Editing CO2 Pipelines

'''Carbon dioxide pipelines''' are pipelines used to transport carbon dioxide (CO<sub>2</sub>) typically in a dense (highly compressed) or supercritical state—from capture or production sites to end uses such as [[Enhanced oil recovery|CO2-EOR]], [[Carbon Capture, Utilisation, and Storage|geological storage]], or utilisation. CO<sub>2</sub> pipeline transport is generally most economic for large, consistent CO<sub>2</sub> flows over low-to-medium distances where economies of scale apply.<ref name="VITO2025">UPDATE</ref>

== Overview ==
CO<sub>2</sub> pipelines are a technologically transport mode for high-volume CO<sub>2</sub> movement. As of 2025, an estimated ~11,500 km of CO2 pipelines are operational worldwide, with ~9,000 km located in the United States and Canada.<ref> UPDATE</ref> Historically, most long-distance CO<sub>2</sub> pipelines have supported CO<sub>2</sub>-EOR in North America; dedicated CCS networks (including offshore trunklines) are expanding in Europe and other regions as capture clusters and storage hubs mature.<ref>UPDATE</ref>

== History ==
The first large-scale CO<sub>2</sub> pipeline was the Canyon Reef Carriers pipeline (constructed in 1972; ~225 km), developed to supply CO<sub>2</sub> for EOR operations and still operating.<ref>UPDATE</ref> Since then, pipeline networks have expanded, primarily in the U.S., to connect natural CO<sub>2</sub> sources from subsurface reservoirs and anthropogenic CO<sub>2</sub> supplies from industrial facilities to oilfields, and more recently to connect captured CO<sub>2</sub> sources to dedicated storage sites.<ref>UPDATE</ref>

== Physical Properties and Phases ==

''Main article [[Properties of Carbon Dioxide]]''

CO<sub>2</sub> is generally transported in dense phase (compressed fluid) or supercritical conditions to increase density and reduce volumetric flow, improving transport economics. CO<sub>2</sub> becomes supercritical above its critical point (critical pressure ~7.38 MPa and critical temperature ~31.1 °C).<ref name="NISTcritical">CITE NIST + a PT diagram</ref>

>>INSERT P-T Phase Diagram

Commercial CO<sub>2</sub> pipelines operate across a broad pressure range; one 2025 technical summary reports typical operating pressures of ~83–152 bar, with peak pressures up to ~172–193 bar in some systems (site- and design-dependent).<ref> Find the VITO reference</ref> Maintaining pressure above minimum operating limits helps avoid two-phase flow and associated operability and integrity issues.

Gas phase CO<sub>2</sub> is also completed in certain circumstances, however due to the higher pressure loss as a result of the different density and viscosity, these pipelines are limited to large diameter and short distances to be cost effective <ref>CITE</ref>

===Two Phase Flow===

== System Design and Operation ==
Typical CO<sub>2</sub> pipeline systems comprise:
* Compression and/or pumping (compressors for gas compression; pumps often used once in dense/supercritical phase, subject to design choices).
* Dehydration and Conditioning to control corrosion/flow assurance risks (see [[#CO2 stream quality and impurities|CO2 stream quality and impurities]]).
* Block valves and pressure/flow control stations for sectional isolation and operational control.
* Booster stations where required by hydraulics to account for pressure loss

Key design considerations include:
* Route selection and siting (population density, high consequence areas, topography, third-party interference, environmental constraints).
* Material selection and fracture control (running ductile fracture control can be critical in dense-phase CO<sub>2</sub> service; decompression behavior differs from typical natural gas).
* Corrosion management (strongly influenced by free water and acid-forming impurities such as SO<sub>2</sub>/NO<sub>2</sub>).
* Flow assurance (phase management; impurity impacts; hydrates/solids such as dry ice during rapid depressurization events).

== CO<sub>2</sub> Stream quality and Impurities ==
There is no single, universally applied CO<sub>2</sub> composition specification for pipeline transport. Multiple guidance efforts (e.g., ENCAP, DYNAMIS, CO2PIPETRANS) have produced recommended limits, but practice remains largely '''project-specific''' and depends on source streams, downstream requirements, and integrity risk tolerance.

