World - An Electrifying Approach to Carbon Capture
A new sodium-ion “battery” promises an environmentally friendly method of sequestering carbon in the ocean, but experts remain cautious.
As the race to reduce greenhouse gases in the atmosphere intensifies, a group of researchers at the University of Calgary is using electricity to enhance seawater’s ability to store carbon.
The group is developing an instrument, dubbed PEACH (Practical Electrochemical Air Capture and Hydrogen), that uses an electrochemical cell, analogous to a lithium-ion battery, to capture alkaline sodium ions from salt water.
Although a prototype is still being designed, University of Calgary electrochemist Arthi Gopalakrishnan said the PEACH module will be a book-sized device made of nickel-plated steel that could be bolted onto others in an array.
These arrays could be lowered more than 500 meters into the ocean to gather ions, then raised to release them as sodium hydroxide at shallower depths, creating an “alkalinity pump” from deep water to the surface.
Alkaline surface waters draw carbon dioxide (CO2) from the atmosphere, eventually converting it to bicarbonate, which can securely store carbon in the ocean for more than 10,000 years. A by-product of the ion exchange is hydrogen, which could be stored as a fuel. The group will present their research at AGU’s Annual Meeting 2023 in San Francisco.
Building Blocks
“We don’t have other technologies that could scale up at this level.”
Although PEACH technology has yet to advance beyond a laboratory setting, geochemist Steve Larter, who first developed the concept, said the scalability of the technology is part of what makes it so exciting.
“Think of it as a LEGO brick,” Larter said. “One LEGO brick will do so much. You can stack hundreds together, and you’d have a bigger system.” This modularity is what attracted Gopalakrishnan to work on the project. “Our system is very flexible,” she said. “We don’t have other technologies that could scale up at this level.”
PEACH technology, Larter said, could be deployed extensively in the ocean, perhaps on floating platforms. “You might imagine something that has wind turbines or solar panels on it to generate power; electrochemical cells, and then pumps and pipes to move the water around.”
However, PEACH could also be used at a smaller scale on land, for example, in the reservoirs of brine produced by oil and gas drilling. PEACH cells, Larter said, could add carbon dioxide to the brine before it is reinjected underground.
