Two Kansas State University geologists are part of a comprehensive statewide study on using rocks for long-term storage of carbon dioxide.
Carbon dioxide is a gas that is a
byproduct of respiration and burning fossil fuels and heat sources, among other
causes. Studies have linked increased carbon dioxide production to climate
"Currently, more carbon dioxide is
being produced by various sources, both natural and anthropogenic, and is going
into the atmosphere," says Saugata Datta, assistant professor of geology
who is leading the university's involvement in the project. "This study is
not to look at what carbon dioxide does to the atmosphere, but rather how to
sequester it and keep it from reaching the atmosphere in the first place."
Datta and Robin Barker, master's student
in geology, Arnoldsville, Ga., are studying the geochemical effectiveness of
trapping and storing carbon dioxide by injecting it more than 5,000 feet
underground in the Arbuckle aquifer under Kansas. The aquifer has a thick layer
of porous rock that scientists believe could permanently store carbon dioxide.
It also contains ground water with such high salt concentrations that the U.S.
Environmental Protection Agency has deemed it unsafe to drink.
According to Datta, determining whether
the rocks of the Arbuckle are effective for permanently storing carbon dioxide
could be beneficial to manufacturing and production industries, which currently
monitor carbon dioxide production levels due to regulations.
The aquifer is one of 10 throughout the
nation that is being studied. Scientists from other national institutions and
universities are conducting similar projects in Alabama, California, Colorado,
Illinois, New Jersey, New York, South Carolina, Texas, Utah and Wyoming.
The study at Kansas State University is
threefold. For the first portion -- already in progress -- Datta and Barker are
using water and rock core samples from the aquifer to look at the mineralogical
composition of deep formation waters and rock, as well as how they interact.
Ion chromotography and mass spectrometers are being used to study the organic
and inorganic components of the water.
"We're essentially tearing apart a
drop of water for analysis," Datta says. "Water is a really great
indicator of what's going on in the subsurface. It also indicated delicately
what can happen in the subsurface after injection of carbon dioxide. By
studying it, we can understand where it comes from, how the change in
environment from adding carbon dioxide affected it and what will happen over a
long period of time."
The second phase centers on storage --
injecting carbon dioxide into aquifer rocks. Researchers are using drill core
samples collected from the aquifer, along with brine and carbon dioxide, to
geochemically model what happens when carbon dioxide is injected into the
aquifer rocks. With this, researchers can look at what happens to the ground water
before, during and after the carbon dioxide injection. Additionally, they can
predict what will happen to the stored carbon dioxide decades into the future.
"We're really looking into the
geochemical feasibility of this as a solution," Barker says. "So far,
the preliminary conclusion is that geochemically, it appears that we will be
able to safely sequester the carbon dioxide in the aquifer without affecting
any drinking water sources."
The project will enter its third phase
beginning January 2013 with a large-scale experiment in Wellington. Researchers
will inject 40,000 metric tons of compressed carbon dioxide 5,000 feet below
the Arbuckle aquifer and 30,000 metric tons of carbon dioxide into an overlying
oil reservoir. Various sampling techniques will be used to study and model the
carbon dioxide and its lifespan in the aquifer.
"It has already been proven that
certain minerals within rocks, such as silicates, are able to trap carbon
dioxide and transform it into a solid mineral," Datta says.
"Ultimately what that means is that once the carbon dioxide is trapped as
a mineral, there is very little chance of it being dissolved and being released
into the atmosphere. This is essentially locking it up forever."
The injection test will continue until
May 14, 2014.
In addition to Kansas State University,
scientists collaborating on the Kansas project are from the Kansas Geological
Survey, headed by Lynn Watney, geoscientist and project manager; University of
Kansas; Wichita-based BEREXCO Inc.; Lawrence Berkley National Laboratories; and
Sandia Technologies. Each institution is looking at a different aspect of the
carbon dioxide sequestration, such as drilling and evaluating wells; monitoring
the carbon dioxide plume; injecting carbon dioxide in an oil reservoir to test
oil recovery; and ensuring containment of the carbon dioxide from leaking to
Carbon dioxide will be transported by
Abengoa Biofuels from an ethanol plant in nearby Colwich.
For its portion, Kansas State University
was awarded four separate grants from the U.S. Department of Energy, totaling
more than $800,000 throughout the course of the study.
The project will end, and results will
be released, in 2015.
Testing Aquifer Rocks for Carbon Dioxide Storage
July 9, 2012