Mountains in Oman Can Store Huge Amounts of CO2 if a Way Can Be Found Into the Tight Rock

Abstract

Every year, the unusual mix of minerals in the Hajar Mountains near the coast of Oman traps 100,000 tons of carbon in the rock. That estimate is a tiny fraction of the potential of the mountain range and a few others like it in the world. Based on decades of work by geologists studying this unique formation—known as the Samail Ophiolite—the highly reactive rocks called peridotites can theoretically trap one-half ton of CO2 per ton of that rock in the Hajar Mountains, which extend into the UAE. A leading voice among the researchers who made the 100,000-ton estimate and developed ideas for removing trillions of tons of carbon from the atmosphere is Peter Kelemen, a professor at Columbia University in New York City. In a 2019 story in Scientific American, Kelemen said that if it is possible to speed the pace of mineralization “by a factor of a million”—something he thinks is doable with a bit of engineering—“then you end up with a billion tons of CO2 per cubic kilometer of rock per year.” That potential inspired an Omani entrepreneur, Talal Hasan, to start a company based on the work of Kelemen and colleagues including Juerg Matter, a geochemist now working at the University of Southampton in England. The result was startup 44.01, named for the molecular mass of carbon, where Kelemen serves as an advisor and Matter works part time. The company’s website describes its plan: “Carbon mineralization in peridotite is happening all the time—we simply speed up the natural process.” It is a simple-sounding goal. But what it will take to realize the vast potential is anything but simple. In an interview, Kelemen identified why: “The main concern is that the rocks are not very porous.” Or very permeable, which helps explain why large amounts of highly reactive elements have remained untouched over the 96 million years these reactive minerals have been on land. The hard rocks in this formation, particularly magnesium-rich olivine, were produced when magma flowed up from the mantle to a mid-ocean ridge where it cooled and the thick layer of rock spread out toward what is now Oman and the UAE, and something extraordinary happened. When it reached the boundary between two plates, it normally would have returned to the depths of the earth. Instead, it collided with another ophioplite and was ultimately thrust up onto land. When the theory of plate tectonics transformed geological thinking during the second half of the 20th century, this giant anomaly became a destination for geologists eager to study a rare outcrop of rock from the mantle, including Kelemen. They also could have gone to New Guinea to look at a similar display of mantle rock or scattered sites in the western US, among other places, where ophiolites are present. But the Hajar Mountains comprise the biggest ophiolite of them all. Speeding carbon mineralization from geological rates to the pace needed to help stop global warming poses a fundamental problem common to unconventional oil and gas—creating flow paths in tight rock on a limited budget.