CCUS - Process risks and safety technologies

No. Oxygen monitoring alone will not protect your personnel, because CO₂ becomes dangerous before oxygen levels drop far enough to trigger an alarm. 

At high concentrations, the cause of harm is not hypoxia but CO₂ intoxication. Effects can begin at around 3 % by volume, and above 5 % CO₂ acts as a toxin, causing hypercapnia with headache, confusion, and unconsciousness, regardless of how much oxygen is present. An O₂ sensor cannot see this coming: CO₂ can reach hazardous levels while oxygen readings still look acceptable, and by the time the O₂ alarm sounds, exposure has already occurred. 

For reliable measurement, non-dispersive infrared (NDIR) sensors are the right technology. They cover ppm to percent by volume ranges and remain drift-free in industrial conditions, while electrochemical sensors are unsuitable at these concentrations. Fixed transmitters such as the Dräger Polytron 8720 IR integrate directly into plant control systems. 

The answer is not either-or: measure both O₂ and CO₂, and place CO₂ detection where the gas actually collects. 

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Because the danger is not only the gas. In CCUS, CO₂ is handled close to or above its critical pressure of 73.82 bar and critical temperature of 31.04 °C, where it behaves like a liquid. A sudden loss of pressure then triggers a chain of physical effects that a standard gas leak does not produce. 

On release, the CO₂ expands and cools rapidly (the Joule-Thomson effect). This can cause: 

• Explosive decompression with thrown debris and damaged equipment.

• Dry ice formation and cryogenic injury, including to the respiratory tract if the cloud is inhaled. 

• Brittle fracture of pipeline and equipment materials at low temperature. 

• A cold, dense cloud that hugs the ground, displaces oxygen and spreads far from the release point.

Regulators treat this as a major accident hazard: dense-phase CO₂ released at or above critical pressure is recognised as capable of causing serious harm, which is why pipeline design, material selection and emergency planning are assessed accordingly.  

Plan for the physical event, not just the gas cloud: detection at low level, escape equipment within reach, and emergency procedures that account for cold and debris as well as asphyxiation.

More than you might expect – and the mix depends entirely on the process stage and the feedstock. 

In amine-based capture, the critical substances alongside CO₂ are amine vapours such as monoethanolamine (MEA), which is corrosive and causes skin burns, eye damage and respiratory irritation. Solvent degradation adds volatile organic compounds, nitrosamines and nitramines, some of them toxic or potentially carcinogenic at low concentrations. 

From upstream processes you may also see SO₂, NOx, H₂S, CO and oxygen deficiency. In utilisation, flammable and toxic reaction partners take over: hydrogen, carbon monoxide, methanol vapours or ammonia, depending on the conversion route. At injection wells in depleted fields, H₂S can migrate back through the well. 

Sensor technology has to match the substance. Infrared is the right choice for CO₂; for toxic gases at ppm level, electrochemical sensors are the correct technology. Multi-gas devices such as the Dräger X-am 5600 measure up to six substances simultaneously for personal monitoring and leak searching, while the fixed Dräger Polytron series scales to plant level with data logging for incident reconstruction and audits. 

Do not plan gas detection around CO₂ alone. Base the sensor mix on your capture technology and feedstock, and reassess it whenever either changes. 

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Put them low. CO₂ is around 60 % heavier than air, so it sinks, flows along the ground and collects in the lowest available space, which is rarely where a detector is easiest to mount. 

Prioritise the places where CO₂ gathers: beneath pipelines, in bunds, pits and trenches, in compressor houses, around wellheads and well cellars, at loading points and in confined spaces. CO₂ can remain there long after it has dispersed at head height. 

Positions should follow a risk assessment and scenario-based gas mapping study rather than plant layout convenience, with redundant coverage in high-risk areas and integration into central alarm and ventilation systems. Point IR detectors such as the Dräger PIR 7200, or the Polytron 8720 IR transmitter built around the same sensor, cover these fixed points from ppm to percent by volume. 

