A FUTURE CONCEPT
LIMENET / OCEAN ALKALINITY ENHANCEMENT
Two vessels. A shared course.
A new way to distribute alkalinity at sea.
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01 / THE IDEA
Adding alkalinity can increase seawater’s capacity to take up CO₂ from the atmosphere.
Limenet is exploring how to deliver that alkalinity across a broad area of the ocean. In this future concept, a bulk carrier and a support vessel travel together, towing a floating distribution line fitted with submerged outlets.
The idea combines controlled delivery, movement through fresh seawater and environmental monitoring. The aim is to enable durable carbon removal, with performance and environmental effects to be demonstrated through research and validation.
The images on this page are concept renderings from Limenet’s storyboard. They illustrate a proposed system, rather than a full-scale installation already operating at sea.
THE SYSTEM, AT A GLANCE
Each part has a different job.
Together, they create a moving delivery system.
AERIAL VIEW / SYSTEM GEOMETRYCarries the alkaline material in enclosed holds and supplies the distribution system.
Maintains the other end of the line while coordinating course, separation and towing.
Connects the sterns in a broad trailing curve and carries the delivery modules.
Indicative dimensions from the concept storyboard. Renderings are not to scale; final geometry requires naval and engineering validation.
02 / FROM SHIP TO SEAWATER
Follow the material from the vessel
to the submerged outlets.
The carrier provides storage for the alkaline material used during the operation.
The distribution line is supplied from the vessel and follows behind it as the system advances.
The support vessel helps maintain the line’s spread as both ships move on coordinated courses.
04 / RELEASE BELOW THE SURFACE
Submerged horizontal outlets introduce the alkaline liquid into the surrounding seawater at multiple points along the line.
Close to each outlet, the jet mixes with seawater. As the vessels move forward, the released material is carried aft relative to the system and diluted by turbulence and currents.
The outlets deliver alkalinity.
Atmospheric CO₂ enters through the sea surface over time.
03 / MOVEMENT AND MIXING
The initial jet and the larger treated-water
footprint are two different scales of motion.
Direction of travel
Mixing continues behind the vessels.
Qualitative schematic. Particle speed, colour and spacing do not represent measured flow or concentration.
Alkalinity is introduced at distributed outlets, rather than from a single discharge point.
Both vessels maintain a coordinated heading. In their frame of reference, the released water moves backwards relative to the ships and hose.
The treated-water footprint extends downstream of the release points along both arms and the trailing section. Currents, waves and turbulence shape how it spreads.
The line is a delivery system, not a barrier enclosing the sea. Actual dispersion depends on operating conditions and local ocean dynamics.
04 / THE CARBON CONNECTION
Alkalinity is seawater’s acid-neutralising capacity. Increasing it changes the balance of dissolved carbon and can create conditions for additional atmospheric CO₂ uptake.
Adding an alkaline substance changes seawater chemistry and initially raises local pH.
Lower dissolved CO₂ can drive transfer from the air into the ocean. The rate depends on gas exchange, mixing and circulation.
The additional carbon is held in dissolved bicarbonate and carbonate forms, within the ocean’s natural carbon chemistry.
This process takes time. The moment of release is not the moment when all associated atmospheric CO₂ has been removed.
Net removal must be verified. Uptake estimates must account for material production, energy use, vessel operations and other lifecycle emissions.
05 / OBSERVE, UNDERSTAND, ADJUST
From measurements in the water
to evidence of carbon removal.
The buoy illustrates how monitoring equipment can accompany the operation.
Submerged instruments and water sampling help characterise conditions in and around the treated water.
Establish background chemistry and ecological conditions before delivery, with reference measurements outside the treated area.
Combine observations of pH, carbonate chemistry and physical conditions with checks for precipitation and environmental effects. Dosing and dilution must keep changes within site-specific operating limits.
Use validated models, field observations and lifecycle accounting to estimate additional CO₂ removal and report uncertainty.
A buoy alone cannot verify carbon removal. Instrument selection, sampling design, operating limits and responses to unexpected conditions are part of the research and validation programme.
THE PATH AHEAD
This page presents Limenet’s vision for future ocean alkalinity delivery. The engineering, material formulation, operating envelope and environmental response require further development and testing.
Progress towards deployment depends on evidence: reliable mixing, retained alkalinity, assessed ecological effects, robust carbon accounting and the relevant permissions.
Back to the full pictureREAD FURTHER
Visual concept and indicative geometry: Limenet storyboard, 14 September 2026. Scientific principles: OAE Best Practices Guide, carbonate chemistry and MRV chapters. The proposed vessel system is presented as future development.