The potential for carbon sequestration locations in Iowa was the topic of a Science Café virtual discussion Tuesday, Nov. 28.
Ryan Clark with the University of Iowa, presented noting that there may be options for carbon sequestration in the state that do not need to involve large pipelines to haul away the carbon dioxide produced by ethanol and bio-diesel plants out of state.
Clark noted one form of carbon capture we’re all aware of is the process that is utilized in enhanced oil recovery, where the gases are pushed into an old oil reservoir or ground around a former well to help push oil to the surface.
Another place where to trap carbon sequestration is at coal mines.
“In that process, the carbon dioxide can be absorbed by the coal, but it will push up methane molecules towards the surface,” Clark said.
Iowa does not have shale or oil resources that would require the use of carbon sequestration for enhanced oil recovery. Some of the pipelines proposed in Iowa are headed for that use, however.
Clark said another option that could be considered is pushing the captured carbon dioxide 2,700 feet or deeper in the earth, primarily in a saline heavy aquifer system.
“The water has to be too mineralized to drink,” Clark said. “They’re looking for water that is 10 million parts per million that is sodium. That’s almost water you can chew.”
Clark said there are a few aquifers like that in Iowa, and they may be worth looking into if the goal is to capture some of carbon dioxide and place it somewhere.
The other area he was interested in learning more about is a practice happening in Iceland, which injects carbon dioxide into basaltic heavy areas focused on turning the liquid carbon dioxide back into a solid.
“In Iceland, they force the liquid into the basalt or lava areas, and that forces it from a gas into a solid again by mixing with those elements,” Clark said.
While Iowa doesn’t have any active fault lines or proximity to lava, there are some very heavy basaltic rock areas that might be worth looking into as storage projects.
Clark said he has been researching this as the Department of Energy has said their goal is to have 600 sites that would be needed to sequester the carbon emissions in the future, and they only have five now.
“I don’t see how they can get to 600 carbon sites without incorporating Iowa in to some of that,” Clark said.
Currently, Iowa’s biodiesel and ethanol plants generate 4.5 billion gallons of CO2 per year. Locations like California, Washington and Oregon want fuels to have a lower carbon threshold, which is why many biodiesel plants are pursuing pipeline projects to take some of that carbon and utilize it in either storage underground or for use in extraction of oil in other locations.
Clark’s hypothesis to be explored is the Mount Simon Aquifer as it stretches into Iowa. A portion of the Wolf pipeline is taking carbon from the Cedar Rapids ADM plant and Clinton ADM plants to that aquifer for potential storage.
“We know that the porosity in Mount Simon in the Illinois Basin is 25 percent, which means it should be a good solution for carbon sequestration, but we don’t know that porosity on the Iowa side,” Clark said.
Permeability refers to the ability for gases to escape from a location. Porosity is if something is absorbent.
Iowa, despite not having an active volcano, does have remnants of a rift through a good portion of the state. That mid continent rift is another area Clark would see as a possibility to see if it has high basalt basins that might make an ideal location for carbon sequestration. He noted the Eischeid project in Carroll County went more than 17,000 feet deep at one time, and found red clastic rocks that had a one to six percent porosity.
What’s more, more than half of the ethanol or biodiesel plants in Iowa sit on the basalt region of the state.
Research into that project could take upwards of three to four years to complete with federal funding, or with a significant donor in the state of Iowa, sooner. Any study into that region would need samples of ground water and rocks, and then a geographic modeling to show how viable carbon sequestration would be.
One area of concern raised during the question and answer period was the high amount of water required for carbon sequestration to begin with and how that could impact aquifers in the state used for this process.
“If that proves to be a significant hurdle on how much water is used for some of these projects that we can’t get over, then these projects should definitely not be considered,” Clark said.
Another issue is how prolonged exposure to carbon dioxide underground could change characteristics of these rocks or groundwater. Clark said that too is definitely an area for study.
A questioner said that geologic storage is unproven, which Clark pushed back against.
“We’ve been doing a form of geologic storage in other ways since the 1970s,” Clark said. “We have a firm understanding of that process. If we can capture CO2, we should look at the options to do so.”
The Environmental Protection Agency would have to regulate any underground injection and permits would be required, as well as owners of the well/location compensated.
Questioners also asked about the potential of prairie restoration helping to reduce the carbon output.
Clark noted his expertise is geology, not ecology, but if there was any benefit, that is something that should also be researched.