NETL Adopts Medical Technique to Study Mobility of CO₂ in Coal

	Robert McLendon of the Office of Research and Development at the Department of Energy’s National Energy Technology Laboratory adjusts the CT scanner used in research at NETL. The scanner is used to measure in situ fluid displacement and sorption of fluids within mineral cores.

Computed tomography – you may be more familiar with the term CT scan – is usually thought of as a medical technique, but researchers at the Department of Energy’s National Energy Technology Laboratory are using CT to assess the potential long-term storage of carbon dioxide (CO₂) in deep, unmineable coal seams.

A paper describing the approach and the observed results has been accepted for publication in the peer reviewed journal, SPE- Reservoir Evaluation & Engineering-Reservoir Engineering.

CO₂ concentration gradients were determined at the confining and pore pressures of the deep strata.  For those evaluating the potential of sequestering CO₂ in such coal seams, this technique provides realistic and essential design information regarding flow and sorption rates and limits of CO₂ sorption.  The data can then be used in numerical simulations to predict results for target coal seams.

NETL researchers are looking at various ways to keep carbon dioxide from getting into the atmosphere.

One option for storing carbon dioxide permanently is to inject it into coal seams where it would be trapped inside the coal.

The CT research is used to study the effects of carbon dioxide injection into coal seams, and the implications for additional storage of carbon dioxide. When carbon dioxide is injected into a coal seam, it is sorbed – taken up by the coal through absorption or adsorption and held.

Research performed at NETL on the effects of carbon dioxide sorption demonstrates that under some circumstances, sorption can cause the coal to swell, and make it more difficult for additional carbon dioxide to be stored.

However, NETL research also has shown that carbon dioxide sorption can cause fractures to develop in the coal, which would make the injection easier. This finding apparently has been confirmed by field tests around the world; in some cases, carbon dioxide injection caused the injectivity to increase.

NETL Makes First Measurements in Unique Oxy-Fuel Flame Test Facility

	Joe Yip, left, and Ben Chorpening, researchers in NETL’s Office of Research and Development, prepare to conduct an experiment in NETL’s unique oxy-fuel flame test facility. The color of the oxy-hydrogen flame is due to the presence of steam. This research by NETL has yielded what are believed to be the first measurements taken in such high steam conditions.

Researchers at the Department of Energy’s National Energy Technology Laboratory are not quite trying to start a flame underwater and keep it burning, but some of their recent research isn’t far from that.

NETL researchers in the Energy System Dynamics Division of the Office of Research and Development have taken measurements of an oxy-hydrogen flame in an environment where the amount of steam may be as high as 70 percent of the gas.

Kent Casleton says these may be the first measurements taken in such high steam conditions.

The measurements were made during experiments in NETL’s unique oxy-fuel flame test facility.

Oxy-fuel combustion schemes are being considered as a mitigation strategy to more efficiently reach the goal of zero emissions of carbon dioxide (CO₂) from combustion of fossil fuels. This approach is attractive because the major products of combustion in oxy-fuel systems are CO₂ and water.  CO2 can be separated simply by cooling the combustion products to condense out the water, yielding a concentrated CO₂ stream for subsequent sequestration.

Since nitrogen is removed from air to produce oxygen for the oxy-combustion, a diluent (diluting agent) such as steam, CO₂ or flue gas (steam plus CO₂) must be added to prevent overheating of these hydrogen-oxygen flames. That’s because 80 percent of regular air is nitrogen, which has a heat capacity that affects the flame temperature. Without the nitrogen, the temperature is higher.

In some cases, added diluent such as steam can represent up to 70 percent of the volume of the input gas flow to the burner. The studies provide valuable information about lighting and sustaining a flame in such a high steam environment.

There is little data available in the literature to enable design of oxy-fuel combustion systems.  The successful testing at NETL represents an important step toward the goal of measuring flame speeds and radiative properties of these flames, which are needed to accurately simulate and design advanced power systems for carbon sequestration.

NETL, WVU Collaborate to Produce New Analytical Device

Researchers at the Department of Energy’s National Energy Technology Laboratory and West Virginia University have collaborated to produce a portable micro-indenter that can provide non-destructive analysis of properties of a variety of materials.

In conjunction with Mary Anne Alvin of NETL’s Materials and Component Development for Advanced Turbine Systems project, Dr. Bruce Kang, Dr. Tong Feng, and Mr. Jarred Tannebaum at WVU developed not only the methodology, but also a series of micro-indentation systems for determining the stiffness of metals, superalloys, single crystal matrices, and coated material systems.  These properties were previously determined through destructive analysis.

The collaborators originally developed a table top unit, and more recently they have developed portable and hand-held units.  The compactness of the newly developed portable unit facilitates testing in either the research laboratory setting or at field sites. The unit can be used with flat, tubular, or curved architectures.

These are the three types of micro-indentation systems produced through a collaboration between NETL and West Virginia University.