A New York experiment is part of a commercial race to develop ocean-based technologies to extract carbon dioxide from the atmosphere, reports Nature.
World’s first carbon-removing beach
Bonnie Chang squints at a tube of sediment collected beneath the shallow waters off North Sea Beach — about a two-hour drive from New York City. She’s looking for green mineral crystals that her team added to the sand last year. If all goes as planned, these olivine crystals will cause the ocean to absorb more carbon dioxide from the atmosphere — a climate solution that could potentially be scaled up around the globe.
This is one of the first field trials of a concept known as ocean alkalinity enhancement — essentially using antacids to help the ocean digest CO2. The two-year experiment is run by Vesta, a start-up climate company based in San Francisco, California, with enthusiastic support from local community leaders. Just metres down the beach, a newly installed welcome plaque proclaims that visitors are about to step onto “the world’s first carbon-removing beach”.
Chang, a chemical oceanographer leading the field work for Vesta, isn’t so sure just yet. Looking at the clear sediment tube, she is disappointed to discover a distinct layer of olivine crystals buried beneath about 10 centimetres of beach sand.
“The olivine is deeper than I was expecting,” she says. “I was hoping it would stay on top and mix in.” That might signal trouble because it could slow down a series of reactions that could — along with many other factors — determine whether the beach lives up to its promise.
Ocean alkalinization
Vesta is one of many companies investigating unusual solutions for removing carbon from the atmosphere. Global temperatures are quickly approaching 1.5 °C above preindustrial levels and nations have yet to rein in emissions. Models suggest that the world would need to pull billions of tonnes of CO2 from the air each year by mid-century to keep temperatures from rising beyond 1.5–2 °C — a goal countries agreed on with the 2015 Paris climate agreement. Scientists, entrepreneurs and investors are increasingly looking to the oceans for solutions, which cover 70% of the planet and already soak up more than one-quarter of the greenhouse gases emitted each year.
In this area, ocean alkalinization has garnered increasing interest, with scientists focusing on ideas ranging from mineral supplements to the direct removal of CO2 from seawater using electrochemistry. This is partly because of ocean alkalinization’s nearly limitless potential, but also owing to the fact that it relies on fairly predictable chemistry and physics rather than more complex biological solutions, such as fertilizing phytoplankton in the ocean or industrial-scale seaweed farming. Indeed, if properly applied, ocean alkalinization technologies wouldn’t change life in the ocean much at all, say proponents.
“It’s almost too good to be true,” says Katja Fennel, an oceanographer at Dalhousie University in Halifax, Canada, who is preparing for a field trial involving a different technology in Nova Scotia later this year. “But doing this at a scale that is relevant for carbon removal — that’s a daunting challenge.”
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Source: Nature
