Scientists from University of Houston, Columbia University, University of California (UC Davis), and University of California (Los Angeles) performed a study to determine the best locations in the US for placing the major plants for electrochemical removal of carbon dioxide from sea water. This is a technology enhancing the natural CO₂ absorption capability of the ocean.
Today, the World Ocean is already absorbing about one third of man-made carbon dioxide emissions converting the contaminating gas into dissolved forms – carbon acids, bicarbonates and carbonates. The proposed technology known as electrochemical CO₂ removal from sea water serves to facilitate this natural process. The plant is running on electricity; it screens sea water through an electrochemical module. During the electrolysis process the degree of acidity of the medium changes: in the cathodic zone it has a higher degree of alkali facilitating carbon sequestration in the form of stable bicarbonates or solid carbonic minerals. Hydrogen is generated simultaneously. The treated water is returned to the ocean, where it is capable of absorbing more CO₂ from the atmosphere.
But the American researchers became curious: where such plants cleaning ocean from carbon dioxide should be placed? It is economically unfeasible to build new water intakes and industrial infrastructure along the coast line. Hence, they proposed to integrate electrochemical modules into the already existing on-shore facilities. For that they analyzed 38 enterprises pumping big amounts of sea water on a daily basis: power plants with marine cooling, desalination plants and terminals for receiving and exporting liquified natural gas. Such infrastructure is already equipped with water intake and discharge systems, connected to the grid and is located in the industrial zones, which significantly reduces the barriers for technology implementation.
By way of cluster analysis, the facilities were grouped into five regional hubs: North-Eastern, South-Eastern, Southern, Western and North-Western. Each hub was evaluated from the standpoint of seven criteria: potential CO₂ removal capacity (depends on the amount of the pumped water), electricity costs, carbon “cleanness” of the regional energy system, local emissions level, the degreed of development of the infrastructure for handling hydrogen, diversity of sites and social vulnerability index of citizens.
Judging by the totality of all the parameters, the Southern hub covering Texas and Louisiana coastlines including the Big Houston industrial district became the leader. The region combines relatively low electricity costs, well-developed hydrogen infrastructure and high level of CO₂ emissions making the implementation of this technology especially meaningful from the standpoint of climate effect.
The Western hub including the districts on Californian coastline with major water intaking facilities and high share of renewable energy and the North-Eastern hub with significant industrial potential and relatively “clean” energy grid follow by a whisker.
According to the researchers, the next logical step should be the transition from calculations to practice: launching pilot and demo projects in the clusters having the highest potential.
