Turning Carbon Dioxide to Stone – ‘CarbFix’

Carbon dioxide – our friend and our foe.

According to NASA, the current level of carbon dioxide in the Earth’s atmosphere is the highest it has ever been in the past 400,000 years [1].

The general consensus amongst climate scientists is that we, as a human race, need to reduce our carbon dioxide emissions for the good of the planet, its ecosystems and their inhabitants. This year scientists working in Iceland have released a paper claiming they have discovered a new way to trap this greenhouse gas, by changing it into rock and storing it deep underground [2]. Dr Matter and his team have dubbed it ‘CarbFix’.

How was ‘CarbFix’ discovered?

By accident! As many great things have been discovered, the science behind ‘CarbFix’ was stumbled upon by chance. The Hellisheidi geothermal power plant in Reykjavik, Iceland, releases around 40,000 pounds of CO2 per year [7] and the scientists working there were trying to further fight climate change by reducing those emissions by injecting them back into the ground that they came from in order to achieve carbonation. After just a year and a half a few pumps kept breaking down and they noticed a white calcium rich build up on the ends of the pumps. After investigation they realised that this material was a product of a reaction occurring between the CO2, water and basalt rock. They had seemingly managed to turn carbon dioxide into rock in just under two years, a feat thought impossible [6].

How does ‘CarbFix’ Work?

No, it doesn’t involve the entire population skipping carbs for three days a week…

When carbon dioxide and water are together exposed to basalt (a rock crucially containing metal), a chemical reaction occurs [3] which converts the gas into carbonate materials such as calcite and magnesite [4]. These are stable minerals and therefore provide a safe ‘cage’ within which the carbon dioxide can be locked away indefinitely [4]. The dissolution of silicate minerals by carbon dioxide-rich fluids and the consequent conversion of CO2 into carbonate minerals as a way of permanently storing anthropogenic CO2 waste has been understood for a few years, however, uncertainty hung over how long this process would take due to lack of understanding over the rates of mineral dissolution [5]. Earlier studies suggested that the process could take thousands of years for substantial amounts of carbon to be stored this way [3]. In Iceland, ‘CarbFix’ took them just two years [3].

What are the pros and cons?
Cons:

• Not 100% of the carbon dioxide is stored. There is still a small leakage of about 5% [6]
• 25 tons of water are required for every ton of CO2 converted [6]
• Injections costs around $130 per ton of CO2 [6]
• Due to a lack of a price on carbon emissions, power companies have little incentive to invest [2].

Pros:

• Seawater could also be used in the reaction, potentially reducing the costs [6]
• Great way for fossil fuel-based power plants to reduce their carbon emissions [6]
• Basalt is found worldwide so this method has a global potential [7]

In conclusion, ‘CarbFix’ is a project with the potential to reduce our global carbon emissions in a safe and permanent manner. Its most pressing obstacle is the lack of a business case it presents to power companies, and persuading them to pursue this is going to be a tough challenge. Many would argue that the bulk of our fight against climate change should focus on reduction of emissions, however Carbfix could prove a strong component in the portfolio of solutions so let’s hope ‘CarbFix’ takes off, the fight against climate change needs some positive input!

Bibliography

1. The relentless rise of carbon dioxide (2016) Available at: http://climate.nasa.gov/climate_resources/24/ (Accessed: 1 August 2016).
2. Kintisch, E. (2016) Underground injections turn carbon dioxide to stone. Available at: http://www.sciencemag.org/news/2016/06/underground-injections-turn-carbon-dioxide-stone (Accessed: 1 August 2016)
3. Magill, B. (2016) Scientists turn carbon dioxide emissions to stone. Available at: http://www.climatecentral.org/news/scientists-turn-carbon-dioxide-emissions-to-stone-20425 (Accessed: 1 August 2016).
4. Economist, T. (2016) Turning air into stone. Available at: http://www.economist.com/news/science-and-technology/21700371-how-keep-waste-carbon-dioxide-ground-turning-air-stone (Accessed: 1 August 2016).
5. Maskell, A., Kampman, N., Chapman, H., Condon, D.J. and Bickle, M. (2015) ‘Kinetics of CO–fluid–rock reactions in a basalt aquifer, soda springs, Idaho’, Applied Geochemistry, 61, pp. 272–283. doi: 10.1016/j.apgeochem.2015.06.010
6. Phys (no date) In a first, Iceland power plant turns carbon emissions to stone. Available at: http://phys.org/news/2016-06-climate-mitigation-co2.html (Accessed: 1 August 2016).
7. Institute, E. (2016) Turning carbon emissions to stone. Available at: https://vimeo.com/119512256 (Accessed: 1 August 2016).