Carbon dioxide sequestration in Iowa? Researchers hope to find out

Aided by more than $11 million in grant funding, researchers plan to build a huge drilling rig and determine whether carbon dioxide can be permanently stored underground in Iowa — even though the state’s geography was largely thought to be ill-suited for sequestering the most common greenhouse gas.

CO2 sequestration has been a hot topic in the Midwest as three companies have floated plans to build underground pipelines in the region that would capture emissions from ethanol plants — many of them in Iowa — and move the liquefied gas to be injected deep underground at sites outside Iowa.

While these pipelines have drawn much attention in the Midwest, thousands of miles of CO2 pipelines are being built elsewhere in the country to suck carbon dioxide emissions from power plants and factories and store it underground rather than emit them into the atmosphere — pipeline construction encouraged by tax breaks seeking to slow climate change.

This month, the University of Iowa was selected to lead a two-year study about how CO2 is managed in the state. The U.S. Department of Energy is funding $9 million of the study and MidAmerican Energy — which has a coal-fired power plant in Council Bluffs that will be central to the study — will cover the majority of another $2.3 million.

The study will look to see if CO2 can be stored in a particular type of rock found in the Midcontinent Rift system, where the North American continent was splitting apart more than a billion years ago.

“This type of experimentation has never been done,” said geologist Ryan Clark, whose team at the UI-based Iowa Geological Survey will lead the study beginning next fall. “It's going to be devastating if the answer is that nothing happens. (But) the ideal scenario is that a facility that generates CO2 can just capture it on site, inject it on site, with no pipeline. … That's the ideal scenario.”

How it will work

The research will look into whether CO2 can be sequestered into basalt rocks. Underground sequestration is practiced widely, but it mostly has used depleted oil and gas reservoirs — and it has not been widely tested with basalt.

Clark said field studies in other states have suggested that when liquefied CO2 is injected it into the basalt rock, it eventually becomes a mineral — whereas it remains a liquid in other types of rocks.

  Buy Photo

In this case, the rocks at the Council Bluffs site are 1.1 billion years old. The team’s hypothesis is that the carbon dioxide will mineralize inside the rocks over a few years, so the liquefied CO2 won’t have to be put into pipelines spanning several states.

Clark said a major benefit of a mineralized CO2 in the basalt would be that there is minimal worry about what it would do over time.

“Eventually it just all converts to the mineral calcite. I call it Iowa diamonds,” Clark said. “Calcite is really common. It's what limestone, fossil shells are made of it. … They’re really stable minerals.“

Clark said for the study to work, drilling to a specific depth is key.

“CO2 is naturally a gas and it has to be compressed,” he said. “Once it's captured, it has to be compressed so that it goes from a gas to a liquid, and then it has to stay under that pressure to stay a liquid.”

Clark said the “magic number” for liquefied CO2 to remain a liquid is about 2,700 feet down into the Earth. So the hole has to go deeper for the liquid to become a mineral.

Clark said rocks are like sponges and have open spaces inside. With their study, researchers will be examining the basalt rocks — which are volcanic rocks formed from rapidly cooled lava — to see if they have the storage capacity for the injection.

To extract samples of the basalt rocks, Clark said the researchers anticipate drilling 5,000 feet deep. From there, they will use a “cylindrical drill” to pull core samples to the surface. Clark compared it with pulling a school bus out of the ground.

Once the cylinder-shaped hole is made and the basalt samples are out, the team will send an instrument down the hole to X-ray the rocks and document what’s present.

Most of the grant money will go toward custom building a drill rig big enough, Clark said. But the study also will entail laboratory analysis and computer modeling work.

He said researchers will inject a small amount of carbon dioxide into the basalt to document any reactions or changes within the rock, and to see how long it takes for the liquid CO2 to mineralize.

Clark said there have been studies in Washington state and in Iceland that have studied this concept, to an extent.

“This is the first time we're looking in Iowa, so we don't really know,” Clark said. “Everything to this point is theoretical.”

  Buy Photo

An ‘important project’

Geoff Greenwood, media relations manager for MidAmerican Energy, said the study will be conducted at MidAmerican’s Walter Scott Jr. Energy Center in Council Bluffs.

“MidAmerican is pleased to assist the Iowa Geological Survey with this project," Peggi Allenback, a senior vice president for MidAmerican said in a statement. "If the study succeeds, it could open the door for a new method to reduce carbon emissions.”

  Buy Photo

Greenwood said MidAmerican views the study “as an important project that will help researchers determine whether carbon storage in the basalt formation deep below our facility is viable. If the study ultimately succeeds, it could potentially lead to a new option for diverting and permanently storing carbon dioxide emissions.”

When the study is completed, Clark said the drill rig will be deconstructed and moved to new locations to be rebuilt.

A hot-button issue

The study comes as conversations around CO2 pipelines are continuing to be a hot-button issue nationwide.

Iowa regulators earlier this year granted Summit Carbon Solutions a permit to build an initial phase of its pipeline in Iowa, provided it also obtains permission from the four other states it plans to partially cross — the Dakotas, Nebraska and Minnesota. Friday, North Dakota regulators reversed themselves and approved a permit for the route in that state. But the company needs other approvals to proceed.

Another CO2 pipeline company, Wolf Carbon Solutions, proposed connecting Eastern Iowa ethanol plants — including one in Cedar Rapids — and sequestering the CO2 in Illinois. But the fate of that pipeline remains unclear.

A third company that planned to build a CO2 pipeline in Iowa, Navigator Heartland Greenway, cited an “unpredictable” regulation and approval process and in 2023 pulled the plug on its proposal.

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; olivia.cohen@thegazette.com