Turning carbon dioxide into rock forever

G Svanberg

Nested in the snow-covered mountains to the west of Iceland, a maze of turbines and pipes belches up thick billows of steam. This gigantic structure is responsible for the supply of electricity in a country where 100% of the electricity comes from renewable sources.

The Hellisheidi power station, 25 km (15 miles) outside of Reykjavik, Iceland’s main geothermal plant, and is one of the largest in the world.

“Do you feel the vibrations beneath us?”, says Edda Sif Aradottir, the director of the center, the splashing of snow, as she treads on her shoes on the floor. “It is the steam coming into the turbine”.

A Saeberg

“It is a volcanic region. We harness the volcano’s internal heat to produce electricity and hot water for the city’s heating system, our swimming pools and showers. We Icelanders like our showers are really hot!”

Hellisheidi is not only made of a green energy provider. It is also the site for a scientific breakthrough; an experiment to capture the carbon dioxide (CO2) and convert it into stone for eternity.

Therefore, to keep this greenhouse gas from the atmosphere and put a dent in the warming of the planet.

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We have already reached the tipping point for CO2 levels in the atmosphere and extreme events that will occur if we do not act quickly and implement all the solutions available” ____________

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“Humanity has been burning fossil fuels since the industrial revolution, and we have already reached the tipping point for CO2 levels,” explains Dr. Aradottir. “This is one of the solutions that can be applied to the reverse that”.

Called CarbFix, the project was launched by an international consortium led by Reykjavík Energy, the National Center of Scientific Research, the University of Iceland and Columbia University.

Since the experiments have started in 2014, it was scaled up from a pilot project to a permanent solution, cleaning up to one-third of the plant’s carbon emissions.

“More importantly, we are a testing ground for a method that can be applied elsewhere, a power plant, heavy industries or any other CO2 emitting source,” explains Dr. Aradottir.Making soda

With the increasing concentrations of CO2 in the atmosphere, scientists have tested carbon capture and storage” (CCS) solutions since the 1970s.

CarbFix, however, differs among CCS experiences because the carbon capture is said to be stable and fast.

The process begins with the capture of waste CO2 from the steam, which is then dissolved in large volumes of water.

“We use a giant soda machine,” explains Dr. Aradottir as she points to the separation of gas station, an industrial building that stands behind the roar of the turbines.

“Essentially, what happens here is similar to the process in your kitchen when you make it yourself sparkling water: we add fizz to the water”.

The bubbly liquid is then piped to the injection site – another world, geometric igloo-shaped structure to 2 km. There it is pumped to 1 000 m (3 200 ft) below the surface.

In a few months, a chemical reactions to solidify the CO2 in the rock – thus preventing it from escaping into the atmosphere for millions of years.

In what seems to be the magic of the feat, the local geology plays an essential role.Porous rock

The breathtaking Icelandic landscape – with its hot springs, geysers and black beaches – is mainly made of basalt, a dark gray porous rock formed by the cooling of the lava.

And the basalt is “carbon” best friend”, because it contains large amounts of calcium, magnesium and iron, which bind with the pumped CO2 to help it solidify into a mineral.

S Gislason

S Gislason

Sandra Snaebjornsdottir, a geologist working for CarbFix, has the proof in his hands: a sample cylindrical drilled from the website shows a handful of crystals of limestone embedded in the basalt.

“These white bits are the carbonates, or the mineralization of the CO2,” she said. “Fresh basalts are like sponges, with lots of cavities that are filled with CO2.

“Iceland is a particularly favorable for this type of CCS, simply because of the amount of basalt, it is obtained”.

Last year, 10 000 tons of CO2 have been “digested” by CarbFix.

Yet, it’s a tiny fraction less than the annual emissions of 650 British or 2,200 American cars.

And it becomes even more negligible on the 30 to 40 gigatonnes of CO2 (in gigatons is a billion tons) that modern humans pour into the atmosphere each year.

Despite its relatively small scale, the experts anticipate CarbFix could be easy to repeat – thanks to the ubiquity of basalt throughout the world.

“The basalt is in fact the most common type of rock on Earth, it covers most of the seabed and approximately 10% of all the continents. Everywhere where there is basalt and water, this model could work,” said Sandra Snaebjornsdottir.

Large areas of basalt are found in Siberia, in the West of India, Saudi Arabia, and the Pacific north-west.

And scientists are now trying to test the model on the oceans in order to take advantage of the extent of areas of sub-marine basalt formations.

Potentially, the basalt could solve all the world’s CO2 problems, ” explains Sandra: “The storage capacity is such that, in theory, the basalts could permanently hold all of the bulk of the CO2 emissions from the combustion of all fossil fuels on Earth.”Very thirsty

At the University of Iceland, research around CarbFix has been continuous since its pilot phase.

A desk-size replica of the pipes and pumps in Hellisheidi in a state-of-the-art lab allows Prof Sigurdur Gislason to review the process.

“Before the injection began in CarbFix, the consensus within the scientific community is that it would take decades for thousands of years for the injected CO2 to mineralise,” said Prof Gislason explains.

“Then we discovered that it was already mineralized after 400 days.”

The reactions were much faster than expected, in part because of the large amount of water used to dissolve the CO2.

This however points to one of the Achilles heels – it is very water intensive.

“He needs more than 25 tonnes of water per tonne of CO2,” said Prof Gislason. “In Iceland, we are blessed with lots of rain, but if you do it on the basalt areas in India… their water is very valuable”.

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The bottleneck is now the law, we will not solve climate change unless CO2 emitters are required to pay a price in the range of 20 to 70 euros per ton of CO2 emitted” ___________

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Some critics warn high-tech bugs like this one poses a greater risk as to distract the researchers, and the public of the urgent need to drastically reduce greenhouse gas levels.

In a recent report, the European Academies Science Advisory Council warned that such technologies have “limited realistic potential” if emissions are not reduced.

“CarbFix is not a panacea. We have to reduce emissions and develop renewable energy sources, and we have to make CCS too,” said Prof Gislason.

We need to change the way we live, which proved to be very difficult for people to understand.”

A part of our series Taking the Temperature, which puts the emphasis on the fight against climate change and the people and ideas to make a difference.

This BBC series has been produced thanks to the support of the Skoll Foundation

Illustrations by Jilla Dastmalchi