The Great Carbon Valley is something you’ve probably never heard of. I certainly hadn’t. The article I read, with that as a title, revealed that the author was talking about the Great Rift Valley in East Africa. It immediately attracted my attention, having spent some time in East Africa, and remembering one of my favorite books, The Lunatic Express, which is the story of how they built the railway from Mombasa to Kampala through the Great Rift Valley.
The article I read reported on a Kenyan environmental and development expert, James Irungu Mwangi, who believes that the Great Rift Valley would be an ideal, and possibly unique, place to help solve the earth’s carbon dioxide problem. The Rift Valley could not only house and power the plants that could suck carbon dioxide out of the air, it could also serve as a storage facility to permanently trap the recovered gas. In other words, he suggests we create the Great Carbon Valley.
The Great Rift Valley was created by the separation of two tectonic plates, which makes the earth’s crust in the bottom of the valley significantly thinner than normal on earth. That means that access to the earth’s geothermal energy is much simpler, and therefore cheaper.
One of the problems with the processes that capture carbon dioxide from the atmosphere (DAC – Direct Air Capture) is that they use a great deal of energy. Access to cheap energy is therefore essential. Energy is needed to power the fans that blow air over the chemicals that absorb carbon dioxide, and more energy is needed to extract the gas from those chemicals so it can be compressed and stored. Estimates of the power Kenya could produce from geothermal sources are as high as 10,000MW, which is four-times the amount the country now produces. AND it’s renewable, and doesn’t pollute. In fact, 90% of Kenya’s power is renewable.
The Great Rift Valley floor also has a geology that is compatible with carbon dioxide storage. It has thousands of square kilometers of porous basalt rock. The carbon dioxide recovered from the atmosphere would be dissolved in water (the same process that produces sparkling water), and that water would be pumped into the porous rock where it would react to form carbon-rich minerals. Once formed these carbon-rich minerals effectively trap the gas, and it cannot then leak back into the atmosphere.
The gas removal technology is not new. A Swiss company, Climeworks, has built a DAC plant in Iceland. However, those removal costs are $600-800 per ton. Octavia, a start-up company in Kenya’s Rift Valley, anticipates that it can do the same for around $100 or less per ton, which is even far below the current industry estimates of $300-400 per ton.
The Great Rift Valley is one of the most spectacular sites in the world. It is surrounded by volcanos, lakes full of flamingos and teeming with the wildlife for which African safaris are famous. If it could also become a non-polluting storage facility for one of the worst greenhouse gases, it reputation can only soar. The names of Great Rift Valley and Great Carbon Valley could become synonymous.
The East African Rift Valley is not the only continental rift valley created by the movement of tectonic plates. There is one in Siberia – the Baikal Rift Valley – one in Antarctica – the West Antarctica Rift Valley, and the Rio Grande Rift Valley on the U.S./Mexican Border. There are several more under the sea – the Mid-Atlantic Ridge is a large one, which only appears above the surface in Iceland – hence the Climeworks project. The West Antarctic Rift Valley has an access issue in that it is under two kilometers of ice. That leaves two others that are continental, and therefore relatively accessible and, thus, possibly available for carbon dioxide capture and storage.
Overall, the concept of a Great Carbon Valley could provide a significant solution to the world’s atmospheric carbon dioxide problem in a non-polluting and secure way.
As a caveat, which I recently discovered, the northern end of the Great Rift Valley is expanding rapidly – it has expanded 400 years-worth of normal expansion in a couple of years. Experts say it could eventually split the continent of Africa in two, with a sea in the middle. However, that is unlikely to affect carbon dioxide storage since the timeframe for such a divided Africa is about a million years!
