Lowered onto the seabed of Liverpool Bay in early October, a 4,817 ton platform is set to carry carbon into wells that once gave up natural gas
A barge crane eased a steel structure down onto a jacket already driven into the floor of the Irish Sea.
The water here is only around 100 feet deep.
But the wells below it are far from empty of history.
A field that once exported energy now imports a waste stream, using reversed flow and new injection wells drilled into formations the industry already understood.
For decades they gave up natural gas to pipelines running back to the Welsh coast.
Now the same pipes are being asked to carry something downward instead of up.
That reversal is what the first H2 has to explain.
Why send carbon back down the same pipes that once brought gas up
The logic is almost embarrassingly simple once laid out. A depleted gas reservoir is, by definition, a rock formation that has already proven it can hold a gas under pressure for millions of years without leaking.
Engineers did not have to go looking for a sealed vault. They already had the geological map of one, which saved years of exploration work.
So the project reuses the plumbing rather than building new. The newly installed platform, known as Douglas CCS, connects directly to an existing offshore pipeline network that used to move gas inland.
The carbon dioxide does not get pumped as a gas in the everyday sense. It is compressed into a dense phase, closer in behavior to a liquid, which lets the same diameter of pipe move far more mass per hour. A field that once exported energy now imports a waste stream, using reversed flow and new injection wells drilled into formations the industry already understood.
The platform itself, broken into steel and weight
Picture the structure in three pieces, because that is how it was built and shipped. There is a working deck on top, the part where pipes, valves and control rooms sit, weighing 1,885 metric tons on its own.
Beneath that sits a supporting steel jacket, the lattice tower that holds the deck clear of the waves, at 1,755 metric tons. Anchoring the whole thing to the seabed are eight foundation piles driven deep into the rock, adding a further 730 metric tons between them.
The total comes to approximately 4,817 US tons, or 4,370 metric tons, and that weight was lowered onto a seabed most of its future operators will never see with their own eyes. The platform was delivered in less than 18 months after the contract was awarded.
It went in during the first half of October, part of what the operator describes as one of two UK Track 1 carbon capture clusters now under construction, alongside the Northern Endurance Partnership in Teesside.
What the data actually confirms, and where it came from
The claim rests on documentation from the operator itself rather than a secondhand summary. Eni CCUS Holding, owned jointly by Eni and Global Infrastructure Partners, announced that Liverpool Bay CCS has completed installation of the Douglas CCS platform, a statement made public once the lift was physically complete.
Because the structure replaces rather than duplicates old infrastructure, the engineering record matters as much as the announcement. The project repurposes the existing offshore natural gas import pipeline from Point of Ayr into a CO2 export line, with carbon transferred for injection into depleted reservoirs at the Hamilton Main, Hamilton North and Lennox platforms.
That detail, three named satellite platforms feeding a single hub, is what turns a press release into a traceable engineering fact. Each field has decades of production records that regulators can check injected volumes against going forward.
Where the project still falls short of finished
None of this means gas is flowing into the ground yet. The platform is a hub, not a pipeline network, and its installation forms part of a wider construction program across the Liverpool Bay CCS network, now approximately 50 percent complete.
Around 60 percent of spending has gone to UK firms, supporting more than 2,000 construction jobs, with a further 200 to 300 lasting roles expected through the platform’s 25 year operation. So the honest caveat is timing.
Permits allow preparation of the stores for initial injection of 4.5 million metric tons of CO2 per year starting as soon as mid 2028, well after this steel found its footing on the seabed. The platform being seated does not mean the valves are open.
Even so, the volumes on the table are large by any industrial measure. The reservoirs will accept a combined 109 million metric tons of CO2, spread across Hamilton Main at 53 million metric tons, Hamilton North at 18 million metric tons, and Lennox at 38 million metric tons.
What this means for the fields it reuses, and what stays open
For the Hamilton, Hamilton North and Lennox fields, the platform marks a second working life rather than a retirement. Wells plugged or idled as gas output fell are candidates to be sidetracked and recompleted as injection points as the program progresses.
That is a far cheaper path than drilling fresh holes through virgin rock. And it echoes a broader pattern across depleted gas basins, where falling output and rising decarbonization pressure increasingly meet in the same field, much like the record setting discovery at Gullfaks South.
It is the same calculus behind projects such as the Gullfaks South find in Norway, where operators are finding new value in formations once thought largely spent, and it tracks with forecasts that producing basins still have long operating runways ahead of them.
What remains unverified is the longest timescale of all: whether carbon dioxide will stay locked in these rocks for centuries the way methane did for millions of years. That answer will come slowly, from monitoring wells and a reservoir that has already kept one secret successfully for a very long time.
Hugo is an engineer with strong technical expertise. Multilingual from an early age, his writing combines technical clarity with a strong interest in science and energy.
