Category: Lecture

Calendar View >>

Event Details

CIRES Distinguished Lecture Series

Fri Mar 12, 2010. 04:00 pm - 05:00 pm
CIRES Auditorium

In situ mineral carbonation in peridotite for geological capture and storage of CO2

Dr. Peter Kelemen, Columbia University

The rate of natural carbonation of tectonically exposed mantle peridotite during weathering and low-temperature alteration can be enhanced to develop a significant sink for atmospheric CO2. Natural carbonation of peridotite in the Samail ophiolite, an uplifted slice of oceanic crust and upper mantle in the Sultanate of Oman, is surprisingly rapid. Carbonate veins in mantle peridotite in Oman have an average 14C age of 26,000 years, and are not 30–95 million years old as previously believed. These data and reconnaissance mapping show that 10^4 to 10^5 tons per year of atmospheric CO2 are converted to solid carbonate minerals via peridotite weathering in Oman. Peridotite carbonation can be accelerated via drilling, hydraulic fracture, input of purified CO2 at elevated pressure, and, in particular, increased temperature at depth. After an initial heating step, CO2 pumped at 25 or 30°C can be heated by exothermic carbonation reactions that sustain high temperature and rapid reaction rates at depth eliminating the need for continued heating. A potential problem is that crystallization of carbonates could fill pore space, reducing permeability and armoring reactive surfaces. However, large increases in the solid volume due to mineral carbonation may create stresses that fracture the rock, maintaining permeability and reactive surface area, eliminating the need for additional hydrofracture. Abundant, fully carbonated peridotites provide geological evidence that this can occur. Thus, in situ carbonation of peridotite could consume >1 billion tons of CO2 per cubic kilometer of peridotite per year, affording a low-cost, safe, and permanent method to store CO2.

An alternative to using purified CO2 would be to use surface seawater as a CO2 transport fluid, and inducing convection through peridotites that are already at high temperature, as for peridotites exposed on the seafloor near the volcanically active mid-ocean ridges. Use of seawater rather than CO2 fluid would result in 100 to 1000 times slower reaction rates and thus diminished exothermic heating, requiring more drill holes to access more rock in order to achieve the same rate of CO2 uptake per year. However, use of seawater would provide a mechanism for "negative CO2 emissions" - unlike CO2-capture from fossil fuel power plants -, and would avoid the costs of industrial CO2 capture, CO2 transport, heating a sub-surface rock volume, and compressing CO2 fluid. About the Lecturer

Peter B. Kelemen is the Arthur D. Storke Professor of Geochemistry in Columbia University's Department of Earth and Environmental Sciences, based at Lamont Doherty Earth Observatory. He is also a Research Associate at the American Museum of Natural History, and an Adjunct Scientist at Woods Hole Oceanographic Institution (WHOI). He came to Lamont-Doherty in 2004 after 17 years in Woods Hole where he was Charles Francis Adams Chair. He has worked on the mantle "plumbing systems" of volcanoes, and on the genesis and evolution of oceanic and continental crust. Since moving to Lamont, he continued this work but also began research on the deeper parts of earthquakes and most recently on CO2 capture and storage via in situ formation of carbonate minerals in rocks. Though he is new to this field, his work on reactive transport of CO2 in rocks follows naturally from prior work on transport of lava. Kelemen was a founding partner of Dihedral Exploration, consultants specializing in mineral exploration in steep terrain, looking for copper, gold, and platinum group elements from 1980-1992. Research, consulting and climbing have taken him to Greenland, Peru, India, Oman, the Aleutian Islands, 7500 meters above sea level in Pakistan, and 5500 meters below sea level via submersible along the Mid-Atlantic Ridge. He is a Fellow of the American Geophysical Union (AGU, 2004) and the Mineralogical Society of America (2006), and received the AGU Bowen Award in 2004. He attended Wilmington Friends School in Delaware, and later received a B.A. from Dartmouth College (1980), followed by an MSc and a PhD (1987) from the University of Washington.

Websites: CIRES

Want to automatically follow our news and events without having to visit the ENVS website with your browser? Just subscribe to one of our news and calendar feeds.

What is an RSS news feed?

About:

- Faculty Focus -

Deserai Crow

Environmental policy and the role that mass media and other factors play in policy decisions.

- Featured Image -

Beth and Caitlin