Salt is one of the oldest and most famous preservatives. But could it be used to store carbon deep underground for thousands of years? I believe that it may provide a way forward.
As emissions of greenhouse gases such as carbon dioxide continue to rise and the climate feedback loops driven in part by these emissions accelerate, finding ways to suck carbon dioxide out of the air has been challenging. has become even more important. The problem is that the fast and efficient DAC (Direct Air Capture) technology developed last year by researchers at Tokyo Metropolitan University can be quite expensive to build and maintain.
For example, the world’s largest carbon capture plant, set to open in Wyoming this year, will cost US$600 to capture one tonne of carbon from the atmosphere, but the project’s developers will ultimately reduce the cost to $100. range. Even at $100 per tonne, the cost would be enormous given that nearly a billion tons of carbon would need to be removed from the atmosphere annually to meet current climate goals.
Scientists are therefore scrambling to find other ways to get carbon dioxide out of the atmosphere in a more cost-effective manner. Earlier this year, MIT scientists proposed a relatively cheap way to remove carbon from the world’s oceans so it could absorb more from the atmosphere, and last year, chemists at the University of California, Berkeley, They proposed using a cheap material called melamine to absorb the carbon. Carbon from chimneys and exhaust pipes.
Another affordable method of capturing carbon from the air is known as agricultural sequestration. It might sound like something a grumpy tween would do on a bad day, but in reality, this technique involves growing carbon-sequestering crops (such as certain grasses) and then placing those crops in the ground. It involves burying deep within the The problem is that when bacteria start decomposing these crops, the carbon is released back into the atmosphere.
To overcome this hurdle, Berkeley scientists have come up with a simple solution: salt. First the crops are dried and the biomass lined with a 2 mm thick polyethylene layerhe is buried in a pit, then salt is added so that the crops can store carbon underground for centuries.
“For many of these recently popular nature- and agriculture-based technologies, there are important questions regarding long-term isolation,” said Harry Deckman, co-author of a new study on the method. “Our proposed agricultural sequestration approach can stably sequester carbon in dry and salted biomass for thousands of years at a lower cost and higher carbon efficiency than these other air capture technologies. increase.”
Unlike DAC technology, the solution costs as little as $60 per tonne of carbon dioxide captured and sequestered, researchers say. Additionally, 2 tonnes of carbon dioxide can be sequestered per tonne of dry biomass, making the process carbon negative.
The team compiled a list of highly productive plants, most of which can be grown on marginal land not currently used to grow crops. They also say that one hectare pit can hold material from 10,000 hectares of biomass. Using these calculations, the researchers say it would require only one-fifteenth of the world’s farmland, forests, and pastures to sequester half of the world’s greenhouse gas emissions. .
“It takes a lot of farmland to remove all the carbon produced, but it’s the amount of farmland that’s actually available,” Yablonovitch said. “This will be a huge boon for farmers as there is currently underutilized farmland.”
The study was published in the journal PNAS.
Source: University of California, Berkeley
