“Storing CO2 as carbonate minerals significantly enhances storage security which should improve public acceptance of Carbon Capture and Storage as a climate change mitigation technology”, Matter added.
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The results, published on Thursday in the journal Science, are hoped to offer new hope for an effective weapon to help fight man-made global warming. The experimental project has been successful in converting 95 percent of carbon dioxide to limestone. “People knew it would work but didn’t know the timescale – whether it would be rapid enough to be useful”. Both of them joined hands and the project was kick-started.
One of the attendees was the president of Iceland.
After a successful pilot in 2012, the plant has continued injecting carbon dioxide underground, and ongoing monitoring suggests the mineralisation process is keeping on consistently and safely – which could calm fears that storing CO2 underground might be unsafe. The two got to talking, and the project was born.
The Hellisheidi power plant is the world’s largest geothermal facility; it and a companion plant provide the energy for Iceland’s capital, Reykjavik, plus power for industry, by pumping up volcanically heated water to run turbines.
Partnering with a geothermal energy plant means the deep boreholes, which are expensive to drill, are already in place. The plant emits 40,000 tons of Carbon dioxide annually. And even this is at the high end for geothermal plants, many of which produce no emissions.
Researchers conducted their experiments in Iceland, where the bedrock is some 90 percent basaltic – a product of the island’s volcanic past – and rich in calcium, magnesium and iron. Scientists dissolved Carbon dioxide in water and pumped it deep into the bottom of a well. Coffee grounds and sea urchins have inspired some of the more imaginative approaches, but largely the focus remains on pumping it into rock formations that react with the gas and turn it into solid carbonate minerals. After two years, the mix had turned into stone. The company plans to double that rate this summer. Their eventual goal is to capture and sequester all their emissions in the same way. “They’ve actually upscaled this and are using it”.
We asked Jason Veysey, a senior scientist with the Stockholm Environment Institute who was not involved with this research. “It represents the tip of the iceberg”.
Experiments made until now with carbon sequestration weren’t too promising. As fossil fuels are burnt, the carbon stored in them releases during the process.
One solution could be the use of seawater, though salt water’s efficacy remains untested, says Columbia’s Dr. Stute. There are restrictions with the projects like the availability of basalt. And because this technique relies mostly on water and porous basaltic rocks, both of which are widely available on continental margins in many parts of the world, scaling up will be feasible, the authors say.
The technique could lead to reduction of greenhouse gas emissions from power plants.
The final hurdle is cost.
“It’s no longer a gas”, Dr Matter said. It’s one of the most common types of rock on Earth, and it naturally mineralizes carbon into its own rocky structure, where it remains stable for millions of years. First of all, carbon separation and injection tends to cost about $130 per ton, while this method costs barely $30 per ton.
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However, there are still several key issues that need to be worked on before the technology can be scaled up.
