08 Jun 2023
 | 08 Jun 2023
Status: this preprint is currently under review for the journal SP.

Assessing technical aspects of ocean alkalinity enhancement approaches

Matthew Eisaman, Sonja Geilert, Phil Renforth, Laura Bastianini, James Campbell, Andrew Dale, Spyros Foteinis, Patricia Grasse, Olivia Hawrot, Carolin Löscher, Greg Rau, and Jakob Rønning

Abstract. Ocean alkalinity enhancement (OAE) is an emerging strategy that aims to mitigate climate change by increasing the alkalinity of seawater. This approach involves increasing the alkalinity of the ocean to enhance its capacity to absorb and store carbon dioxide (CO2) from the atmosphere. This chapter presents an overview of the technical aspects associated with the full range of OAE methods being pursued and discusses implications for undertaking research on these approaches. Various methods have been developed to implement OAE, including: the direct injection of alkaline liquid into the surface ocean, dispersal of alkaline particles from ships, platforms or pipes, the addition of minerals to coastal environments, or the electrochemical removal of acid from seawater. Each method has its advantages and challenges, such as scalability, cost-effectiveness, and potential environmental impacts. The choice of technique may depend on factors such as regional oceanographic conditions, alkalinity source availability, and engineering feasibility. This chapter considers electrochemical methods, the accelerated weathering of limestone, ocean liming, the creation of hydrated carbonates, and the addition of minerals to coastal environments. In each case, the technical aspects of the technologies are considered and implications for best-practice research are drawn. The environmental and social impacts of OAE will likely depend on the specific technology and the local context in which it is deployed. Therefore, it is essential that the technical feasibility of OAE is undertaken in parallel with, and informed by, wider impact assessments. While OAE shows promise as a potential climate change mitigation strategy, it is essential to acknowledge its limitations and uncertainties. Further research and development are needed to understand the long-term effects, optimize techniques, and address potential unintended consequences. OAE should be viewed as complementary to extensive emission reductions, and its feasibility may be improved if it is operated using energy and supply chains with minimal CO2 emissions.

Matthew Eisaman et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on sp-2023-1', Anonymous Referee #1, 07 Aug 2023
  • AC1: 'Comment on sp-2023-1', Phil Renforth, 31 Aug 2023
  • RC2: 'Comment on sp-2023-1', Justin Ries, 14 Sep 2023

Matthew Eisaman et al.

Matthew Eisaman et al.


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Short summary
Ocean alkalinity enhancement technologies refer to various methods and approaches aimed at increasing the alkalinity of seawater. This chapter explore technologies for increasing ocean alkalinity including electrochemical-based approaches, ocean liming, accelerated weathering of limestone, hydrated carbonate addition, and coastal enhanced weathering, and suggests best practices in research and development.