Infrastructure protectionAbandoned mine offers clues about permanent CO2 sequestration
Power plants and other industries are responsible for more than 60 percent of global CO2 emissions, according to the International Energy Agency. Sequestering the CO2 in magnesite deposits would prevent the gas from entering the atmosphere and warming the planet. Stanford University researchers, studyingveins of pure magnesium carbonate, or magnesite — a chalky mineral made of carbon dioxide (CO2) and magnesium – in an abandoned mine in the Red Mountain, propose a novel technique for converting CO2 into solid magnesite, making CO2 sequestration feasible.
An abandoned mineral mine near Stanford University is providing geoscientists new insights on how permanently to entomb greenhouse gas emissions in the Earth.
For two years, a team of Stanford researchers has been trying to unravel a geological mystery at the Red Mountain mine about seventy miles east of the campus. The abandoned mine contains some of the world’s largest veins of pure magnesium carbonate, or magnesite — a chalky mineral made of carbon dioxide (CO2) and magnesium. How the magnesite veins formed millions of years ago has long been a puzzle.
A Stanford University release reports that the Stanford team has now proposed a solution. Their findings could lead to a novel technique for converting CO2, a potent greenhouse gas, into solid magnesite. The results were presented last month at the 2013 fall meeting of the American Geophysical Union (AGU) in San Francisco.
“Conventional geological storage involves capturing CO2 from industrial smokestacks and injecting it as a fluid into the subsurface,” said Kate Maher, an assistant professor of geological and environmental sciences at Stanford. “But there is concern that the carbon dioxide would eventually leak back into the atmosphere. Our idea is to permanently lock up the CO2 by converting it into a stable mineral.”
Power plants and other industries are responsible for more than 60 percent of global CO2 emissions, according to the International Energy Agency. Sequestering the CO2 in magnesite deposits would prevent the gas from entering the atmosphere and warming the planet, Maher explained.
Magnesite mining
Magnesite was used in the early twentieth century for iron smelting and manufacturing cement. The Red Mountain mine operated for about fifty years until the late 1940s.
At Red Mountain, the Stanford team has identified more than twenty large veins of pure magnesite embedded in magnesium-rich ultramafic rock. The biggest vein is about 118 feet wide and 886 feet long. More than 50 percent of the magnesite in each vein consists of CO2, the rest is magnesium.
Ultramafic rocks make up about 1 percent of the Earth’s surface and occur near regions undergoing rapid population and industrial growth, Maher said. More than fifty other deposits of exceptionally high-grade magnesite are distributed in the California Coast Ranges alone.
Sequestering CO2 emissions at these sites could play a significant role in curbing global warming, she added.
