Scientists find a way to soak up carbon pollution, turn it into baking soda and store it in the ocean
(CNN) Scientists have devised a way to suck up planet-warming carbon pollution from the air, turn it into sodium bicarbonate and store it in oceans, according to a new paper.
The technique could be up to three times more efficient than current carbon capture technology, say the authors of the study, published Wednesday in the journal Science Advances.
Tackling the climate crisis means drastically reducing the burning of fossil fuels, which release pollution from the planet. But because humans have already pumped so much of this pollution into the atmosphere and are unlikely to reduce emissions sufficiently in the short term, scientists say we need to remove it from the air, too.
Nature does this – forests and oceans, for example, are valuable carbon sinks – but not quickly enough to keep up with the amounts humans are producing. So we’ve turned to technology.
One method is to capture carbon pollution directly at the source, for example from steel or cement works.
But another way, which this study focuses on, is “direct aerial capture”. This involves sucking carbon pollution directly out of the atmosphere and then storing it, often by injecting it into the ground.
The problem with direct air capture is that while carbon dioxide can be a very potent planet-warming gas, its concentrations are very small – it makes up about 0.04% of the air. This means that it is challenging and expensive to remove it directly from the air.
That’s a “significant hurdle,” Arup SenGupta, a professor at Lehigh University and a study author, told CNN.
Even the largest plants can only remove relatively small amounts and it costs several hundred dollars to remove each tonne of carbon.
Climeworks’ direct air removal project in Iceland is the largest facility, according to the company, and can capture up to 4,000 tonnes of carbon dioxide a year. That is equivalent to the carbon pollution produced by fewer than 800 cars in the course of a year.
The new technique laid out in the study may help tackle these problems, SenGupta said.
The team has used copper to modify the absorbent material used in direct air capture. The result is an absorbent “that can remove CO2 from the atmosphere at ultra-dilute concentration with a capacity two to three times greater than existing absorbents,” SenGupta said.
This material can be produced easily and cheaply and will help reduce the cost of direct air capture, he added.
Once the carbon dioxide is trapped, it can be converted into sodium bicarbonate – baking soda – with the help of seawater and released into the sea in a small concentration.
The oceans “are infinite things,” SenGupta said. “If you put all the CO2 from the atmosphere, which is released every day – or every year – into the ocean, the increase in concentration will be very, very small,” he said.
SenGupta’s idea is that direct air capture facilities can be located offshore, giving them access to abundant seawater for the process.
Stuart Haszeldine, professor of carbon capture and storage at the University of Edinburgh, who was not involved in the study, told CNN that the chemistry was “new and elegant.”
The process is a modification of one we already know, he said, “which is easier to understand, scale up and develop than something entirely new.”
But there may be regulatory hurdles to overcome. – Disposing of large tonnages of sodium bicarbonate in the sea can legally be defined as “dumping”, which is prohibited in international treaties, said Haszeldine.
Others are still concerned about negative consequences for the oceans, which are already under pressure from climate change, pollution and other human activity.
Peter Styring, professor of chemical engineering and chemistry at the University of Sheffield, told CNN: “Unless you have a full ecotoxicity study, you don’t know what it’s going to do, even at small concentrations.”
Direct aerial capture also remains expensive and ineffective, Styring said. “This is a problem on a large scale. Why would you capture from the atmosphere when you have so much coming out of power stations and industrial plants? It just makes sense to go for the high concentrations first,” he said.
Some scientists have expressed concern that a focus on technology to remove carbon pollution could distract from policies to reduce fossil fuel burning, or could give polluters a license to continue polluting.
But given the scale of the climate crisis, there is great pressure from authorities and international bodies to scale up this technology.
More research will be needed to understand how the method works at scale, Haszeldine said. But it’s promising, he added, saying “the world needs a lot of these kinds of discoveries.”
SenGupta said the technology is ready to be taken out of the lab and tested. “This is the time to go ahead and do something in maybe two or three different places around the world. Let other people get involved, find mistakes, improve it, and then continue accordingly,” he said.