Getting down with CO2

Illustration: Sandbox Studio

Getting down with CO₂

When Princeton University geoscientist Catherine Peters learned about a plan to build the world's deepest science laboratory in an abandoned gold mine in South Dakota, she saw a chance to tackle an urgent challenge: how to store carbon dioxide deep underground so it can't escape into the atmosphere and contribute to global warming.

Peters and colleagues from Princeton and Lawrence Berkeley National Laboratory hope to carry out their DUSEL CO2 project at the proposed Deep Underground Science and Engineering Laboratory, which will host research in physics and a wide range of other fields.

“The geology of the Homestake Mine is not what we're interested in,” Peters says. “Instead it's the depth.”

In the mine's roomy interior, scientists plan to build models of the kinds of geological structures that are being considered for carbon storage, says Curtis Oldenburg, leader of the Berkeley Lab contingent. These “flow columns” aren't miniatures. Taller than the Empire State Building, packed with layers of sand and clay and filled with brine or other fluids, they will allow researchers to see what happens to dense CO₂ injected at different temperatures and pressures. They want to know if the CO₂ will stay deep underground, and what happens if it leaks out.

The Houston-based company Schlumberger, a leader in deep monitoring technology in the oil and gas fields and DUSEL CO2's industrial partner, works in far deeper wells across the world. But with a well, the only way in is from the top. The Homestake Mine's shafts and drifts will allow access from top to bottom, revealing at what point the CO₂ changes phase from a liquid to a gas, whether the paths it takes through fractured shale or cement well linings get bigger over time or seal themselves, and what role microbes play in converting CO₂ to other gases or minerals.

Open to scientists from all over the world, DUSEL CO2 will allow scientists to model the deep Earth on a scale a bit smaller than Earth itself.

Paul Preuss