Ocean alkalinity enhancement is shifting from theory to practice as new research standards, U.S. government grants exceeding $55 million, and a wave of startups accelerate efforts to test the method in real ocean settings. Yet the field remains in its infancy, with scientists stressing the need for rigorous monitoring, clearer verification tools, and deeper understanding of ecological risks before large-scale deployment moves forward. Full article >>
Planetary Technologies is accelerating its ocean-alkalinity work after delivering the world’s first OAE-based carbon credits and securing new funding, including a $1 million XPRIZE award, to expand its magnesium-hydroxide projects in Canada and beyond. The company is now emphasizing “scaling out” by deepening community engagement after opposition in Cornwall, aiming to build public trust as it ramps up deployment. Full article >>
Italian ocean-alkalinity start-up Limenet is accelerating its commercial push, joining the Carbon Business Council while expanding operations around its modular plant in Sicily, which converts CO2 into stable bicarbonate for long-term ocean storage. Backed by new certification, fresh capital, and its first major carbon-credit sale, the company aims to scale removal capacity to 2,000 tons a year and position OAE as a credible climate-tech sector.
Limenet's project uses limestone feedstock for OAE, rather than basalt. Full article >>
Basics of OAE
The OAE process is similar to the ERW process in that both processes involve crushing or to a powder (to make it more soluble), and then spreading the rock powder on the ocean surface (OAE) or a land area (ERW). OAE aims to buffer (lower the acidity) of ocean water which would accelerate the naturally-occurring process of atmospheric CO2 (in rain water) dissolving in ocean water on the ocean surface.
Chemical reactions in ocean water -
Like ERW, OAE is essentially a series of acid-base reactions. Simplistically speaking, carbonic acid (H2CO3) in rainwater dissolves rock powder, resulting in a chemically neutral solution in ocean water composed of bicarbonate (HCO3-), a base, charge-balanced by calcium (Ca2+) and magnesium (Mg2+)
which are acidic.
Deployment status -
OAE currently is only in the testing stage. There have been no large-scale commercial OAE projects. A small number of research trials are being performed at a few locations by researchers in the public and private sectors.
Environmental impacts -
Potential adverse impacts from OAE include impacts to marine life from trace metals (e.g., nickel and chromium) in rock powder and chemical components generated in the OAE reactions (e.g., bicarbonate, calcium, manganese, and iron). Clouding ocean water with rock dust could also adversely impact marine life.
Carbon negative status -
OAE requires a significant amount of energy to mine, grind, and transport rock powder feedstock. Low- or zero-carbon energy sources will be necessary for an OAE project to be carbon negative (i.e., remove more carbon dioxide than the project produces). A cradle-to-grave
assessment of a project is necessary for verifying the project will be carbon negative.
Cost per ton of CO2 removed -
The cost of OAE is poorly defined due to OAE's untested status. Costs will include: mining, grinding, transporting, spreading rock powder, and
. The amount of electricity needed to grind 1 tonne of basalt is to be 60 . Assuming electricity use is 80 kWh, and electricity costs $0.20 (USD) per kWh, grinding cost for 1 tonne of basalt would be $16.
Measurement, reporting, and verification () -
Accurate verification of carbon removal amounts will be necessary if the OAE industry will be funded by the sale of carbon credits. Verification include sensors which directly measure alkalinity of the water (more bicarbonate equals more alkalinity) and water samples (which can be analyzed for bicarbonate and alkalinity in a laboratory). Computer modelling is also an important part of verification.
Side benefits of OAE -
Making ocean water more alkaline via OAE may help the adverse effects that ocean acidification is predicted to have on calcifying marine life (e.g., corals, molluscs, plankton).
CO2 storage durability -
CO2 converted to bicarbonate (HCO3-) and stored in ocean water is considered to be virtually permanent .
Long-term global CDR potential -
Future implementation of OAE as a CDR method is unknown. The ocean may be able to store
of tons of CO2 with limited changes in bulk chemistry. This compares to the 1,000 (1 trillion tons) of CO2 needing removal from the atmosphere within the next century according to the
.
