CO2 Transport Pipelines
Getting the stream from the emitter to the storage site - a linear construction project that crosses farmland, roads, rivers, towns and usually a stretch of seabed, built by a spread that moves every day.
Last updated 2026-09-06
Typical duration
Consents and land access commonly run for two to four years; onshore construction of a long route takes one to two seasons once the spread is moving, and offshore lay is measured in weeks of vessel time inside a much longer campaign.
What is CO2 Transport Pipelines?
Once the stream is compressed it has to travel, and for anything above modest volumes that means a pipeline. This is a different kind of construction from everything before it. The capture plant is a single congested site; the pipeline is a linear project that might run tens or hundreds of kilometres, and the working front moves along it every day. Onshore, the operation is a spread - a chain of gangs each doing one job, strung out along the route, following each other in sequence. Offshore, it is a marine campaign built around a lay vessel and a weather window. The two halves are usually delivered by different contractors with different disciplines, meeting at a landfall.
The fluid drives a lot of the engineering. Dense-phase CO2 is heavy for its volume, so a pipe of ordinary diameter moves a very large mass, which is the whole reason the transport economics work. But it is also a fluid that changes behaviour sharply if the pressure drops, and it is aggressive towards carbon steel if water is present, which is why the drying done upstream is a condition of entry rather than a nicety. Wall thickness, material selection, valve spacing, venting arrangements and the safety case for the route are all matters for the designer, worked through with the regulator and the pipeline operator. Construction's job is to build precisely what that design says and to prove that it did.
The rest of the difficulty is not technical at all - it is land, consent and people. A pipeline route crosses hundreds of ownerships, dozens of other utilities, protected habitats, archaeology, watercourses, roads and railways, and often the edges of communities who never asked for it. Every crossing needs a separate agreement with a separate party. Every landowner needs access terms, a working width, a reinstatement standard and someone who answers the phone. Consents, land access and third-party agreements routinely take longer than the construction and they are the reason pipeline projects are measured in years rather than seasons.
Compare the methods at a glance
When and why is CO2 Transport Pipelines used?
The pipeline is the link that makes the rest of the chain worth building, and its programme rarely matches anybody else's. It has to be complete and proved before the capture plant can do anything with what it captures, but its own critical path runs through consents and land access rather than through construction, so it usually starts long before the capture plant and finishes on a schedule of its own. On cluster schemes the pipeline is normally built by a separate transport and storage operator serving several emitters, which means the interfaces are commercial as well as physical - an entry specification, a metering point, an availability commitment and an agreement about who is responsible for what when something goes wrong. Sequencing along the route is dictated by seasons and by other people's calendars. Farmland access is negotiated around cropping and harvest. Watercourse crossings sit inside ecological windows. Road and rail crossings are booked with the relevant authority months ahead and often happen at night. Offshore lay is booked against vessel availability years ahead and constrained by weather. Miss any of those windows and the wait is a season, not a week. There is also a straightforward reason to build a pipeline well rather than quickly: it will be buried, invisible and expected to work for decades, and every defect built into it is a defect somebody has to dig up. The welding, inspection, coating and testing regime exists because repairing a buried pipeline is expensive, disruptive and, if it happens after the system is in service, requires taking the whole chain down. The economics of the entire scheme assume the pipe just runs.
Types of CO2 Transport Pipelines
Explore each method in depth - benefits, limitations, plant and quality control on its own page.
Onshore buried pipeline
Built by a spread working along an agreed easement: fence, strip, string, weld, inspect, coat, trench, lower in, backfill and reinstate. Highly repetitive and productive once running, but entirely dependent on land access, consents and the weather, and it leaves a permanent obligation to the landowners it crossed.
Explore this methodOffshore subsea pipeline
Laid from a vessel and, depending on water depth and seabed conditions, trenched, buried or protected afterwards. Enormously productive per day and largely invisible once complete, but it depends on vessel availability booked years ahead, on a weather window, and on survey work that has established what is on the seabed before anything is laid.
Explore this methodRepurposed existing pipeline
Re-using a pipeline built for another product. Attractive because the route, the easements and the asset already exist, but only viable after a thorough assessment of the material, the condition, the operating history and the fitness of the line for a different fluid, carried out by the designer and accepted by the regulator. Cleaning and modification work is often substantial.
Explore this methodShipping and marine transport
Used where a pipeline cannot be justified, where the emitter is remote from the storage site, or as an early-phase route before a network exists. Needs a loading terminal, storage tanks, jetty works and a receiving facility, so the marine option trades a linear construction project for two sites and a shipping operation.
