Removing CO2 from the atmosphere and the Desarc-Maresanus project

One year after the launch of the “Desarc-Maresanus” research project run by Politecnico di Milano and the Euro-Mediterranean Centre on Climate Change with the support of Amundi and the collaboration of CO2APPS, the main results are ready to be presented.

“Desarc-Maresanus” studied an alkalinization process to simultaneously address two environmental problems of enormous concern: the increase of the concentration of carbon dioxide (CO2) in the atmosphere and the resulting acidification of the oceans. The process involves spreading calcium hydroxide on the surface of the sea, which would increase the seawater’s capacity to provide a buffer to the acidity, halting the dangerous decrease of pH. This, in turn, can foster an additional removal of CO2 from the atmosphere, generating negative emissions. More specifically, a detailed analysis was done of the technical and economic feasibility of this process, its environmental balance, and the benefits for the marine sector, focussing on the Mediterranean basin.

The main points addressed by the Desarc-Maresanus research project are the following:

  • A modeling study showed how spreading calcium hydroxide on the surface of the sea would make it possible to counteract the existing trend of acidification of the Mediterranean, which is currently in line with what is happening in the oceans worldwide. The calcium hydroxide combines with water and the dissolved CO2, which increases the seawater’s capacity to act as a buffer against the acidification, while making it possible to counteract the decrease of pH.

  • The dispersion of calcium hydroxide in a liquid suspension after its release from a ship was studied using a fluid dynamic model. This has shown the feasibility of dispersing large quantities, thanks to the great turbulence caused by the propeller and by the ship’s wake.

  • Various calcium hydroxide dispersion scenarios were studied for the Mediterranean Sea, considering various types of ships, and the potential for dispersion on a global scale based on current maritime traffic was evaluated. Dispersion by existing ships on their commercial routes has proven to be the most efficient solution.

  • Innovative systems were studied for storing the additional CO2 generated by the process, in order to allow the generation of negative emissions. They include the storage in the deep sea in the form of bicarbonates, or directly inside glass capsules. Detailed simulations of the latter were done to evaluate their mechanical strength. The conditions that could make the various options more or less advantageous were discussed, in relation to the local context, as well as indications for further research needed to ensure that the potential environmental impacts are reduced to a minimum.

  • The capital and operational costs of the new process were assessed and are competitive with the expected price of CO2 on the carbon market envisaged for the coming decades, following a serious implementation of a carbon tax.

  • The overall process was also evaluated with a life-cycle assessment (LCA), that has given encouraging results for different variations of the process based on different types of fuels. Various range of benefits, drawbacks, and technological challenges are present, that must be tackled with future research.

According to Prof. Stefano Caserini, Professor of Mitigation of Climate Change at Politecnico di Milano and Project Leader for the research: “The results attained are very interesting and are another step forward, making us confident that it is possible to remove CO2 from the atmosphere at prices that are not prohibitive, while also providing an answer to the great problem of acidification of the sea. More research is required, on both the technological process and interactions with the environment, but these initial results are promising. We know that we need to reduce greenhouse gas emissions quickly and drastically, and with this project we have begun to work on doing even more”.

Prof. Mario Grosso, Scientific Coordinator of the Research for Politecnico di Milano, added: “The time has come to propose something really ambitious to combat climate change and the acidification of the oceans. The encouraging results of this project come at the most favourable time, precisely when we are entering the decisive decade for dealing with these epochal challenges, and when the European Union is also proposing strong, concrete mitigating strategies”.

Dr. Simona Masina, Director of the Ocean Modelling Division at the Euro-Mediterranean Centre on Climate Change Foundation, stated: “As has been pointed out in the latest IPCC reports as well, simply reducing CO2 emissions will not suffice for combating the climate crisis on our planet. The modeling studies done in Desarc-Maresanus research project indicate how an adequately sized alkalinization process could contribute to simultaneously mitigating the two main problems caused by high anthropogenic CO2 emissions: global warming and acidification of the ocean”.

Paolo Proli, Head of Retail Distribution di Amundi SGR, concluded: “Once again in 2020 we have renewed our economic support to the Desarc-Maresanus research project, because attention to the questions of sustainability and combating climate change is one of Amundi’s long-term commitments, that cannot stop at a single initiative, but permeates deeply into our Company – from investment, to voting policies at shareholders meetings, and initiatives in favor of the environment, with a social impact”.

Project website: http://www.desarc-maresanus.net

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Cristina Perini
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