Why CO₂ Pipes Deserve Extra Concern
Pipelines are usually sold to the public as boring, sensible bits of infrastructure. Steel tubes. Valves. Clipboards. Nothing to worry about. CO₂ pipelines, however, are not quite that sort of pipe.
At first glance, the pitch sounds reassuring: “It’s just like other gases under pressure. We already move high pressured gas across the country. What’s the difference?”
The difference is what CO₂ does under pressure — and what happens when things go wrong.
CO₂ Is Not “Just Another Gas”
Most people are familiar with natural gas pipelines. Methane leaks are dangerous, yes — but they behave in predictable ways. Gas rises, disperses, and (very obviously) smells.
CO₂ behaves differently.
In CCS schemes, CO₂ is transported at very high pressure, often in a supercritical state — not quite a gas, not quite a liquid. In this form, it is dense, aggressive, and chemically active. It also has an unfortunate party trick: when released suddenly, it expands violently and pushes oxygen out of the air.
No smell. No warning. Just air that no longer keeps you alive.
When CO₂ Leaks, It Doesn’t Float Away
A methane leak rises. CO₂ does the opposite.
CO₂ is heavier than air. In the event of a rupture, it can pool at ground level, flow into dips, trenches, basements, or low-lying land, and sit there quietly doing what CO₂ does best: displacing oxygen.
This is why CO₂ incidents don’t look dramatic at first — until people and animals collapse without understanding why.
Pressure Changes Everything
High-pressure CO₂ pipelines operate at conditions far beyond typical gas distribution systems. If a rupture occurs:
• The pressure drop causes rapid cooling
• Steel can become brittle
• Valves and seals experience extreme stress
• The escaping CO₂ can form a dense, ground-hugging cloud
This is not hypothetical. It is well documented in industrial safety literature and past incidents.
“It’s Not Pure CO₂” Is the Bit People Skip Over
Captured CO₂ from industry is rarely pristine. It can contain trace contaminants — hydrogen sulphide, sulphur compounds, nitrogen oxides, heavy metals — depending on the source and the level of cleaning applied.
Under pressure, in the presence of moisture, CO₂ forms carbonic acid. Add impurities, and you increase the risk of internal corrosion, material fatigue, and long-term degradation of the pipe.
In other words: the pipe doesn’t just contain risk — it is chemically worked on from the inside, for decades.
Small Leaks, Long Timeframes
Unlike an oil spill or gas explosion, CO₂ leakage does not announce itself with flames or slicks.
The real concern is small, chronic leaks — the kind that are hard to detect, easy to downplay, and inconvenient to admit.
Over years, these can mean:
• Soil acidification
• Aquifer contamination
• Invisible risk zones along pipeline corridors
• Long-term monitoring obligations that quietly outlive the companies that built them
So Why the Extra Scrutiny?
CO₂ pipelines combine:
• Extremely high pressure
• Unusual physical behaviour
• Asphyxiation risk rather than explosion risk
• Chemical reactivity
• Very long operational lifetimes
That combination is not comparable to ordinary gas infrastructure, no matter how often it’s presented that way.
Asking harder questions about routing, materials, monitoring, emergency planning, and long-term liability isn’t alarmism. It’s basic due diligence — especially when these pipelines cross communities, farmland, or environmentally sensitive areas.
In short:
This isn’t a normal pipe carrying a normal gas.
And pretending otherwise is the most dangerous shortcut of all.