Explore this methodBest suited for
- Moving large, steady volumes from an emitter or a cluster to a storage site
- Cluster schemes where one shared trunk line serves several capture plants
- Routes where an existing corridor, easement or repurposable asset already exists
- Projects where decades of operation justify the consent and construction effort a linear scheme demands
CO2 Transport Pipelines: step by step
- 1
Step 1: Route selection, surveys and consents
The route is chosen through a long process of comparing options against constraints - existing development, ground conditions, ecology, archaeology, flood risk, other utilities, landscape, and the safety assessment the designer carries out and discusses with the regulator. Desk study comes first, then walkovers, then geotechnical, topographical, ecological and archaeological survey along the preferred corridor, and offshore a full seabed survey covering bathymetry, seabed conditions, existing cables and pipelines, wrecks and unexploded ordnance. All of it feeds the consent applications, which are the real critical path. Consents are often the longest single activity on the entire capture project, and they are decided by other parties on their own timescales, which is exactly why route work starts years before anybody expects to see a trench.
- 2
Step 2: Land access, working width and third-party agreements
Onshore, the pipeline needs a temporary working width and a permanent easement, and both are negotiated landowner by landowner. Each agreement sets out access, the width, drainage and soil handling, the reinstatement standard, fencing, biosecurity, timing around cropping and stock, and compensation. Alongside them run agreements with every road authority, railway operator, drainage board, navigation authority and utility whose asset the route crosses. This work is unglamorous and it decides the programme. A single unresolved crossing stops a spread that is otherwise working perfectly, so the land team runs well ahead of construction and keeps running for years afterwards, because reinstatement claims and land drainage issues outlive the build by a long way.
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Step 3: Establish the spread - fence, strip and haul
Construction opens the working width and turns it into a temporary road. The easement is fenced, topsoil is stripped and stored separately in the way the agreements require, and access points, haul routes and passing places are formed. Temporary bridges go over watercourses and drains. Soil handling is taken seriously because the reinstatement standard depends on it - topsoil mixed with subsoil is a claim that arrives two harvests later. The spread's support arrangements are set up at the same time: pipe storage yards, welding facilities, compounds, welfare and the logistics chain that will keep a moving front supplied. From this point the operation becomes a production line that has to be fed daily, and any gang that stops holds up everyone behind it.
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Step 4: String, weld and inspect
Pipe joints are delivered to the yards, hauled out along the easement and laid end to end ready for joining. Welding is carried out by qualified welders following procedures the designer has approved, in a sequence that keeps the front moving. Every weld is inspected non-destructively and the results are reviewed by an independent inspector before the joint is accepted; welds that fail are cut out and remade rather than argued about. Each weld is uniquely identified and its records tie back to the pipe joints it connects, so the finished line has a traceable history from mill certificate to field weld. Field joint coating is applied to protect the areas the factory coating does not cover, and the whole line is checked for coating damage before it goes anywhere near a trench.
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Step 5: Trench, lower in, backfill and reinstate
The trench is excavated to the depth and profile the design requires, with the excavation supported or battered as the temporary works design specifies and with dewatering where the water table demands it. The welded string is lowered in using side booms working together, bedded as designed, and backfilled with material that will not damage the coating. Land drains cut during the works are reconnected, subsoil and then topsoil are replaced in the right order, and the surface is reinstated to the standard agreed with the landowner. Marker posts and above-ground furniture go in. Reinstatement is where a pipeline earns or loses its reputation locally, and aftercare - monitoring settlement, drainage and crop performance over following seasons - is part of the job rather than an afterthought.
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Step 6: Cross the difficult things
Roads, railways, rivers, canals and dense service corridors are not crossed by the main spread. They are separate mini-projects, often installed ahead of the spread arriving so that the production line does not stop when it gets there. Trenchless methods - directional drilling, auger boring, micro-tunnelling - put the pipe beneath the obstruction without opening it up, which is what the road authority, the railway operator or the environmental regulator normally insists on. Each crossing has its own design, its own consent, its own launch and reception pits and its own risk assessment, and each one is booked into somebody else's possession or closure calendar. Crossings are also where the ground surprises people, so the site investigation at each one is done properly rather than sampled from the general corridor work.
