Engineered subsea capsules for permanent CO₂ storage.
Dioxink develops modular geopolymer capsules for the permanent storage of carbon dioxide at depths between 400 and 6,000 metres. The capsule is designed for the deep-sea pressure regime, with hydrate self-sealing as a passive secondary barrier.
Storage is the bottleneck.
The world needs to scale permanent CO₂ storage roughly one hundred-fold by 2050. Subsurface injection cannot reach that scale on its own, because the geology required is not located where most emitters operate.
Permanent CO₂ storage is projected to grow from approximately 50 megatonnes per year today to over 6 gigatonnes per year by 2050. Facilities currently planned or under construction will cover only around 244 Mt by 2030.
Suitable geological formations are unevenly distributed across Europe, with most usable capacity concentrated in the North Sea and on the Norwegian continental shelf. Inland industrial emitters, island regions, and direct air capture facilities sited by power availability are left with few options.
Decentralised engineered storage closes that gap. Build storage objects to specification, rather than search for naturally occurring reservoirs.
Three principles in combination.
Each principle has been studied independently in the literature. The integration of all three into a single deployable system has not.
Geopolymer envelope.
An aluminosilicate cement formulation, incorporating locally sourced recycled aggregates, engineered for low permeability and saltwater resistance across the operating pressure regime. Compressive strength target above 40 MPa. The geopolymer chemistry is sourced from the institution that originated the field.
Hydrate self-sealing.
At deep-sea pressures, CO₂ remains in its liquid phase. Any breach in the envelope brings the stored CO₂ into contact with seawater, which forms clathrate hydrates at the interface. The hydrate cage passively re-seals the breach from within. A second barrier engineered into the system, not added on.
Impurity tolerance.
The capsule is mechanically isolated from any pipeline or geological reservoir. CO₂ streams from post-combustion, direct air capture, or biogenic sources can be stored without expensive purification. Realistic impurity windows for H₂O, SO₂, NO₂, N₂, O₂ are modelled within the SEAQUEST programme using established CO₂ thermodynamics tools.
Built to specification.
Two geopolymer half-spheres, assembled and filled with liquid CO₂ before deployment. The hydrostatic pressure at depth maintains the contents in the liquid phase. Every parameter is set in advance.
SEAQUEST, 2026 to 2030.
Dioxink is currently at Technology Readiness Level 2 and advancing to TRL 4 through SEAQUEST, a four-year research programme co-funded by the European Innovation Council under the Pathfinder Open scheme.
The programme is built around a credible TRL 4 claim by 2030, with deliverables in formulation development, container structural optimisation, long-term durability validation, and end-application feasibility, supported by extended laboratory validation under simulated deep-sea conditions.
Dioxink coordinates the programme from Brussels and leads the formulation and end-application work, with specialist contributions on high-pressure validation, advanced manufacturing and life-cycle assessment, and structural modelling and CO₂ thermodynamics from research partners across Europe.
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