In what could be a major breakthrough for dealing with the planet’s climate change problem, a team of scientists captured a greenhouse gas and chemically changed it into a solid, and they did it far more quickly and efficiently than experts anticipated.
Working alongside engineers at the Hellisheidi power plant in Iceland, earth scientists from the US, UK, and elsewhere demonstrated the ability to convert carbon dioxide emissions into stone by pumping them into the Earth, mineralizing the majority of it in less than 24 months.
Their work could help alleviate concerns that captured CO2 being stored underground might be able to seep back out into the atmosphere, or at the very worst, explode. The technique they used is detailed in research published in the Friday, June 10 edition of the journal Science.
“We can pump down large amounts of CO2 and store it in a very safe way over a very short period of time,” study coauthor Martin Stute, a hydrologist at Columbia University’s Lamont-Doherty Earth Observatory, said in a statement. “In the future, we could think of using this for power plants in places where there’s a lot of basalt – and there are many such places.”
The rush of carbon dioxide allowed a green slime mold to grow that potentially played a part in the reaction. Credit: Columbia University
So how does this process work?
According to the study authors, the Hellisheidi power plant is the largest geothermal facility on Earth, and provides power for nearby areas by pumping up volcanically-heated water in order to operate turbines. Ordinarily, this process also gives off carbon dioxide and other volcanic gases, but new pilot project launched four years ago is looking to address that problem.
This project is known as Carbfix, and it involves mixing those gases with water pumped up from below, then injecting that solution back into the volcanic basalt. The result is a chemical reaction in which the carbon precipitates out into a chalky, white mineral. Previous research has estimated that this process could take hundreds of years or more. At the Hellisheidi plant, however, Stute’s team was able to solidify 95 percent of the carbon in only two years.
Basalt is the key to this reaction. Credit: University of Columbia
Since nearly all of the seafloors on the planet and 10 percent of continental rocks are made of basalt, there is no shortage of places where this carbon capture and solidification procedure can be used, the researchers explained. They also reported that the carbonate minerals they created have been stable, meaning that there should be little risk of carbon leakage with the technique.
Since 2014, Reyjavik Energy, the company that operates the plant, has been injecting CO2 at the rate of 5,000 tons per year while keeping pace with the mineralization efforts, and engineers said that there are plans to double the injection rate this summer. While other power plants are said to have expressed interest in the technology, the authors note that there are some obstacles, such as the amount of water needed (approximately 25 tons per ton of CO2), and the cost (in most plants, the separation and injection process would cost about $130 per ton, though it is considerably less at the Hellisheidi facility, since it uses existing infrastructure and does not purify the carbon).
In addition, earlier this year, researchers identified a type of subterranean microbe that seem to feed off carbonate minerals, releasing a more potent greenhouse gas, methane, in the process, so that could be a problem the engineers need to address. Even with the roadblocks, however, lead author Juerg Matter from the University of Southampton is confident he and his colleagues have found a new weapon in the fight against global warming. “We need to deal with rising carbon emissions,” he said. “This is the ultimate permanent storage – turn them back to stone.”
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Image credit: Kevin Krajick/Lamont-Doherty Earth Observatory
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