Nebraska-led study eyes unique carbon dioxide storage option

The University of Nebraska–Lincoln’s Conservation and Survey Division is working with a national team of researchers to determine whether portions of Nebraska and Kansas may be suitable for permanently and safely storing commercial-scale volumes of carbon dioxide in rock layers deep underground.

The long-term goal of the Integrated Midcontinent Stacked Carbon Storage Hub project is to create an infrastructure in the central United States that collects carbon dioxide from facilities generating high emissions and delivers it to many possible storage locations.

The work, led by Battelle, an independent research and development organization based in Columbus, Ohio, is part of a two-year, $13 million award from the U.S. Department of Energy for its Carbon Storage Assurance Facility Enterprise, or CarbonSAFE, initiative. The initiative is meant to demonstrate that secure geologic storage of carbon dioxide captured from high-emission sources is commercially possible by 2025.

The Nebraska-Kansas project was the only one selected for a CarbonSAFE Phase II award that focuses on a regional hub storage solution. Other award winners address carbon capture from single facilities.

“One of the main reasons Nebraska is part of this study is because we are a major producer of ethanol,” said Dana Divine, Conservation and Survey Division hydrogeologist who is partnering with state geologist Matt Joeckel on the project.

Currently, carbon capture from ethanol plants is the most economical option because the emissions are relatively pure compared to other sources, such as coal-fired power stations.

“Ideally, many ethanol plants in Nebraska would contribute to this network,” Divine said. “After carbon-capture technologies advance enough to make capture from coal-fired power plants economical, those facilities could be added to the network.”

Research assessing the capture, utilization and storage of carbon dioxide has risen to the fore due to the recent expansion and reform in 2018 of a key tax credit, called 45Q, that incentivized carbon capture.

“Right now the tax credit alone may not be enough to fund construction of infrastructure to store carbon dioxide in saline formations,” said Andrew Duguid, senior research scientist at Battelle. “However, storage associated with CO2-enhanced oil recovery in old oil fields improves the economic picture by providing a commercial market for CO2.”

Duguid said carbon dioxide reduces the viscosity of oil trapped in the geologic formation, leading to increased oil production and increased storage.

“Although it may seem counterintuitive from a carbon-balance perspective to produce oil while storing carbon dioxide,” he said, “studies indicate that each ton of carbon dioxide injected for enhanced oil recovery results in a net abatement of at least 0.6 tons of CO2.”

Given the economics, the carbon dioxide in the regional hub likely would be stored in both oil- and non-oil-producing geologic formations.

In southwestern Nebraska and southwestern Kansas, the Conservation and Survey Division is examining whether two oil-field sites might be favorable for the storage of carbon dioxide. The researchers are studying the makeup of geologic units — about a half-mile to a mile below ground ― that contain very salty water; those units are completely separated from the much shallower groundwater used for drinking and irrigation.

“Our highest priority is protecting the groundwater that Nebraskans use, and that’s why we chose to be involved in this project,” Joeckel said. “By providing sound geologic and hydrogeologic data and analyses when major initiatives — such as this one — arise, CSD is fulfilling its mission to the state.”

The feasibility phase of the project is expected to be completed by the end of 2020, when the Conservation and Survey Division delivers its recommendations.