A team of scientists from UCLA University (University of California Los Angeles) has been working for two years on this project aimed at combating global warming, called SeaChange.
Their goal is “to use the ocean as a big sponge“, explained to Agence France Presse, Gaurav Sant, director of the Carbon Management Institute (ICM) of UCLA. The latter explained that the seas covering most of the Earth are the best climatic ally, because the ocean absorbs more than a quarter of all carbon dioxide (CO2) emissions and 90% of the heat they have emitted in recent decades.
However, the ocean is in danger, as it is acidifying and rising temperatures are reducing its absorptive capacity. The scientific team wants to increase this absorption capacity, thanks to an electrochemical process that removes the CO2 contained in seawater.
“If you can remove the carbon dioxide from the oceans, you’re essentially renewing their ability to capture additional carbon dioxide from the atmosphere.“, explained Gaurav Sant, director of the Carbon Management Institute.
The latter explained that it is like squeezing a sponge to recover its absorption power. The engineers therefore developed a floating mini-factory on a boat about thirty meters long, which pumps seawater and subjects it to an electrical charge.
Electrolysis then triggers a series of chemical reactions that end up neutralizing the CO2 initially contained in the water. This gas is trapped in a fine white powder that contains calcium carbonate and magnesium bicarbonate.
These natural minerals can be released into the ocean, allowing “store CO2 in a very sustainable way (…) for tens of thousands of years“, according to Gaurav Sant. And the pumped water returns to the sea, ready to reabsorb the greenhouse gas from the air.
The director of the Institute of Carbon Management is confident that the process will have no impact on the marine environment, but this has yet to be confirmed. In addition to removing CO2 from the atmosphere, the process also produces hydrogen, a gas essential to the energy transition.
The priority for curbing climate change remains to drastically reduce our C02 emissions, which humanity is currently unable to do, assured the scientists.
However, most scientists point out that CO2 capture and storage techniques, collectively referred to as “carbon dioxide removal“(CDR), will play a complementary role in keeping the planet livable.
Initially, these techniques will make it possible to achieve carbon neutrality by 2050 by offsetting the emissions of the most difficult industries to decarbonise, such as aviation, cement or steel. Subsequently, they will be able to tackle to the stocks of CO2 accumulated in the atmosphere for decades.
To be able to keep global warming under control this requires extracting between 450 billion and 1.1 trillion tonnes of C02 from the atmosphere by 2100. This implies that the CDR sector “grow at a rate of around 30% per year over the next 30 years, much like solar and wind have done“, insisted one of the authors of a report published on the subject, Gregory Nemet, professor at the University of Wisconsin-Madison.
UCLA technology”falls into the category of promising solutions that could be large enough to have an impact on the climate“, according to the latter. The scientist explained that by sequestering CO2 directly in the ocean in mineral form, it differs markedly from the direct capture of CO2 from the air (DAC).
This technique requires finding a site to store the gas in the ground, a very complex and expensive process. “A big advantage of our process is that we don’t need to pump CO2 into the ground“, continues Gaurav Sant.
The project will be marketed by a start-up, Equatic, responsible for demonstrating its feasibility on an industrial scale and selling carbon credits to companies wishing to offset their emissions.
Besides the Los Angeles barge, a similar boat is currently being tested in Singapore. The results of the experiments at the two sites should make it possible to design larger-capacity plants, capable of “sequester thousands of tons of CO2 per year“, according to Gaurav Sant, who hopes that they will be operational within “18 to 24 months”.
