[Image above] Microencapsulated sorbent materials may provide a better means of carbon capture. Credit: Torsten Hofmann; Flickr CC BY-SA 2.0


Developing strategies to mitigate carbon emissions is one of the most pressing challenges of our time. Irreversible damage has already been done to the planet’s environment, atmosphere, and ecosystems. Without change, scientists predict, global warming will continue until disastrous changes have been made to the planet.

Can sufficient changes be made in humanity’s behavior?

Can we build a green economy atop those changes?

If real change can be made, will it be too little, too late?

While many speculate, no one can predict the answer—but we try anyways.

One pathway is through policy changes, which are edging in the right direction. United States regulations are slowly cinching the thick carbon emission waistlines of power plants, one of the biggest sources of greenhouse gases. According to the White House website, the power sector contributes almost 40% of the U.S.’s carbon emissions.

Once regulations are enacted, however, the second piece of the puzzle is compliance. Regulation changes require power plants to equip themselves with carbon-capturing technologies, processes that are laborious and/or expensive. Cheaper, safer, and more feasible solutions are needed to ensure compliance and enact serious change.

So, in addition to new policies and regulations, we need new technologies, too, to reach those goals.

(Like these nanoporous carbon–nitrogen and carbon–suflur compounds, courtesy of James Tour’s Rice University research group.)

ACerS Fellow, member, and awardee Jennifer A. Lewis is among those pioneering new technologies for change. Lewis, the Hansjörg Wyss Professor of Biologically Inspired Engineering at Harvard’s School of Engineering and Applied Sciences, co-led a team of scientists at Harvard University and Lawrence Livermore National Laboratory that has devised microencapsulated sorbent materials for carbon capture and sequestration.

The new materials suck up carbon dioxide cheaper, safer, more energy-efficiently, and than current strategies, which largely rely upon energy-intensive techniques that use caustic amine chemicals. Alternative existent techniques use zeolites, which are safer but also more cost-prohibitive.

Smoke Stack from Sugar Factory in Belle Glade Florida

Credit: Kim Seng; Flickr CC BY-NC-ND 2.0

“Microcapsules have been used in a variety of applications—for example, in pharmaceuticals, food flavoring, cosmetics, and agriculture—for controlled delivery and release, but this is one of the first demonstrations of this approach for controlled capture,” Lewis says in a Harvard Gazette article.

The team’s new approach bypasses expensive or hazardous substances, instead finding inspiration from the kitchen—sodium carbonate (a.k.a., baking soda) is the key ingredient.

The scientists call their new technique microencapsulated carbon sorbents (MECS), a way of packaging the sorbent materials into small round beads.

Lewis’s team produced MECS using a double-capillary microfluidic assembly. The device had the advantage of being able to precisely control each component of the material—“a carbonate solution combined with a catalyst for enhanced CO2 absorption, a photo-curable silicone that forms the capsule shell, and an aqueous solution,” according to the news release.

“Encapsulation allows you to combine the advantages of solid-capture media and liquid-capture media in the same platform,” Lewis says. “It is also quite flexible, in that both the core and shell chemistries can be independently modified and optimized.”

In addition to the benefits of safety, cost, and efficiency, the MECS also have a nearly-limitless shelf life and capture carbon reversibly, according to the release. Heating the materials causes release of captured carbon dioxide, allowing easy sequestration through complementary methods.

“MECS provide a new way to capture carbon with fewer environmental issues,” says Roger D. Aines, co-leader of the study and leader of the fuel cycle innovations program at Lawrence Livermore National Laboratory, in the release. “Capturing the world’s carbon emissions is a huge job. We need technology that can be applied to many kinds of carbon dioxide sources, with the public’s full confidence in the safety and sustainability.”

Scientists are now working on tweaking the work to bring it to scale. If successful, MECS also may be able to help other carbon-spewing industries become more green, including cement and steel production. (To read about additional efforts towards greener cement, click here.)

The paper, published in Nature Communications, is “Encapsulated liquid sorbents for ​carbon dioxide capture” (DOI: 10.1038/ncomms7124).