=== Typical impurity themes ===
Impurities of interest commonly include: H<sub>2</sub>O, H<sub>2</sub>S, SOx, NOx, O<sub>2</sub>, N<sub>2</sub>, CH4 and other hydrocarbons, CO, H<sub>2</sub>, Ar, and trace species (e.g., NH<sub>3</sub>, particulates). Impurities can affect:
* Internal corrosion (notably with water + acid-formers like SO<sub>2</sub>/NO<sub>2</sub>).
* Phase behavior and minimum pressure needed to stay in dense phase.
* Health and safety impacts in leak scenarios (e.g., toxic impurities such as H<sub>2</sub>S).

=== Indicative Specification Ranges (illustrative) ===
The table below summarises example values discussed in major specification work; these are not universal requirements and should be treated as indicative only.

{| class="wikitable"
! Parameter / component !! Example indicative guidance (illustrative) !! Notes
|-
| CO<sub>2</sub> content || >95–96% vol% || Often driven by dense-phase/operability and commercial product requirements.<ref>Need a summary piece</ref>
|-
| Water (H<sub>2</sub>O) || Typically tens to hundreds of ppmv || Projects and operators vary; water limits depend on other impurities and corrosion risk (SO2/NO2 sensitivity).<ref>Need a summary piece</ref>
|-
| H<sub>2</sub>S || Typically ppmv range || Driven by health/safety and materials compatibility; some EOR systems tolerate higher H<sub>2</sub>S depending on reservoir context.<ref>Need a summary piece</ref>
|-
| Non-condensables ( N<sub>2</sub>, O<sub>2</sub>, Ar, H<sub>2</sub>) || capped as a group, generally less than 5 vol% || Impacts phase envelope and compression/pumping needs.<ref>Need a summary piece</ref>
|-
| SOx / NOx || typically capped (ppmv range) || Acid-formers can materially increase corrosion risk when water is present.<ref>Need a summary piece</ref>
|}

== Safety and Risk Management ==
CO<sub>2</sub> is non-flammable, but can pose acute hazards in releases due to:
* '''Asphyxiation risk''' (CO<sub>2</sub> is heavier than air and can accumulate in low-lying areas).
* '''Visibility and dispersion''' (cold dense clouds; potential for dry ice formation during rapid decompression).
* '''Impurity hazards''' where present (e.g., H<sub>2</sub>S in certain CO<sub>2</sub>-EOR supply systems).<ref> CITE</ref>

>> INSERT SIGTTO Chart
+ 
Insert discussion on TWA/STEL

Risk management typically includes routing and class location considerations, isolation/valving strategies, leak detection and SCADA monitoring, emergency response planning and coordination with local authorities, and public communication for communities along the right-of-way.

=== Notable Incidents ===
''Main Article [[CO2 Pipeline Safety]]''

In February 2020, a CO<sub>2</sub> pipeline rupture near Satartia, Mississippi (U.S) prompted evacuations and hospitalisations reported in contemporaneous coverage, and was subsequently subject to a PHMSA failure investigation process.<ref>CITE startia report</ref><ref> Cite GCCSI report</ref>
Discuss how any why

CITE GPI meta analysis of failure rates

== Notable CO<sub>2</sub> pipeline systems ==
The table below lists selected CO<sub>2</sub> pipelines and CO<sub>2</sub> transport trunklines. Many North American systems were developed for CO<sub>2</sub>-EOR; newer European systems are focused on CO<sub>2</sub> storage hubs.

'''CONFIRM OPERATORS and CAPACITY ARE STILL ACCURATE PER PHMSA, and add network'''