Where exposure is not yet fully understood, temporary measurement can build the evidence base first. The wireless Dräger X-node records CO₂ continuously for analysis, but is designed for non-hazardous areas, so zone classification determines where it can be used. 

Let gas mapping decide the positions, not the plant layout. 

Only equipment with an independent air supply is appropriate. Air-purifying respirators are not suitable: their filters cannot remove CO₂ and offer no protection in an oxygen-deficient atmosphere. 

The choice depends on expected exposure duration and the distance to safe breathing air. For planned work in areas where high CO₂ concentrations are possible, self-contained breathing apparatus covers extended use. For evacuation, compact emergency escape devices such as the Dräger Saver PP or PAS Colt are appropriate. Where H₂S may be present, for example at injection wells in depleted fields, the device must be rated for it. Regular fit-testing and scenario drills determine whether the equipment works when it matters. 

Emergency response requires immediate evacuation and alarm activation, emergency ventilation, and designated safe zones with clean breathing air. Because CO₂ collects at low level, evacuation routes should lead upwards and upwind, and personnel must be kept out of pits, cellars and trenches where concentrations persist. Staff should be trained to recognise CO₂ exposure symptoms and follow clear reporting lines, with local emergency services briefed in advance as dense-phase releases add cold and debris to the asphyxiation hazard.  

Up-to-date equipment, including mobile detectors like the Dräger Pac 8000, and escape devices, provide layered protection. Incident reporting and analysis through digital safety management platforms support ongoing improvement and compliance.  

Rehearse the scenario, not just the alarm. 

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Three frameworks overlap, and none of them targets CO₂ directly. 

The CCS Directive (2009/31/EC) governs geological storage: site permitting, monitoring, closure and the transfer of responsibility to the competent authority. After closure the operator remains responsible for monitoring, reporting and corrective measures until that transfer, which cannot occur earlier than 20 years – several member states require 30 or 40 years or decide case by case. 

Seveso III (2012/18/EU) applies where dangerous substances exceed threshold quantities – CO₂ itself is not one of them, but amine-based capture solvents or co-located hydrogen production can bring a site into scope. 

ATEX applies wherever flammable process gases are handled, which is typical in utilisation. 

National implementation varies, and some member states go beyond the directives. Check scope per asset and per member state, not per site.

More often than most maintenance plans assume. As a baseline: 

• Fixed systems: functional test typically every 4 months; calibration according to manufacturer recommendations and industry standards – at Dräger typically every 12 months. 

• Portable detectors: bump test daily and a visual inspection before each use. 

• High-risk applications: shorter intervals, and a functional check before every critical operation. 

Intervals are only half of it. Maintenance logs and scheduled servicing are required for compliance and auditability, and prompt repair or sensor replacement prevents a device from being nominally present but functionally 'blind'. In CCUS this matters more than in many other applications, because CO₂ gives no warning if a sensor drifts or fails – there is no smell or colour to fall back on. 

Match the interval to the consequence, not to the calendar: unmanned and remote assets need a documented schedule precisely because no one is there to notice a fault. 

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They close the distance. Much of a CCUS chain runs remote or unmanned – transport routes, injection wells, closed storage sites – and monitoring obligations continue for decades. Without connected data, someone has to be physically present to know the status. 

Cloud platforms such as Dräger Gas Detection Connect link sensor data, alarm notifications and maintenance logs into one view, accessible across plant areas and sites. Three things follow from that: 

• Lone working becomes visible. Alarms from a personal detector reach someone who can act, instead of staying with the person in trouble. 

• Fleet status instead of spot checks. Which device is due for calibration, which sensor is drifting, which alarm repeats at the same location. 

• Documentation without reconstruction. Trend data and logs support audits and incident investigation because the record already exists. 

Start with the assets no one visits daily: that is where connected monitoring pays back fastest. 

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