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Step 7: Offshore lay, trenching, protection and landfall
The offshore section is laid from a vessel that welds and pays out pipe continuously as it moves along the route, working to a pre-lay survey that has confirmed the seabed is clear and prepared. Where the design requires it the line is trenched, buried or covered with rock or mattresses to protect it from fishing gear, anchors and seabed movement. Crossings of existing cables and pipelines are built to agreements with their owners. The landfall - where offshore meets onshore - is the most difficult single point on the route, usually built by drilling out from the shore beneath the beach and the intertidal zone so that the environmentally sensitive area is never opened up, then pulling the offshore line into the completed bore. As-laid surveys record exactly where everything ended up, which matters for the rest of the pipeline's life.
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Step 8: Tie in, test, clean and dry
Sections are joined together, the tie-in welds are inspected to the same regime as everything else, and the line is proved as a whole. Cleaning and gauging tools are run through to remove construction debris and confirm the bore is clear and undamaged. Pressure testing demonstrates the integrity of the completed system under the regime the designer specified and the regulator accepted, and the results are recorded as the permanent evidence of what was built. The line is then dewatered and dried, because leaving water in a pipeline that will carry CO2 undermines every material decision made upstream. Finally the whole asset is documented - weld records, test results, as-built alignment, coating surveys, depth of cover, crossing details - and handed to the pipeline operator, who will rely on that record for inspection and integrity management for decades.
Plant & equipment
- Side boom tractors, excavators and trenching machines working as a moving onshore spread
- Welding equipment, welding habitats and non-destructive testing units
- Pipe haulage, stringing trailers and storage yard handling plant
- Directional drilling, auger boring and micro-tunnelling rigs for crossings
- Pipelay vessels, survey vessels and remotely operated vehicles for the offshore section
- Seabed trenching, rock placement and mattress installation equipment
- Cleaning and gauging tools, plus the launch and receipt facilities to run them
- Pressure testing, dewatering and drying equipment for pre-commissioning
Quality control & testing
- Every weld uniquely identified, non-destructively inspected and independently accepted before burial
- Pipe joint traceability from mill certificate through to final position in the line
- Coating condition surveyed before lowering in, with field joint coatings inspected individually
- Depth of cover, bedding and backfill material verified along the route rather than sampled at the ends
- Pressure test carried out and recorded to the regime the designer specified and the regulator accepted
- Cleaning and gauging runs completed and the tools inspected on receipt to confirm the bore is clear
- Dewatering and drying proved by measurement before the line is accepted
- As-built survey of the full alignment, crossings and protection, issued to the pipeline operator
Safety watchpoints
- Excavation collapse, flooding and buried services along a route that crosses hundreds of other assets
- Heavy plant working in close formation on a moving front, with lifting operations running continuously
- Working next to live roads, railways and navigable waterways under other operators' possession arrangements
- Working over and in water at river crossings and at the landfall, with drowning risk and changing conditions
- Offshore marine operations, vessel transfers and diving or remote vehicle work under weather limits
- Suspected unexploded ordnance along parts of the route and on the seabed, surveyed for and cleared before work
- Stored energy during pressure testing, with exclusion zones set and enforced for the duration
- CO2 held at pressure in a completed line is a hazard the designer assesses and the pipeline operator manages through the route safety case, valve arrangements, venting design and emergency planning
Common defects to hunt
- Weld defects accepted under commercial pressure and then buried, becoming a dig-up years later
- Coating damaged during lowering in and not detected, giving corrosion a start point
- Insufficient depth of cover in sections where the ground was harder than expected
- Land drains cut and never reconnected, producing waterlogged fields two seasons later
- Topsoil and subsoil mixed during reinstatement, permanently reducing land quality along the easement
- Water left in the line after testing, undermining every upstream decision about dryness and materials
- As-built records incomplete or inconsistent, so the operator cannot inspect what they cannot locate
- Crossings agreed verbally with third parties and never documented, resurfacing as a dispute after handover
How long does CO2 Transport Pipelines take?
Typical duration: Consents and land access commonly run for two to four years; onshore construction of a long route takes one to two seasons once the spread is moving, and offshore lay is measured in weeks of vessel time inside a much longer campaign..
Related processes
- Site Civils & Heavy Foundations
- Capture Plant Installation
- Compression & Conditioning
- Injection Wells & Commissioning
- Onshore buried pipeline - method
- Offshore subsea pipeline - method
- Repurposed existing pipeline - method
- Shipping and marine transport - method
- Carbon Capture & Storage (CCUS) sector guide
- Utilities & Energy - group of sectors