Carbon Kaboom

The Dangers of Carbon Capture and Sequestration

The aftermath of the Lake Nyos Disaster | Image: U.S. Geological Survey

On August 21, 1986, catastrophe struck the sleepy villages along the shores of Lake Nyos in the central African nation of Cameroon. A sudden limnic eruption released an enormous amount of carbon dioxide (100,000 - 300,000 tons) that had settled at the bottom of the lake into the surrounding atmosphere. The exact cause of the explosion is still a matter of dispute, but the effects were devastating. An estimated 1,746 people and 3,500 livestock were instantly killed by CO₂ asphyxiation.

Known as an “exploding lake,” Nyos is a rare body of water where heat and gases do not mix evenly, leading to two distinct layers: an upper, warmer layer with almost no CO₂ concentration, and a lower, cool lake bottom with very high CO₂ concentration. This phenomenon tends to occur in fresh water bodies near volcanic and seismic fault lines. These types of lakes are prone to periodic explosive expulsion of CO₂ , typically when the dissolved gas becomes highly saturated and is suddenly disturbed by nearby volcanic activity or land subsidence. Because CO₂ is 1.5 times heavier than air, its sudden, massive release produces a dense cloud that hugs close to the ground, traveling at high speeds through low-lying areas and displacing oxygen to higher elevations. This effectively deprives humans, livestock, and other land animals of breathable air, leading to suffocation.

In the wake of the Nyos disaster, the lake has been outfitted with specially designed degassing tubes to alleviate the pressure from CO₂ accumulation. Nearby lakes with similar characteristics, such as Lake Kivu in the Democratic Republic of the Congo, have also been investigated for their potential to cause eruptions. The “exploding lake” highlights the toxic and potentially lethal consequences of highly concentrated CO₂ .

Captured by Ideology

Which brings us to the topic of today’s story: carbon capture and sequestration technologies (CCS). Ostensibly, CCS is a method pushed by net-zero advocates to reduce industrial CO₂ emissions. CCS is “a three-step process, involving: capturing the CO₂ produced by power generation or industrial activity, such as hydrogen production, steel or cement making; transporting it; and then permanently storing it deep underground.” Critically, CCS requires the transport of liquified carbon via highly pressurized pipelines (2,000-2,200 psi) or compressed in tanker units (e.g., truck or ship transport). The end storage destination must be a deep deposit (minimum 0.6m/1km in depth), typically in saline aquifers or depleted natural gas or oil reservoirs. The infographic below depicts the stages of CCS:

CCS Stages | Source: Mahjour and Faroughi 2023

CCS has been featured heavily in recent news, as the U.S. Environmental Protection Agency (EPA) issued new rules in April requiring coal and gas plants “to meet a carbon dioxide emission standard equal to installing a carbon capture and sequestration system and running it at 90% efficiency,” beginning compliance in 2032. However, as CCS has not yet been proven at mass scale, these policy requirements are rushing headfirst into a potentially dangerous technology.

The Problem with Pipelines

The dangers and challenges associated with CCS are myriad. As alluded to in the description of the Lake Nyos disaster, one of the key concerns of CCS is the risk for ruptured pipelines and improper storage to ignite carbon explosions, potentially killing and maiming people and animals through suffocation and chemical burns. Pipelines in particular can release large amounts of CO₂ very quickly, and, as the gas is colorless and odorless, small leaks due to pipeline embrittlement may go undetected before large breaks occur if they are not properly monitored with leak detecting equipment.

One such event has already occurred. In February 2020, a carbon capture pipeline burst near Satartia, Mississippi when a weld failed following a period of heavy rain and a subsequent landslide. The rupture released 31,000 barrels of CO₂ into the air, leading to an estimated 10% CO₂ concentration in ambient air as far as one-half mile away from the explosion site. As the National Institute for Occupational Health and Safety (NIOHS) considers a concentration of only 4% to be “immediately dangerous to life and health”, this incident represented a serious risk to public health. Indeed, while there were no deaths reported, 45 people in the area surrounding the Satartia incident were hospitalized with symptoms of acute asphyxiation. Moreover, emergency vehicles were unable to respond immediately, as their internal combustion engines could not start in the oxygen deprived environment.

Lethal Injection

Another risk of CCS is groundwater contamination at injection sites. Poorly designed sequestration units may allow CO₂ to leach into surrounding aquifers, leading to acidification of drinking water. In fact, just earlier this month, the EPA issued a notice of violation of the Safe Water Drinking Act to a CCS injection well in Decatur, Illinois operated by the agribusiness Archer Daniel Midlands. The company was cited for corrosion in its deep wells (>5,000 ft) that allowed the CO₂ along with formation and injection fluids to migrate into areas where they were not permitted to go. This incident highlights the lack of regulation and oversight needed to make CCS a safe and effective technology. What’s more, current subsidies for CCS only require bidders to submit a 50 year plan for storage, when this carbon is supposed to be stored in perpetuity. Thus, companies are not required to consider events occurring at the geologic timeframe, such as deep well infrastructure decay, volcanic and seismic activity, and other natural subsidence over time. As the Illinois Clean Jobs Coalition stated in response to the Decatur incident, “there are significant risks at every step of the CCS process, and it's not a matter of if carbon sequestration facilities leak, but rather when.”

Not Ready for Its Close-Up

In addition to health risks, questions remain as to whether CCS actually reduces emissions at all. Even with heavy subsidies and research, development and demonstration (RD&D) support given to CCS start-ups by federal and state governments, some 80% of early stage funded projects have failed to commercialize. Furthermore, despite the EPA’s wishful thinking that every coal and gas plant will successfully use CCS technology at scale in less than a decade, no power plant to date in the U.S. has demonstrated its effectiveness. The most recent attempt was the NRG Petra Nova CCS plant in Texas, which was shuttered indefinitely in 2020 after it only captured 10-11% of the facility’s carbon emissions, with an initial goal of capturing 90% . A Stanford study reviewing the project’s failure concluded that the gas turbine used to run the CCS machinery had effectively negated any carbon offset. Another study at the New School for Social Research in New York corroborated Stanford’s findings, indicating that on a lifecycle analysis basis, CCS added more carbon to the atmosphere than it removed.

Finally, CCS in its current form is little more than a greenwashing scheme, as its primary use case is the injection of captured carbon into fracking sites to extract more gas and oil (also known as Enhanced Oil Recovery). For those opposed to the oil and gas industry to cheerlead for such a technology is either blind ignorance or the height of hypocrisy.

The serious inadequacies and flaws inherent in CCS technologies should be flashing red warning signs to the EPA that full steam ahead on such an untested and dangerous technology is a fool’s errand. After all, the tragedy at Lake Nyos reminds us of the potentially fatal ramifications of transporting and storing CO2 in highly pressurized, highly concentrated environments. But, while Nyos was an unexpected, violent act of nature, the carbon capture and sequestration technologies we flirt with today could be a disaster of our own making. As it ever was.

Electrically yours,

K.T.