Editing CO2 Shipping (section)

=== Indicative Specification Ranges ===
Published shipping specifications vary by project, but early CCS projects have referenced stringent ppm-level limits for several contaminants. One widely cited comparison shows (i) a Northern Lights shipping specification (ppm mol) alongside (ii) EU recommendations used for broader transport discussions.<ref name="ZEPShippingSpecs">ZEP/CCSA (2022)</ref>

{| class="wikitable"
|+ Indicative impurity specifications for CO₂ shipping (examples from published sources). ''NS: Not Specified''
! Component !! Northern Lights example (ppm mol) !! EU recommendation example !! Notes
|-
| CO2 || NS || >99.7% by volume || Total purity basis differs across documents and contracts.
|-
| H2O || ≤30 || <50 ppm || Water control is central for corrosion/ice risk.
|-
| O2 || ≤10 || NS || Often tightened for corrosion control.
|-
| H2S || ≤9 || <200 ppm || Toxicity and acid formation risks.
|-
| SOx || ≤10 || NS || Acid formation and materials risk.
|-
| NOx || ≤10 || NS || Acid formation and materials risk.
|-
| CO || ≤100 || <2000 ppm || Typically managed for safety/compatibility and monitoring.
|-
| H2 || ≤50 || <0.3% by volume || Non-condensable; affects phase behaviour/pressure.
|-
| NH3 || ≤10 || NS || Capture-process dependent.
|-
| Amine (total) || ≤10 || NS || Capture-process dependent.
|-
| Methane (CH<sub>4</sub>) || NS || <0.3% by volume || Non-condensable; affects phase behaviour/pressure.
|-
| Argon (Ar) || NS || <0.3% by volume || Non-condensable; affects phase behaviour/pressure.
|-
| Formaldehyde || ≤20 || Not defined || Trace contaminant; process dependent.
|-
| Acetaldehyde || ≤20 || Not defined || Trace contaminant; process dependent.
|-
| Mercury (Hg) || ≤0.03 || Not defined || Materials/health considerations.
|-
| Cadmium (Cd) / Titanium (Ti) (sum) || ≤0.03 || Not defined || Trace metals; contract-specific.
|}
<ref name="ZEPShippingSpecs"/>

''Note:'' Specifications must be developed on a whole-chain basis (capture → conditioning → terminal → ship → receiving terminal → storage), because temperature/pressure selection and impurity limits are coupled; lower-temperature shipping can require more stringent impurity control.<ref name="ZEPWholeChain">ZEP/CCSA (2022)</ref>