SIOUX CITY, Iowa — The two carbon-capture pipelines in the works from Summit Carbon Solutions and Navigator CO2 Ventures will carry pressurized carbon dioxide hundreds of miles across 6 states. While the technology for these pipeline infrastructures has advanced and improved, a rupture is always a possibility.
"The consequences to the land agricultural production lies and examination afterward, there's not much research done on that specific type of spill. Finding it in the literature is incredibly hard if it even exists, but there are a few things that we can expect for when that happens." Aaron Daigh is a land and soil expert who has studied pipeline ruptures and the impact they can have on the land.
"You would expect whatever zone that supercritical carbon spread out on in the ground, is likely stripping out some of the nutrients and fertility of that ground and so in addition to that microbial part, you would see a reduction and productivity or that's what you would expect to occur." Supercritical carbon refers to pressurized carbon dioxide that is different from the pure liquid state. This CO2 is not really a liquid, not really a gas, it's kind of in-between, sharing properties with both states.
"One of the things too is that when a rupture occurs in these supercritical states because the pressures suddenly change, the temperature drops dramatically," said Daigh. "So it will essentially flash freeze the ground around it, which is a hazard in itself if you're close by it, but it also jeopardizes more of that it makes the rupture larger."
Let's back up a bit. Carbon dioxide itself isn't considered a contaminant. It's in the soil. It's in the air we breathe. But it's when you get it in high concentrations, that it can turn toxic, even deadly.
The pressure when it gets released, it can cause the supercritical carbon dioxide to enter into the ground and spread a particular distance. The longer the pressure hasn't been turned off of the pipeline, the larger and the wider that that's going to get.
And the danger that poses is not just for humans. "One of the things is that because of that extreme temperature shift, biology is going to respond to that," said Daigh. "And in a lot of these areas, the ground freezes during the winter but the degree of freezing is very different than the temperature change that you would see from a pipeline break."
So what happens when a carbon dioxide pipeline ruptures or leaks? How big of an area could be impacted? Daigh says it depends on how long it takes to notice it. He points to an oil pipeline rupture in North Dakota as an example.
"Maybe a quarter-inch diameter hole either from corrosion or something else in our pipeline occurred," said Daigh. "And it wasn't noticed until some of the product that was going through it was actually ponding on the surface. So not only did it move down in the ground but built up and then ponded above it so it took a while to even notice."
The aftermath of that rupture lasted years. "Just the remediation process to dig out the contaminated sediment that went down about 60 feet over about 70 acres. The remediation process just to clean it up and put the ground back took about six years to occur and cost approaching $100 million."
While that's the worst-case scenario, Daigh says even with smaller leaks there are things landowners can do.
"Something that I would recommend to landowners if there was ever a break on the property is that in the site investigation afterward to see what the disturbed area or contaminated area is, to not look just where the extent of the carbon entered into the ground, but also a little bit beyond it. You know, give it another 20-30-40 feet worth of sampling to see, because whatever was in the zone that that carbon moves through, the supercritical carbon dioxide, whatever it stripped out, it's going to deposit wherever it's stopped moving at," Daigh said.
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