The Desarc-Maresanus project to remove CO2 from the atmosphere

The Politecnico explores new strategies to prevent climate change and the acidification of oceans

The research project Desarc-Maresanus celebrates one year. It is carried out by Politecnico di Milano and by Centro Euro-Mediterraneo sui Cambiamenti Climatici [Euro-Mediterranean Climate Change Centre] with the support of Amundi, in partnership with CO2APPS.

Desarc-Maresanus studied an alkalinisation process to combat two environmental problems of great significance at the same time: the increase in carbon dioxide (CO2) levels in the atmosphere, and the resulting acidification of the oceans.

The process consists of disseminating calcium hydroxide on the ocean surface. Combining with water through a spontaneous reaction, it increases sea water’s capacity to act as a buffer against acidity, thus preventing a drop in pH levels. This favours removal of CO2 from the atmosphere.

The study conducted a detailed technical and economic feasibility study of this process, its environmental balance, and benefits for the marine sector, with focus on the Mediterranean.

Prof. Stefano Caserini, Professor of Climate Change Mitigation at Politecnico di Milano and Project Leader for the research, explains:

The results achieved are reassuring that CO2 can be removed from the atmosphere at reasonable costs, also providing a solution to the great issue of ocean acidification. More studies are required, both concerning the technological process and interactions with the environment, but these early results are promising.

The Desarc-Maresanus research has achieved some important results:

·         the study of models has revealed that dissemination of calcium hydroxide on the ocean surface would prevent the Mediterranean’s acidification trend; the calcium hydroxide released binds water and CO2 through a spontaneous process, which increases sea water’s capacity to act as a buffer against acidity, thus impeding the drop in pH;

·         the study conducted with fluid dynamics modelling confirmed the high dispersion rate of calcium hydroxide, when it is released in the wake of a ship, thus suggesting the possibility of spreading large amounts of it by either exploiting existing ships or by creating dedicated vessels; calcium hydroxide released in the form of liquid suspension dissolves as a result of the considerable turbulence in the wake of a ship;

·         several scenarios have been studied for the dissemination of calcium hydroxide in the Mediterranean, with various types of ships, and the dissemination potential was also evaluated in a global scale, based on data on existing maritime traffic; dissemination on the part of existing ships seems to be the most efficient solution;

·         innovative systems have been studied to store CO2, which must not be released into the atmosphere, as alternative solutions to traditional geological storage, evaluating the feasibility of the various options, including underwater storage in the form of bicarbonates or in glass capsules; detailed simulations have been carried out on the latter to evaluate their mechanical resistance; conditions that might make the various options more or less advantageous, based on the local context, were discussed, besides the additional research required to guarantee that the potential environmental impact will be reduced to a minimum;

·         various methods are available to remove CO2 from the atmosphere, and the estimated costs of the new process studied are in line with the high prices of CO2 on the carbon market expected for the coming decades;

·         the evaluations made using life-cycle assessment (LCA) methodology show that a number of process variants are possible, which can use various types of fuels, with a different range of benefits, criticalities, and technological challenges that must be tackled in the future.

 The time is right to propose something really ambitious to combat climate change and acidification of the oceans. The reassuring results of this project come at the most propitious time, precisely when we are entering the decisive decade for dealing with these epoch-making challenges, and when the European Union is also proposing strong, concrete mitigating strategies.

says Prof. Mario Grosso, Scientific Coordinator for Research at the Politecnico di Milano.

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