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DOE funds CO2 injection research UAF, Pacific Northwest National Laboratory researchers will investigate chemical swapping of carbon dioxide with methane in gas hydrate structures Patricia Jones PNA Contributing Writer
A three-year, $1.4 million research project mostly funded by the U.S. Department of Energy will investigate in a laboratory environment different methods of exchanging carbon dioxide for methane gas in underground gas hydrate structures.
Most of the funding, including $150,000 for the first year of the project, will come from cooperative agreement research money funneled through DOE’s Arctic Energy Technology Development Laboratory based in Fairbanks.
Researchers hope their project will provide some answers to developing an “economical and environmentally benign” method for recovering methane gas, an extraction process that could possibly be used in commercial development of North Slope gas hydrate structures.
“There are considerable resources of methane stored in gas hydrates, and scientists all around the world are studying these things,” said Pete McGrail, senior research scientist at Pacific Northwest National Laboratory, one of the research participants. “The amount of carbon trapped in gas hydrates exceeds all fossil fuels — oil, coal and conventional natural gas. It’s a tremendous resource if we can find a way to recover it.”
In theory, researchers will inject the CO2 into the ice-like solid gas hydrate structure, where it will swap places with methane, enabling recovery of the freed methane gas. The CO2 would remain sequestered in the hydrate structure, according to researchers.
The lab-scale methane recovery research, scheduled to start in December, will be conducted concurrently at the University of Alaska Fairbanks and at Pacific Northwest National Laboratory facilities in Richland, Wash.
In addition to investigating the basic chemical reaction of injecting CO2 into a gas hydrate structure, the researchers will be experimenting with some secret methods for speeding up the reaction process. Should those techniques prove to be successful, McGrail and his counterpart at UAF, Tao Zhu, Ph.D., would probably patent their process.
“There have already been some experiments in the lab with a slightly different system using this particular idea. It very rapidly destroyed the hydrate and re-formed the structure,” McGrail said. “It may not end up working but it shows pretty good promise. …we’re quite excited about that.”
Carbon dioxide-methane swap a basic chemical process According to the research project summary, scientists plan to study the behavior of methane hydrates when exposed to CO2 and determine how fast CO2 might replace methane under a variety of conditions.
McGrail described the swapping process as a basic chemical reaction, as CO2 hydrates are easier to form than methane hydrates.
“Chemically there is a thermodynamic principal that when CO2 is present, you have to have this swapping,” he said. “We’re looking at how long does it take for that reaction? If it’s a few seconds or hours, there is a basis for the process of going forward. If it takes years or decades, as we often see in subsurface science, we probably do not have a process that will work.”
But in addition to experimenting with different field conditions that might occur, the researchers will study mixtures of CO2 with certain gases and liquids as a possible means to control and perhaps accelerate the conversion process.
These accelerators involve the secret portion of the research project, McGrail said.
“We’re going to explore other ideas that could accelerate this process along, make it go faster,” he said. “It’s something we might want to be filing for a patent.”
Related but separate projects BP Exploration Alaska is also participating in the research project, in hopes that the laboratory-sized recovery research could be applied to a separate, BP-led gas hydrates project that involves resource characterization and quantification of this unconventional energy resource on the North Slope.
“Positive results from the UAF-PNNL project could impact the direction of the latter stages of the larger BP project in terms of a possible additional technique to consider for gas recovery mechanisms,” said Robert Hunter, BP’s Alaska gas hydrate project manager. “The use of CO2 as a potential recovery mechanism was never considered at the time of the original BP proposal.”
DOE is also partially funding the $18 million BP-led gas hydrate project, which will attempt to determine the technical and economic feasibility of recovering usable methane gas from the underground gas hydrate structures at Prudhoe Bay, Kuparuk and Milne Point.
Another related, but still separate, CO2-gas hydrate project remains in the conceptual stages.
Iain Wright, BP’s CO2 team leader for Alaska gas, has put together a project proposal that would take carbon dioxide emissions from a Milne Point gas-fired power plant and use them productively in enhanced oil recovery projects for viscous oil deposits.
In addition to reducing viscosity of the oil, CO2 swells when underground, so it would push the heavy oil out of its geologic formations, significantly increasing recovery from existing oil production facilities.
So far, BP has invested about $500,000 on preliminary engineering for the CO2 injection project, which would likely cost “tens of millions of dollars,” Wright told PNA this spring.
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