Make oceans ‘vast carbon sinks’

Speeding up a natural process through “electrochemical weathering” could be used to absorb carbon in oceans and reduce the impact of climate change, U.S. researchers say.

Our technology dramatically accelerates a cleaning process that Nature herself uses for greenhouse gas accumulation,” Harvard University PhD candidate Kurt Zenz House said in a release Thursday.

The scheme is ambitious, costly and has its own risks, the researchers said. It would require building dozens of facilities on coasts of volcanic rock.

Oceans have absorbed about one-third of the carbon dioxide that humans have produced, but the process is very slow, the journal Environmental Science and Technology said on its website. And the more acidic oceans are, the less CO2 they can absorb.

House and colleagues from Harvard and Pennsylvania State University said they found a way to remove hydrochloric acid from the ocean and neutralize it using silicate from volcanic rocks.

That increases the ocean’s alkalinity, so it can store more atmospheric CO2 as bicarbonate, already the most common form of carbon in the oceans.

“That means we may be able to safely and permanently remove excess CO2 in a matter of decades rather than millennia,” House said, describing the process as accelerating the natural system to industrial rates.

In nature, carbon dioxide is dissolved by fresh water, forming a weak acid. The acid is neutralized as water filters through rocks, producing an alkaline solution of carbonate salts, the release said.

Eventually the water reaches an ocean, where the alkaline solution holds the dissolved carbon until it eventually becomes a sediment.

The researchers’ process uses other chemical processes to minimize potential side effects.

There are other plans to sequester carbon in oceans, but this proposal reduces acidity.

House and colleague Harvard professor Michael J. Aziz said more research is needed on the process.

As well as House and Aziz, the researchers include House’s brother Christopher H. House, associate professor at Pennsylvania State University and Daniel P. Schrag, director of the Harvard University Center for the Environment.

Environmental Science and Technology published the research.