Gas detection
But one of the less glamorous findings from projects in Mississippi, particularly around Jackson Dome and the Kemper County CCS demonstration, is that scale is meaningless if the carbon stream isn’t pure.
Monitoring professionals know that data gaps rarely stay hidden for long.
Mississippi showed how impurities in captured CO₂ can corrode pipelines, interfere with injection wells, and even undermine the geological stability of the reservoirs meant to keep carbon locked away for centuries.
If anything, the purity problem revealed that the technical success of CCS is not just about how much CO₂ you store, but what kind of CO₂ you are storing.
Captured CO₂ rarely comes out of a flue stack in a usable state. Alongside carbon, streams can carry oxygen, nitrogen, argon, carbon monoxide, sulphur oxides (SOₓ), nitrogen oxides (NOₓ), and water vapour.
Mississippi’s projects illustrated the consequences of ignoring these minor contaminants.
Water is particularly insidious. Even a few hundred parts per million can combine with CO₂ under pressure to form carbonic acid, a substance with a corrosivity comparable to diluted sulphuric acid.
When sulphur compounds are present as well, pitting and cracking in steel pipelines can occur rapidly.
Operators in Mississippi reported significant challenges in ensuring that captured CO₂ was sufficiently dried and purified before transport, not least because purification technologies add complexity and continuous monitoring requirements.
Without vigilant impurity control, pipelines that are supposed to last decades may fail in years. For an industry already under scrutiny, this risk translates into financial liability.
If pipeline corrosion is a surface-level concern, the subsurface adds another, more complex challenge.
Mississippi is home to Jackson Dome, a natural CO₂ reservoir that has long supplied food and chemical industries.
When captured CO₂ was considered for injection into nearby formations, operators and geologists discovered that impurities had unpredictable effects underground.
Trace oxygen can alter redox balances in brines, mobilising metals or clogging pore spaces with precipitated minerals.
Sulphur species can react with carbonate rocks, weakening structural integrity or altering flow paths.
The ability of a reservoir to physically and chemically trap CO₂ over centuries can be compromised if impurities interfere with solubility or mineralisation pathways.
In practice, this meant that some formations that looked promising on paper for injection showed poorer performance when impurity-laden streams were introduced.
That lesson has since reverberated through the CCS community: not all reservoirs are equal, and not all CO₂ behaves the same way underground.
This is where monitoring professionals become central. The Mississippi experience highlighted three areas where instrumentation and data collection need to be elevated:
For pipeline purity assurance, inline spectroscopy, chromatographs and high-sensitivity moisture detectors are critical.
These aren’t simply quality checks, but safety systems.
Real-time, high-frequency data on CO₂ purity prevents corrosive events from escalating and provides early warning of contamination upstream.
Standard CCS monitoring has focused on seismic surveys, well pressure, and surface leakage detection.
Mississippi suggests we need a closer watch on geochemical signals: sensors that can track shifts in brine composition, pH, and mineral precipitation.
Fibre-optic sensing, coupled with periodic fluid sampling, may become essential to verify long-term storage integrity.
Most importantly, monitoring should not be siloed.
Purity data at the capture site, corrosion data along pipelines, and reservoir chemistry data must be integrated into a common framework.
This would allow operators to anticipate how upstream purity fluctuations might translate into downstream storage performance.
Why does a regional project in Mississippi matter globally? Because it challenges assumptions baked into CCS policy frameworks.
Many national strategies, from the EU to Asia-Pacific, focus on tonnes captured and injected as the main metric of success.
Yet if impurities undermine infrastructure or storage permanence, those numbers are misleading.
The Mississippi case suggests that future CCS regulations may need to:
Set minimum purity standards for transported and injected CO₂ streams.
Mandate continuous purity monitoring along pipelines, not just batch testing at capture points.
Require geochemical modelling that accounts for impurities, rather than assuming pure CO₂ behaviour in reservoirs.
For instrumentation suppliers and monitoring professionals, this shift could mean new markets.
Purity sensors, corrosion monitors, and geochemical analytics may become as critical as flow meters or seismic arrays in the CCS toolkit.
Another reason the Mississippi findings matter: CCS feedstocks are diversifying.
Early projects often drew from relatively “clean” sources such as natural gas processing, where CO₂ streams are already high-purity.
But as CCS expands to cement plants, steelworks, and waste-to-energy facilities, the impurity problem grows. These streams are more complex, variable, and harder to clean.
That means monitoring must keep pace.
Capture facilities cannot rely on one-off certification; they need continuous data to prove that what they are sending down the pipeline is safe and compliant.
The Mississippi projects may ultimately be remembered less for how much CO₂ they stored than for how much they revealed about the bottlenecks of purity.
For CCS to be credible, pipelines must not corrode, reservoirs must not destabilise, and carbon must remain underground for centuries.
All three conditions depend on monitoring the chemical integrity of CO₂ streams.
In short: if you can’t measure the purity, you can’t guarantee the permanence.
As CCS scales up, lessons from Mississippi could shape global practice.
North Sea operators are already considering stricter specifications for incoming CO₂, while projects in the Middle East are investigating advanced drying and purification systems.
Asia-Pacific nations, eager to adopt CCS at pace, face the risk of repeating Mississippi’s challenges if they treat purity as an afterthought.
For monitoring professionals, this creates a responsibility and an opportunity.
The responsibility is to anticipate how impurities affect both infrastructure and geology, not just emissions accounting.
The opportunity is to supply the tools and frameworks that make purity monitoring a standard pillar of CCS.
Because if Mississippi taught us anything, it’s this: in carbon capture, the difference between success and failure may lie in the contaminants no one sees until it’s too late.
IET 36.2 Mar/Apr 2026
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