And now for the boring bits,
the evidence for what im saying
Small Leaks & Long-Term Risks
• Research indicates CO₂ pipelines may be more susceptible to small ruptures than oil/gas pipelines, meaning CO₂ could leak for longer periods without detection
• Chronic leakage risks include: soil acidification, aquifer contamination (when dissolved in water forms carbonic acid), and vegetation degradation
• 76 accidental releases from CO₂ pipelines since 2010, with 54,000 barrels released (mostly Denbury/ExxonMobil)
Regulatory Gap — The “Why Now” Factor
This strengthens your conclusion about extra scrutiny:
• PHMSA regulations for CO₂ pipelines haven’t been significantly updated since 1991
• Proposed new rules (January 2024) would require planning for gas releases harming people within 2 miles of a pipeline—acknowledging the unique threat radius
• Bill Caram, Pipeline Safety Trust: “PHMSA finally recognizes that the threats from CO₂ pipelines are different from oil and natural gas pipelines, which can spill, burn or explode, but don’t usually imperil people miles away”
The Satartia Incident (2020) — Primary Evidence
Reference: Earth Justice / Environmental Integrity Project
URL: https://earthjustice.org/press/2025/new-report-air-products-carbon-dioxide-pipeline-is-dangerously-close-to-a-school-and-neighborhood
Evidence: 45 people hospitalized, ~200 evacuated; cars stalled due to oxygen displacement; unconscious people reported over a mile from the site
Reference: Verite News / Louisiana Illuminator
URL: https://lailluminator.com/2024/05/01/carbon-dioxide-leak/
Evidence: Detailed account of the 2020 Satartia rupture: “emergency responders found people passed out or disoriented and struggling to breathe”
Reference: PHMSA Notice of Proposed Rulemaking (2025)
URL: https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2025-01/PHMSA%20Notice%20of%20Proposed%20Rulemaking%20for%20CO2%20Pipelines%20-%202137-AF60.pdf
Evidence: Official acknowledgment: “Over the 10-year period from 2010 to 2021, 66 accidents on pipelines transporting supercritical-phase carbon dioxide have been reported to PHMSA”
CO₂ Is Not “Just Another Gas” — Supercritical State
Reference: MDPI Energies (Peer-reviewed)
URL: https://www.mdpi.com/1996-1073/17/16/3943
Evidence: “For the supercritical phase, the typical operating pressure range of the pipeline is 8–15 MPa at temperatures of 308.2–323.2 K… density comparable to the liquid state and viscosity and compressibility comparable to the density of the gas phase”
Reference: PMC / National Center for Biotechnology Information
URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC8264839/
Evidence: Technical analysis of supercritical CO₂ decompression behavior and fracture propagation velocity
Ground-Hugging Behavior & Asphyxiation Risk
Reference: Brodies LLP (UK Health & Safety Analysis)
URL: https://brodies.com/insights/health-and-safety/the-health-and-safety-landscape-for-carbon-capture-and-storage/
Evidence: “In higher concentrations it can cause confusion, dizziness and a loss of consciousness, and in confined spaces it can displace oxygen resulting in asphyxiation… Even a minor leak could have catastrophic consequences”
Reference: NIOSH Pocket Guide to Chemical Hazards (CDC)
URL: https://www.cdc.gov/niosh/npg/npgd0103.html
Evidence: IDLH (Immediately Dangerous to Life or Health) concentration: 40,000 ppm; symptoms include headache, dizziness, dyspnea, coma, asphyxia
Reference: MDPI Energies
URL: https://www.mdpi.com/1996-1073/17/16/3943
Evidence: CO₂ is 1.5× heavier than air; dispersion modeling shows ground-hugging behavior at concentrations of 30,000 ppm
Ductile Fracture / “Unzipping” Phenomenon
Reference: SDEA Solutions (Pipeline Risk Assessment)
URL: https://sdeasolutions.com/co2-dense-phase-pipelines/
Evidence: “Dynamic ductile fracture” photos and explanation of fracture propagation in CO₂ pipelines; decompression speed effects unique to CO₂
Reference: IChemE Hazards Symposium
URL: https://www.icheme.org/media/11822/hazards-26-poster-17-fracture-propagation-in-dense-phase-co2-pipelines-from-an-operator-s-perspective.pdf
Evidence: National Grid full-scale fracture propagation tests showing “running ductile fracture” at ~100 m/s in dense phase CO₂

Impurity & Corrosion Chemistry
Reference: ScienceDirect (Peer-reviewed)
URL: https://www.sciencedirect.com/topics/engineering/carbon-dioxide-corrosion
Evidence: “When carbon dioxide is dissolved into water, carbonic acid is formed… CO₂ corrosion of carbon and alloy steels is called ‘sweet corrosion’… In the presence of water, carbon dioxide can form carbonic acid, which reduces the pH of the fluid and causes corrosion” 
Reference: PHMSA NPRM (2025)
URL: https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2025-01/PHMSA%20Notice%20of%20Proposed%20Rulemaking%20for%20CO2%20Pipelines%20-%202137-AF60.pdf
Evidence: “deleterious constituents can include hydrogen sulfide and water, among others… operators to establish a monitoring and mitigation program to address corrosion-affecting constituents in the product stream” 
Reference: PMC / NCBI (Corrosion Science)
URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC12566176/
Evidence: “Advances in Synergistic Corrosion Mechanisms of and Management Strategies for Impurity Gases During Supercritical CO₂ Pipeline Transportation” 
Small Leaks & Incident Statistics
Reference: Grist / Verite News
URL: https://grist.org/regulation/efforts-were-underway-to-prevent-co2-pipeline-leaks-the-trump-administration-quietly-derailed-them/
Evidence: “Accidental releases have occurred from CO₂ pipelines 76 times since 2010… Of the more than 67,000 barrels of CO₂ released over the past 15 years, the vast majority — about 54,000 barrels — came from pipelines owned by Exxon Mobil subsidiary Denbury Inc.”
Reference: Oil & Gas Watch
URL: https://news.oilandgas