By Nick Fitzmaurice
Carbon Capture and Storage (CCS) is a seemingly well-intentioned approach to addressing the climate crisis where emissions are captured at the source (the smokestack of a coal plant) or directly from the air and deposited into permanent (usually geologic) storage to alleviate growing greenhouse gas concentrations in the atmosphere. However, while this technology has been promoted since the 1970s – largely by fossil fuel industries who serve to benefit from an excuse to keep burning their products – over 50 years of development have not been enough to turn this technology into a cost-effective solution to the climate crisis. Atmospheric removal of CO2 may be necessary in the global push for net zero greenhouse gas emissions, but this is distinct from capture at a source such as a coal-fired power plant or gas processing facility. Removal decreases CO2 concentration in the atmosphere, while capture at a source only partly reduces additional emissions into the atmosphere while that concentration continues to climb.The only applications of CCS that some might point to as “successes,” are where fossil fuel companies have monetized captured CO2, pumping it back into the ground to further stimulate oil and gas wells in an emissions-increasing process of enhanced oil recovery (EOR). This process, Carbon Capture Utilization and Storage (CCUS), actually increases overall emissions and is often erroneously equated to CCS. Now, fossil fuel companies are hoping to cash in on government tax credits to expand this market for captured CO2, regardless of whether efforts are actually effective at reducing greenhouse gas emissions. Meanwhile, fossil fuels could instead be replaced by highly cost-effective renewable electricity alternatives in wind and solar rather than taking the convoluted and expensive approach of capturing emissions and finding somewhere to permanently store them. CCS is an expensive and unproven band-aid fix on climate pollution that ignores the real possibilities available in a rapidly shifting energy landscape.
The purpose of CCS is to trap carbon dioxide (the primary climate-altering greenhouse gas pollutant) somewhere other than in the atmosphere. Generally, this practice assumes CO2 capture directly from large emissions sources, such as the smokestacks of a coal or gas fired power plant. Geologic CO2 sequestration pumps capture CO2 in a highly pressurized, nearly liquid state deep into the earth to trap it in a geologic formation. Theoretically, this CO2 would remain trapped in these formations permanently. As stated by the Intergovernmental Panel on Climate Change: “For well-selected, designed and managed geological storage sites, the vast majority of the CO2 will gradually be immobilized by various trapping mechanisms and, in that case, could be retained for up to millions of years.”
A Huge Price Tag for Montana
On paper, CCS seems like a swift way to sequester climate-warming gases underground or in other storage facilities where they will not contribute to further warming. Unfortunately, this process is both expensive and less effective than corporate greenwashers would like you to believe.
President Trump’s Department of Energy (DOE) calculated that the installation and operation of a carbon capture and storage system at the Colstrip coal-fired power plant would cost $1.3 billion (plus another $108 million a year for operation). This is 2018 dollars – a huge sum for a process that would only capture 63% of carbon dioxide emissions from the plant while lowering overall energy production. Meanwhile, the Environmental Protection Agency’s (EPA) 2024 greenhouse gas rule requires coal- and gas-fired plants to capture at least 90% of their emissions, a threshold that would cost much more to achieve at the Colstrip plant. DOE hid the numbers from its Colstrip analysis from the public for years, but after it failed to respond to MEIC’s Freedom of Information Act request in 2019, we sued. DOE finally revealed the estimated cost figure in October 2020, and it’s no surprise DOE wanted to keep a number that large a secret.
Environmental and Regulatory Hazards
Beyond the enormous price tag and small payoff, geological CO2 sequestration comes with certain hazards:
- Fractured rock formations, faults, and seismic activity could provide an avenue for CO2 leakage, nullifying the effort at sequestration.
- Pressure from CO2 injection could trigger small earthquakes.
- The cement caps usually placed on the wells could deteriorate when exposed to carbonic acid, which can form when CO2 interacts with saline formations.
- Abandoned oil and gas wells that were not sealed to today’s standards could leak. A sudden and large release of CO2 could pose immediate dangers to people in the vicinity.
- Elevated CO2 concentrations in the shallow subsurface could have lethal effects on plants and subsoil animals, and could contaminate groundwater.
- Carbon-laden liquids could mobilize toxic metals and organics and contaminate groundwater.
