CAMBRIDGE, MASS.
Ateam of researchers from Harvard University and Pennsylvania State University have developed a new means to facilitate carbon dioxide removal from the atmosphere and to safely harbor it in the ocean for storage. Potentially a solution for reversing global warming, the researchers say the new process improves upon previous carbon sequestration technologies because the new process decreases the acid content of the oceans and may prove beneficial to coral reefs.
“Essentially, our technology dramatically accelerates a cleaning process that Nature herself uses for greenhouse gas accumulation. The technology involves selectively removing acid from the ocean in a way that might enable us to turn back the clock on global warming,” Kurt Zenz House, a graduate student in Earth and planetary sciences at Harvard University, told the Environmental Science and Technology journal in early November.
The research team includes House; House’s brother, Dr. Christopher H. House, associate professor of geosciences at Penn State; Dr. Daniel P. Schrag, the director of the Harvard University Center for the Environment and professor of Earth and planetary sciences; and Dr. Michael J. Aziz, the Gordon McKay Professor of Materials Sciences at Harvard.
The team has explained that their technical solution stems from a process called natural silicate weathering. In natural silicate weathering, carbon dioxide from the atmosphere dissolves in fresh water and forms weak carbonic acid. As the water flows through the soil and rocks, the carbonic acid changes into a solution of alkaline carbonate salts. This water eventually flows into the ocean and increases ocean alkalinity. While an alkaline ocean is able to hold dissolved carbon, an acidic one will release the carbon back into the air. The more weathering that occurs, the more carbon is transferred to the ocean where some of it eventually becomes part of the sea bottom sediments.
“HCl (Hydrochloric acid) is electrochemically removed from the ocean and neutralized through reaction with silicate rocks. The increase in ocean alkalinity resulting from the removal of HCl causes atmospheric CO2 (carbon dioxide) to dissolve into the ocean where it will be stored primarily as HCO3 (bicarbonate) without further acidifying the ocean,” according to the researchers.
Fully implementing the process would require the construction of dozens of facilities similar to large chlorine gas industrial plants, on volcanic rock coasts around the world. The researchers caution that while they claim their approach for reducing global warming is possible, the implementation of it would be expensive and highly ambitious. The plan also poses some environmental risks that require additional study. “
This work shows how we can remove carbon dioxide on relevant timescales, but more work is needed to bring down the cost and minimize other environmental effects,” says Dr. Christopher H. House.
–Ronald Roach
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