ton removed. Thus, the potential exists for creating an economically affordable and efficient means of CO2 capture at coal power plants throughout the world and effectively tackling a significant source of fossil fuel-generated carbon dioxide in the atmosphere.

Dr. Wilmer, Head of Hypothetical Materials Lab, Swanson School of Engineering, University of Pittsburgh.

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