New research maps the American shorelines best positioned to scale up electrochemical marine carbon removal - a technology that could help reshape the nation’s climate strategy.
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Alternative Carbon Removal Strategies Needed
Traditional carbon capture and storage (CCS) captures carbon dioxide (CO2) emissions directly from industrial sources to prevent atmospheric release, but challenges related to scaling and infrastructure gaps prompt the need for alternative carbon dioxide removal (CDR) strategies.
CDR technologies focus on extracting accumulated CO2 from the atmosphere and include natural methods such as afforestation and soil carbon sequestration, which are limited by land competition and capacity.
Engineered solutions like bioenergy with CCS and direct air capture (DAC) operate with less land dependence and higher scalability. Among these, electrochemical methods for marine CO2 removal leverage seawater’s vast potential to absorb and store carbon. Using facilities with seawater intakes optimizes siting by harnessing existing infrastructure.
This study clusters these facilities into regional hubs and assesses them using multiple criteria, including removal potential, affordability, energy sources, local emissions, social vulnerability, facility diversity, and hydrogen infrastructure, to prioritize deployment locations.
The Current Study
Thirty-eight facilities across the US coastline featuring seawater intakes were identified and grouped into five coastal hubs - Northeast, Southeast, South, West, and Northwest - using hierarchical clustering based on geographic proximity.
The analysis considered facility types, including power plants, desalination units, and LNG terminals. To evaluate each hub’s suitability for e-mCDR deployment, seven criteria were established. Five were facility-level averages scaled to the hub, covering CO2 removal capacity (measured in kilotons of CO2 per day), removal affordability (kilograms of CO2 removed per dollar), grid emissions efficiency, local carbon footprint (million tons CO2 annually), and social vulnerability indexed by exposure to environmental and socioeconomic risks. Two additional hub-specific criteria accounted for facility diversity, measured by the Shannon diversity index to reflect the balance of facility types, and the extent of hydrogen management infrastructure, quantified by normalized hydrogen storage, pipeline length, and demand metrics.
The Analytic Hierarchy Process (AHP) was employed to assign weights reflecting the relative importance of each criterion based on expert input and literature review, with CO2 removal capacity weighted most heavily at 24 %, followed by removal affordability and clean energy share at 23% each. The local carbon footprint, hydrogen infrastructure, facility diversity, and social vulnerability carried lesser weights ranging from 4 % to 12 %. The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method combined the weighted, normalized scores to rank the hubs based on overall suitability. Sensitivity analyses tested the robustness of rankings by varying criterion weights and evaluating the impact of excluding specific facility types such as power plants and LNG terminals.
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Results and Discussion
The South, West, and Northeast hubs ranked highest across multiple criteria, each with distinct strengths that support their suitability. The South hub led in removal affordability due to cost-effective electricity primarily generated from natural gas, wind, and nuclear sources in Texas and Louisiana. It also showed high social vulnerability, making it a priority for equitable carbon removal investments.
Despite having the lowest CO2 removal capacity, mainly because of smaller seawater intake capacity, its diversity of facility types and well-established hydrogen infrastructure enhances logistical flexibility and economic feasibility. The presence of large CO2-emitting industries in the oil and gas sectors contributes to the region's high local carbon footprint, but combined with abundant wind energy production and participation in environmental justice initiatives, it remains a strategic location for e-mCDR.
The Western hub exhibited the greatest CO2 removal capacity owing to the high seawater intake primarily from power plants in Southern and Central California. However, higher electricity costs lowered removal affordability. This hub benefits from extensive renewable energy integration and solid hydrogen storage and pipeline infrastructure driven by regional environmental policies. Its weakness lies in limited facility diversity, potentially posing challenges if regulatory or technical issues affect the predominance of power plants for CO2 removal.
The Northeast hub, while not detailed as extensively, is among the leading hubs due to a balance of infrastructure readiness, removal potential, and affordability.
The Southeast hub displayed moderate performance but faced challenges in grid emissions efficiency due to lower clean energy penetration and limited hydrogen infrastructure, tempering its attractiveness despite its affordability and social vulnerability profile.
Conclusion
This study developed a systematic framework combining geographic clustering, multi-criteria evaluation, and decision analysis to identify and rank US coastal hubs for electrochemical marine CO2 removal deployment. The South, West, and Northeast hubs emerged as priority regions, each offering complementary advantages in removal capacity, cost, energy sustainability, and infrastructure robustness. While challenges such as varying energy mixes, infrastructure gaps, and social vulnerability exist, the proposed framework offers a practical tool to guide strategic investments, technology development, and policy design for scalable ocean-based carbon dioxide removal. Future research should expand assessments to other e-mCDR pathways, address technological optimization, and foster integrated policies that support both environmental goals and community equity.
Journal Reference
Refaie A., Afshari M., et al. (2026). Comparative assessment of United States coastal hubs for large scale electrochemical marine carbon dioxide removal. Communications Sustainability. 1, 33. DOI: 10.1038/s44458-026-00035-9, https://www.nature.com/articles/s44458-026-00035-9