Year: 2026
Type: preprint
Abstract: Reaching net-zero emissions by 2050 requires both steep reductions in anthropogenic CO₂ and active carbon dioxide removal (CDR) to offset hard-to-abate sources, with CDR projected to account for roughly 15-20% of current greenhouse gas emissions.Ocean alkalinity enhancement (OAE), which accelerates mineral weathering to increase oceanic CO₂ uptake, is among the most promising marine CDR strategies, yet large-scale deployment remains largely conceptual and a consolidated implementation framework is lacking.Here, we develop a comprehensive OAE process chain structured around five themes -initial planning and considerations, preceding steps, deployment, monitoring, reporting and verification (MRV), and carbon uptake -systematically identifying the environmental, technical, and social considerations for mineral-based OAE across coastal, river, and openocean settings.Our synthesis shows that mineral dissolution, environmental interactions, and CO₂ uptake potential have received much attention through experiment and model studies.In contrast, critical gaps remain in technoeconomic analyses covering mineral acquisition, transport and deployment logistics, and resource capacities, as well as in social and legal dimensions, including societal acceptance, regulatory frameworks, and MRV accountability.We conclude that OAE deployment as currently envisioned is likely unfeasible, founded on unrealistic assumptions regarding scale and logistics, though the fundamental CDR potential of OAE remains compelling.Large-scale application will require approaches that integrate into existing infrastructure as well as product-, service-and revenue-streams, diverging substantially from current paradigms.We identify the absence of field-scale experiments as the most critical bottleneck limiting the development and maturation of OAE.safe and sustainable application of OAE. Initial planning and considerationsThe primary action for the implementation of OAE (and any given CDR-approach) is the assessment of the feasibility and desirability of the considered measure.For this, overarching questions that need to be addressed include whether a considered OAE approach is technologically and economically viable, environmentally safe, and socially acceptable.The outcome of each of these questions may vary considerably, depending on the chosen approach, the aimed scale of implementation and the considered location.These determine governing laws and regulation, conflicting assets, societal perception, environmental suitability, sensitivity and risks and available resources for implementation that need to be addressed.Further, following the initial confirmation that an OAE intervention is feasible and desirable, ongoing reevaluation is crucial to maintain its feasibility and desirability. Locality as a key parameter for feasibility and desirability assessmentsApart from the chosen approach, arguably the most relevant consideration for the assessment of the feasibility and desirability of an OAE approach is the locality where it is implemented (fig 2).The choice of location will determine (1) the environmental suitability of the measure, including CO2 uptake-and storage capacity, which in turn affects the environmental risk of the intervention, (2) governing law and regulations for the OAE approach depending on the jurisdiction of the location, which, to a degree, reflects the societal perception of the OAE measure and, (3) available resources, including required feedstock, infrastructure, power supply and skilled labor force, which may be in collaboration or competition with existing and future assets and revenue streams from industries and local communities.Based on the outcome of these three overarching dimensions, one can address the question whether an OAE measure at a specific location can be technologically viable, environmentally safe, economically viable and socially acceptable. Environmental suitabilityThe environmental suitability of OAE at a given location is crucial, as the chemical and physical reactions and mechanisms of OAE as well as the prevailing physical and biogeochemical processes and ecosystem of the selected environment are non-negotiable and fundamentally determine whether OAE is technologically viable and environmentally safe in the region.The processes that impact the environmental suitability are covered in detail in this work and include the feedstock acquisition (section 3.1.);the capacity and means for alkalinity addition to sea-or freshwater (section 4.1.-4.4., 4.7., 4.8.); the dissolution capacity of the feedstock (section 4.5.& 4.6.); the CO2 uptake and storage potential (section 4.8.); as well as the impact on additionality of the intervention (4.9.).Depending on the chosen measure and scale of implementation, the physical and biogeochemical properties of the region will constrain the CDR potential and risks during and after implementation, which may impact the suitability of the OAE measure. Societal perception, governing law & regulationsAppropriate regulatory frameworks and positive societal perception are essential for the safe, sustainable, and broadly accepted implementation of OAE.Although societal dimensions of OAE remain understudied (Lück et al. 2025), large-scale deployment will require alignment with public priorities.Historically, public acceptance has proven decisive for the success of emerging technologies, independent of their demonstrated safety or efficacy (Satterfield et al. 2023).The case of genetically modified crops illustrates this: despite scientific consensus on safety, environmental compatibility, and production efficiency, public resistance has been substantial.As
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
Funder: European Commission
OpenAlex ID: W7212142082