To combat climate change, these scientists are turning CO2 into rock

Carbon dioxide in the atmosphere is a major contributor to global warming. But what if there were a way to turn that gas into rock and store it safely, thousands of feet underground? One power plant in Iceland is attempting to do just that, through a process called “Carbfix.” Special correspondent Malcolm Brabant reports, in the first of his “Breakthrough” series.

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    Reducing the amount of carbon dioxide in the atmosphere is a key to slowing climate change. Scientists based in Iceland have made a major breakthrough by transforming carbon dioxide, or CO2, into rock.

    And the head of the research group says it's possible that 40 percent of the world's carbon dioxide emissions could be dealt with by adopting their techniques.

    Special correspondent Malcolm Brabant has been to Iceland to examine this promising discovery, and he reports now as part of our Breakthrough series.


    I'm standing about 1,000 feet up a volcano that last erupted about 2,000 years ago. The temperature underground here is about 620 degrees Fahrenheit. According to geologists, this volcano could blow at any time. But that could be any time within the next 1,000 years.

    The process of turning carbon dioxide into rock is happening about 6,000 feet below my feet silently. But up here, you can really sense the visceral power of Mother Nature. The only sensation I can compare it to is being rather close to the launch of a space shuttle.

  • WOMAN:

    This is Hellisheidi geothermal power plant. The thermal energy is transported towards Reykjavik, where we heat our houses and take showers and so forth.

  • EDDA ARADOTTIR, CarbFix Project Director:

    So, as a byproduct of the ongoing energy production, geothermal gases like CO2 are emitted to the atmosphere. But we have been working towards reducing these emissions, capturing them and reinjecting them into the ground and turning them into rock.


    The techniques pioneered here are said to be safer than the alternative of storing CO2 as a gas underground, with its expense and potential for leaks.

    Under the right conditions, nature takes hundreds of years to transform CO2 into stone. What the scientists have done is to accelerate the process exponentially.


    This represents methods that can be used for fighting global warming and climate change. And to that respect, it's a powerful box.

    So, this is calcium carbonate. And this is what the CO2 injected into the basalt turns into after the chemical reactions have occurred. This one is not representative of what we would see if we were to drill a core or dig a hole into the bedrock where we are injecting the CO2. Rather, we would see something like this, where we have the calcium carbonate in smaller particles.


    Carbon dioxide is an invisible gas. But it is ever-present in geothermal areas like this one, where there are hot springs and mud pools.

    Iceland's volcanic rock makes it the perfect test bed for CarbFix. Geologist Bergur Sigfusson drove up the volcano to point out the key ingredient for this chemical reaction: basalt.

  • BERGUR SIGFUSSON, Geologist:

    Here we are standing in a basaltic lava field. These rocks here are essentially the same as we are injecting our CO2 into, approximately 5,000 feet below sea level. The basalt contains all the necessary elements we need to combine with the CO2 to form minerals in the subsurface.


    Professor Siggi Gislason is the head of the scientific team running this experiment. Among the participating institutions, Columbia University in New York.

    As he explains, the key toy ensuring there are no gas leakages is to dissolve the CO2 in water before injecting it into the bedrock.


    We simulate the injection by having here pure water, pure water that goes in here. And then we have the CO2 that we put in the stream.

    It's something similar to what we have at the CarbFix site, where we have CO2-charged water that enters the basaltic rocks at depth. What we have done so far is a small project, but it's beautiful, because we have shown that you can actually mineralize CO2 within two years in reactive rocks like basalts.

    And that's the safest way of storing carbon in the earth.


    Here, engineers are drilling to extract samples from the carbon dioxide-infused rock. This method requires huge amounts of water to dissolve the CO2, so it can be penetrate the porous and permeable basalt. Twenty-five tons of water is needed for every ton of carbon dioxide.

    At present, the CarbFix project is neutralizing 10,000 tons of CO2 a year.

    Project director Edda Aradottir:


    We're looking at a core that was drilled into the CarbFix injection site. And we see when we look at it that, inside the basalt, we have carbonate minerals already formed containing the injected CO2.


    Hildigunnur Thorsteinsson is the head of research and development at Reykjavik Energy.

    How significant is what you are doing here?


    I think the CarbFix project is one part of the solution. I think the problem with climate change and what makes it so difficult is that there is no silver bullet. And so the CarbFix project isn't a silver bullet, but it's certainly, certainly another weapon in our armory.


    So, how much of the world's carbon could you get rid of if you employed this around the world?


    I don't have the exact numbers, but we do have significant potential in the ocean ridges, in countries like India that could really use this technology.


    Only a few places on land, like Northern California and Southern Oregon, have the right kind of geological composition to make this work.

    But since basalt is plentiful on the ocean floor, burying CO2 Offshore just might work for other countries trying to contain the greenhouse gas.

    To the west of Iceland and slightly closer to the North Pole is the Jakobshavn Glacier in Western Greenland, which is a barometer of climate change. During the 20th century, it alone was responsible for 4 percent of rising ocean waters. Due to warmer sea temperatures, the glacier is shrinking at the rate of 10 miles a year, and spawning a greater number of icebergs of the size that sank the Titanic.

    Professor Rene Forsberg is a climate specialist at Denmark's Technical University.

    RENE FORSBERG, Technical University of Denmark: It's a sign of global warming that Greenland is melting rapidly, the ice sheet is melting rapidly, producing more icebergs. And we know that it's warmer in Greenland now on average than it's been for many years. So this is what we see here, that the icebergs get more frequent. They get larger also to some degree.


    Because it is self-contained within the geothermal power plant, the CarbFix solution cannot be used for capturing CO2 from planes, cars and ships like this one in a Norwegian fjord.

    But Professor Gislason believes there should be international law requiring countries to start using this new technique.


    The more diffuse emissions like from jets, cars, et cetera, is going to be more complicated, but still 40 percent of the emissions could theoretically be captured and stored in rocks.

    There is no question we need legislation to force people to do this. But do you want to do this by an emission trading scheme? Do you want to do it by carbon taxes? Or do you want to do it strictly, directly by legislation. If you do this, then you capture the CO2. It has to be done because it is expensive. And that is the Achilles' heel of all of the carbon capture and storage. It is expensive.


    But even here in Iceland, it's not being used to its full extent.


    Seventy-five percent of the CO2 is emitted at the moment. Of the CO we take up to the surface, approximately 25 percent are reinjected directly to form the carbonates, minerals.


    Why are you only injecting 25 percent of the carbon dioxide that you are produce into the ground? Why aren't you going full out and putting in 100 percent?


    CO2 emissions from geothermal energy are not very large. And so we — but we saw an opportunity here to test a very interesting technology, which we did. And we even proved it works faster than we thought it would.

    Now, as for future development, we haven't decided on that. So we might expand at a later point, but we just haven't made that decision.


    But if you're trying to save the planet, why don't you put in 100 percent?


    Well, when we were testing the technology, we didn't know if it would work. And so we only started injecting two years ago. We're still proving that we can keep it all down there, everything turns to minerals.

    As the future progresses, we might do more. We haven't decided.


    The scientists aren't resting on their laurels. They're trying to determine whether they can speed up the process still further.

    For the "PBS NewsHour," I'm Malcolm Brabant in Iceland.

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