Two new grants from the Department of Energy (DOE) Office of Science will help expand earth scientist/Ohio Research Scholar David Cole’s deep-earth energy research, which centers on the problem of geologic carbon sequestration and hydrocarbon exploration and exploitation.

“Our work is driven by the world’s increasing energy demands and the clear need to mitigate its environmental impact,” Cole said. “We are looking for better ways to store CO2—answers to where we can put it safely and how we can best optimize the process.”

Cole is gratified to receive these awards; the first is a three-year, $240K grant that funds efforts to characterize nanoporosity in representative caprocks, using neutron scattering in concert with electron microscopy.

Exploring the porosity and permeability of caprocks, rock layers that have the ability to hold liquids without leakage, are key variables that link to its sealing properties. The overarching goal is to determine how nanoporosity evolves in reacted systems at conditions relevant to subsurface CO2 injection. These investigations are a critical step in determining the potential of underground carbon storage.

“There are lots of different ways to capture CO2 and mitigate its effects,” Cole said. “Geological formations offer safe possibilities.”

Researchers are hoping to take advantage of established fields and wells for storage. But the challenges are enormous; it’s important to be able to predict what happens a thousand years from now, and upwards.

And, the need to tackle those challenges, such as power plant emissions—each of which pumps 5-8M tons of CO2 into the atmosphere each year—is now.

Results from the second project, a three-year, $450K award for studies of nanopore confinement of C-H-O mixed-volatile fluids relevant to subsurface energy systems, will have impact on DOE’s Office of Basic Energy Sciences Geosciences mission to:

• characterize emergent nanoscale features of fluid confinement that control the macroscopic thermodynamic and kinetic properties of bulk minerals and fluids;
• quantify atomic to nanoscale reactivity, structure and transport properties at the fluid-solid interface;
• delineate the rates and mechanistic pathways that can arise from different kinds of perturbations that lead to both near- and far from equilibrium conditions.

“The behavior of hydrocarbons in Earth’s crust is part of what we’re probing,” Cole said. “We are using bench scale experiments, spectroscopic probes and molecular-level modeling to interrogate the interaction of simple and complex C-H-O fluids with key mineral phases from ambient to extreme pressure-temperature conditions consistent with depths of 10’s of km.”

Cole, who does not define himself as a traditional geologist, has a strong physical chemical background. “Knowledge of chemistry and physics allows us to be predictive using a number of different tools, such as neutrons, x-rays, and NMR to better understand those interactions where you could say, earth sciences meets chemistry and physics.

"This work benefits enormously from a collaboration with OSU Co-PI Professor David Tomasko, Department of Chemical and Biomolecular Engineering, who has unique capabilities to measure and model sorption of fluids on mineral substrates at elevated pressure and temperature.

“This is where the action is—in the pores of rocks and at mineral surfaces. By characterizing the material, and seeing how fluids are filling the pores, we can get a sense of what happens at that scale.

“There are many aspects of the behavior of hydrocarbons formed via unconventional mechanisms in Earth’s crust and mantle we still do not understand. Further, there are a few large economic gas deposits in Siberia and China that have very unusual chemical and isotopic characteristics that suggest a deep Earth source rather than the typical biogenic origin.

"The existence of these deposits is forcing us to re-evaluate what we know about hydrocarbons and how they form. We are interested in putting this into the larger framework of the global carbon cycle where we need to understand carbon behavior over extraordinary length and time scales.”

Cole believes that unconventional resources can be used to understand fundamental behavior. And, a more specific look nearer the surface can link to deeper levels and play off of how carbon behaves overall, giving a quantitative view of the cycle in space and time.

This new effort is complementary to work funded by a 1.5 M Sloan grant Cole received in July, 2011. The Sloan grant funds Cole’s leadership of a multidisciplinary, multinational team from seven countries, as well as a national network of postdoctoral researchers. This team will do extensive research on fundamental mechanisms and rates that control the chemical and isotopic compositions attendant with carbon-bearing fluid-rock interactions, over the next several years.

Their work holds promise for answers to these challenges.