GEOMAR researchers test concrete rubble for ocean alkalinity enhancement

An international research team led by the GEOMAR Helmholtz Centre for Ocean Research Kiel has launched a seven-week experiment in the harbor of Taliarte, Gran Canaria, to test Ocean Alkalinity Enhancement (OAE). The study investigates whether ground concrete rubble can effectively increase the alkalinity of seawater to enhance its ability to absorb CO2 from the atmosphere.

Using twelve mesocosms—large floating test tubes that isolate seawater, plankton, and microorganisms from the surrounding ocean—researchers are comparing the effectiveness of liquid alkalinity sources against ground concrete rubble. The goal is to observe how these substances affect water chemistry and the marine ecosystem. This process mimics natural rock weathering, converting dissolved CO2 into bicarbonate and carbonate to lower the partial pressure of CO2 in the water, thereby facilitating further absorption from the air.

The experiment is part of the OceanAlkAlign project, which seeks to standardize measurement and assessment methods for OAE to provide a robust basis for future climate mitigation decisions. The research is supported by the Canary Islands Marine Research Institute (PLOCAN), located near the testing site.