the ocean like a wrung-out sponge

Our oceans already absorb a lot of CO2, but that could be done a lot better, American scientists thought. They have developed a new technology that gives the oceans’ CO2 storage a significant boost. Their trial off the coast of Los Angeles has just begun.

In the harbor of the American city of millions, there is a crazy ship full of pipes and tanks that is supposed to perform the miracle: with the new technology, the ocean would become a kind of CO2 sponge and thus slow down global warming.

A wrung-out sponge
Scientists of the University of California (UCLA) have been working on their project, called SeaChange, for two years. The aim is to use the ocean as a large sponge that is wrung out, explains Gaurav Sant. He is director of it Institute for Carbon Management (ICM) from UCLA.

More than 70 percent of the Earth consists of oceans. This makes them already the most important carbon sinks and a crucial buffer in the climate crisis. They absorb a quarter of all CO2 emissions and 90 percent of the heat generated in recent decades by increased greenhouse gas emissions. But the oceans are under pressure. They acidify and rising temperatures reduce their storage capacity.

From CO2 to lime
The UCLA researchers now want to increase that capacity again using an electrochemical process that removes large amounts of CO2 that are already in the seawater. They compare the process to wringing out a sponge. After that, the oceans can absorb more CO2 again, like a sponge absorbs water again. “If you can extract the CO2 that’s in the oceans, you’re essentially renewing their ability to absorb CO2 from the atmosphere,” Sant said.

To achieve this, technicians have built a floating mini-factory on a 30-meter long boat. The boat pumps up seawater and exposes it to electrically charged particles. The chemical reactions triggered by the electrolysis convert CO2 dissolved in the seawater into a fine white powder containing calcium carbonate. This substance is also found in, for example, lime, limestone and the shells of oysters and mussels.

Hydrogen for cars
This powder is thrown back into the ocean, where it remains in solid form and can store CO2 for tens of thousands of years. Meanwhile, the cleaned water is also pumped back into the sea where it can absorb more CO2 from the atmosphere.
According to the researchers, this process does not harm marine life, although more research is needed to confirm this. An additional advantage of the technology is that hydrogen is produced as a by-product. This gas can be used as fuel for cars.

First emit less
Every scientist involved in climate engineering emphasizes that people must first of all drastically reduce their CO2 emissions. But at the same time, that is probably not enough and other solutions should be looked at. For example, we previously wrote about artificial clouds or extra dust in the stratosphere. But a lot of research is also being done into techniques to store more CO2 in the earth or the water in order to keep our planet habitable.

Removing CO2 from the atmosphere may be crucial to be CO2 neutral by 2050, as it can offset emissions from aircraft, for example, but also cement and steel production, sectors in which it is difficult not to emit CO2.

Promising solution
But in order to achieve the climate goals, much more CO2 must actually be removed from the atmosphere. Estimates range from 450 billion to more than a trillion tons that must be removed by 2100, researchers already calculated in January. – and solar energy have increased,” said researcher Gregory Nemet. He is excited about UCLA’s SeaChange technology. “It fits into the category of promising solutions that are big enough to become climate-relevant,” said Nemet, a professor at the University of Wisconsin–Madison.

Isolating CO2 in mineral form in the ocean is clearly different from existing forms of CO2 storage, which extract the CO2 directly from the air. In addition, the gas must be pumped up and put underground, which is a complicated and expensive process. SeaChange is simpler and cheaper. Startup Equatic now wants to scale up the UCLA technology and prove that the method is commercially viable by selling carbon credits to manufacturers who want to offset their emissions.

Quickly operable
In addition to the ship in Los Angeles, there is another similar boat that is currently being tested in Singapore. Sant hopes that the results of both ships will soon lead to the construction of much larger floating factories capable of extracting thousands of tons of carbon from the oceans every year. The Americans are ambitious: they hope to have these factories operational within one and a half to two years.