Despite these hazards, and despite substantial talk on the part of fossil fuel industries on wanting to pump carbon dioxide into geologic formations, there are limited regulations establishing guardrails and requirements for these projects, and no guarantee that carbon dioxide will be pumped into the earth in a safe and effective manner. Carbon capture has also proven to be too prohibitively expensive for fossil fuel companies to implement. Carbon capture and sequestration in Montana has not yet proven to be a viable, cost effective way for controlling our emissions.
Corporations Kicking the Ball Down the Road: ExxonMobil’s Pursuit of Billions in Tax Credits
If that weren’t enough, some corporations are beginning to exploit incentives for CCS.
Since issuing its geologic carbon storage policy for public lands in 2022, ExxonMobil Corporation (and its subsidiary Denbury Inc.) submitted two proposals to the Bureau of Land Management (BLM) for proposed carbon sequestration projects on BLM lands: one in southwest Wyoming and a second in southeast Montana with the theoretical combined potential to sequester upwards of 200 million tons of CO2 over the 20-year lifetime of the projects. However, it’s swiftly become clear that Exxon intends to cash out on federal carbon sequestration tax credits by simply moving CO2 from one geologic formation to another without actually mitigating the climate harms of CO2 emissions as the tax credit is intended. At $85 per ton of CO2, Exxon could theoretically rake in up to $17 billion in federal tax dollars from these two projects.
The project in Montana is the larger of the two, with CO2 sourced primarily from ExxonMobil’s Shute Creek gas processing plant in Wyoming, along with supplemental gas from Wyoming’s Lost Cabin gas processing plant. CO2 captured at these gas processing facilities is pulled directly from the ground and would not be entering the atmosphere if not for the operations at and upstream of these facilities. Specifically, the Shute Creek Treating Facility (SCTF) processes gas that is primarily CO2, not methane. In fact, this is the lowest methane-content fossil gas that is commercially processed for methane anywhere in the world, only made economically viable when there is a secondary market for the CO2 removed from the gas. Historically, that CO2 has been sold for Enhanced Oil Recovery (EOR) where it is injected into active oil wells to produce more climate-damaging fuels (with unsold CO2 vented directly into the atmosphere). With diminishing EOR markets, Exxon is now seeking a lifeline in these carbon sequestration tax credits.
SCTF was originally built with carbon capture technology, but over its lifetime it has vented approximately 50% of processed CO2 directly into the atmosphere, totaling over 130 million tons of CO2 emissions as of 2022. In the best-case sequestration scenario, SCTF capture technology would still emit about 2.5 million tons of CO2 annually, or 50 million tons of CO2 over the 20-year lifetime of Denbury’s sequestration project. This excludes other emission sources upstream and downstream of SCTF, such as CO2, methane, or other greenhouse gases leaking in gas extraction, gas transportation to SCTF, CO2 pipeline transportation, or long-term leakage from the geologic storage site. Denbury’s sequestration project enables and guarantees the continuation of all of these emissions sources.
To perform its exploitative maneuver, Exxon must transport compressed CO2 through pipelines more than 500 miles over land from its extraction site to the proposed injection wells in Montana. This poses tremendous safety risks as pipelines are prone to undetected leaks. Because isolated CO2 is heavier than ambient air, pipeline leaks accumulate in valleys and depressions, creating the danger of asphyxiation and death in these locations. CO2 pipelines already used for EOR in Montana have been known to rupture explosively, leaving craters on public and private land. Many landowners near existing and proposed CO2 pipelines in eastern Montana are extremely concerned about the risks of pipeline ruptures. One rancher filed a legal complaint against Denbury in 2023 citing the mismanagement of CO2 pipelines that caused 16 identified leaks and ruptures on his land over the course of a decade. A CO2 pipeline operated by Denbury in Mississippi ruptured in 2020 near a rural town, leading to hundreds of evacuations and nearly 50 hospitalizations.
Rather than energy-intensively capturing and sequestering some of the CO2 at these facilities, Exxon could instead thoughtfully plan for their decommissioning, replacing the energy production with cleaner, more cost-effective resources that embody a higher energy return on investment (the amount of energy produced, weighed against the amount consumed in its production). Exxon could cease operation at the Shute Creek gas proc
essing facility, saving taxpayers up to $17 billion dollars and directly mitigating the nearly 200 million tons of CO2 that would be processed at this facility over the projected 20-year lifetime of the proposed sequestration project.