{| class="wikitable sortable"
! Pipeline / System !! Country/Region !! Operator / Developer !! Length !! Diameter !! Capacity (indicative) !! Primary Service !! Notes
|-
| Canyon Reef Carriers (CRC) || USA (TX) || Kinder Morgan || 139 mi / 225 km <ref>CITE 2015 DOE</ref> || 16 in <ref>CITE 2015 DOE</ref> || 220 MMcfd (est.)<ref>CITE 2015 DOE</ref> || EOR || Often cited as first large-scale CO2 pipeline (1972).<ref> name="VITO2025" </ref>
|-
| Cortez || USA (TX, CO source region) || Kinder Morgan || 502 mi / 808 km <ref>CITE 2015 DOE</ref> || 30 in <ref>CITE 2015 DOE</ref> || 1,300 MMcfd (est.) <ref>CITE 2015 DOE</ref> || EOR || Major trunkline supplying [[Permian EOR]].
|-
| Bravo || USA (NM/TX region) || Occidental Petroleum, through the Bravo Pipeline Company || 218 mi / 351 km <ref>CITE 2015 DOE</ref> || 20 in <ref>CITE 2015 DOE</ref> || 380 MMcfd (est.) <ref>CITE 2015 DOE</ref> || EOR || ~
|-
| Delta || USA (MS, LA) || ExxonMobil || 108 mi / 174 km <ref>CITE 2015 DOE</ref> || 24 in <ref>CITE 2015 DOE</ref> || 590 MMcfd (est.)<ref>CITE 2015 DOE</ref> || EOR || [[Gulf Coast Network|Gulf Coast CO<sub>2</sub> network]] segment.
|-
| Green Line || USA (LA, TX) || ExxonMobil || 314 mi / 505 km <ref>CITE 2015 DOE</ref> || 24 in<ref>CITE 2015 DOE</ref> || 930 MMcfd (est.)<ref>CITE 2015 DOE</ref> || EOR || Large-scale CO2 trunkline.
|-
| Greencore || USA (WY, MT) || ExxonMobil || 230 mi / 370 km <ref>CITE 2015 DOE</ref> || 22 in<ref>CITE 2015 DOE</ref> || 720 MMcfd (est.)<ref>CITE 2015 DOE</ref> || EOR ||  [[Rocky Mountain Network|Rocky Mountain region]] system.
|-
| Northeast Jackson Dome (NEJD) || USA (MS, LA) || ExxonMobil || 183 mi / 295 km<ref>CITE 2015 DOE</ref> || 20 in<ref>CITE 2015 DOE</ref> || 360 MMcfd (est.)<ref>CITE 2015 DOE</ref> || EOR || ~
|-
| Sheep Mountain || USA (TX) || Oxy Permian || 408 mi / 657 km <ref>CITE 2015 DOE</ref> || 24 in<ref>CITE 2015 DOE</ref> || 590 MMcfd (est.)<ref>CITE 2015 DOE</ref> || EOR || Permian Basin CO2 transport.
|-
| Dakota Gasification (Souris Valley) / Weyburn || USA/Canada (ND–SK) || Dakota Gasification || 204 mi / 328 km <ref>CITE 2015 DOE</ref> || 14 in<ref>CITE 2015 DOE</ref> || 130 MMcfd (est.)<ref>CITE 2015 DOE</ref> || EOR / storage || Supply noted for relatively high H2S in some references.
|-
| [[Alberta Carbon Trunk Line]] (ACTL) || Canada (AB) || Wolf Carbon Solutions / partners || ~240 km <ref>Cite knowledge sharing</ref> || (varies by segment) || up to ~14.6 MtCO2/yr (reported)  <ref>Cite knowledge sharing</ref>|| EOR || Major CO<sub>2</sub> trunkline in Alberta’s Industrial Heartland to central Alberta.
|-
| [[Snøhvit]] || Norway (Barents Sea) || (associated with Snøhvit CCS) || ~153 km seabed pipeline<ref>Cite</ref> || (offshore) || (project-specific) || CCS (storage) || Offshore CO2 transport to injection wells (operating since 2008)
|-
| [[Northern Lights]] CO<sub>2</sub> pipeline (Phase 1) || Norway (North Sea) || Northern Lights JV || ~100 km subsea pipeline (reported)<ref>Cite </ref> || (offshore) || ~5 MtCO<sub>2</sub>/yr (Phase 1 as 1.5 MtCO<sub>2</sub>/yr, reported<ref>Cite </ref>) || CCS (storage hub) || CO<sub>2</sub> shipped to onshore terminal then sent offshore by pipeline to storage reservoir.<ref>Cite </ref>
|}


== See also ==
* [[Carbon capture and storage]]
* [[Carbon dioxide removal]]
* [[Enhanced oil recovery]]
* [[CO2 pipeline specifications]]

== References ==
<references />

[[Category:Pipelines]]