Scientists at Lawrence Livermore National Lab have developed a way to get a triple win – removing carbon from the atmosphere, reducing the acidity of the world’s oceans and producing hydrogen.
"We not only found a way to remove and store carbon dioxide from the atmosphere while producing valuable H2, we also suggest that we can help save marine ecosystems with this new technique," says Greg Rau, a visiting scientist at Lawrence Livermore and senior scientist at UC Santa Cruz.
The team demonstrated, at laboratory scale, a system that uses the acidity normally produced in saline water electrolysis to accelerate silicate mineral dissolution while producing hydrogen fuel and other gases. The resulting electrolyte solution was shown to be significantly elevated in hydroxide concentration that in turn proved strongly absorptive and retentive of atmospheric CO2.
Further, the researchers suggest that the carbonate and bicarbonate produced in the process can be used to mitigate ongoing ocean acidification, similar to how an Alka Seltzer neutralizes excess acid in the stomach.
"When powered by renewable electricity and consuming globally abundant minerals and saline solutions, such systems at scale might provide a relatively efficient, high-capacity means to consume and store excess atmospheric CO2 as environmentally beneficial seawater bicarbonate or carbonate," says Rau. "But the process also would produce a carbon-negative ‘super green’ fuel or chemical feedstock in the form of hydrogen."
Other methods of removing carbon from the atmosphere and storing it are costly, using thermal/mechanical procedures to concentrate molecular CO2 from the air while recycling reagents – a process that’s also cumbersome, inefficient and expensive.
"Our process avoids most of these issues by not requiring CO2 to be concentrated from air and stored in a molecular form, pointing the way to more cost-effective, environmentally beneficial, and safer air CO2 management with added benefits of renewable hydrogen fuel production and ocean alkalinity addition," Rau said.
Further research will determine optimum designs and operating procedures, cost-effectiveness, and the net environmental impact/benefit of electrochemically mediated air CO2 capture and H2 production using base minerals.
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