If you have frugal jewlery tastes or a birthday in August, you are probably already familiar with Peridotite – the crystals of which, once cleaned and polished, are called Olivine or, if gem-quality, Peridot. It’s known for its brilliant green color and inexpensive price. However, the rock is more than just green in color – it acts ‘green’, too. That is, it naturally reacts with carbon dioxide to form carbonates, removing the gas from the atmosphere. Unfortunately, the rate at which it does so naturally is slow, so currently the rocks make little impact on a global scale.
Enter researchers at Columbia University. The theory is to use the rocks, found in Oman, California, New Guinea and elsewhere to trap the carbon permanently to slow or stop global climate change. People had thought about this before, but deemed it too expensive to transport the rocks to industrial areas. Well, yeah, say the Columbia researchers – but we can transport the CO2 to the rocks. Their new study, available online from PNAS, details a new method of carbon sequestering.
In the Omani desert, peridotite is already naturally absorbing 10,000 to 100,000 tons of CO2 each year. Columbia’s scientists believe that they can speed up the carbon-locking process by 100,000 times by boring holes into the ground and injecting heated CO2-rich water. The key is increasing the contacting surface area and the heat – both speed up the process dramatically. What’s more, because the reactions themselves generate heat, once they reach a certain rate, they could become self-sustaining, which would reduce the costs. Small scale tests have been successful – now they need to do big ones.
To the left is their example of a set-up that could use the sea floor to sequester carbon from ocean water. In general, this method is particularly appealing because today’s strategy for carbon sequestration involves pumping it underground, where it’s trapped in porous aquifers (water). This gives the CO2 a chance to leak out due to earthquakes or other natural events, releasing massive amounts of buried CO2 into the atmosphere. So a permanent solution would be a vast improvement. Also, there’s a lot of peridotite out there – peridotite is the dominant rock of the upper part of the Earth’s mantle – so there’s a lot of potential area to utilize this new technology.
