• Electrochemical technologies, as applied to mCDR, are very new. Because most field experiments are in the planning phases or are underway currently, it is not yet possible to have a comprehensive characterization of benefits, risks, and scaling considerations of electrochemical approaches in real-world settings (i.e. not benchtop). Controlled field experiments across diverse ecosystems to determine marine chemistry and biology impacts and feedbacks are needed (Develop New Modeling Tools to Support Design and Evaluation, Accelerate Design and Permitting of Controlled Field Trials).
• It is challenging to verify additional CO₂ uptake from the atmosphere as a result of electrochemical CDR given the ocean’s dynamic CO₂ flux “background state”. New methodologies are needed to observe additional sequestration from the atmosphere into the ocean (Develop New Modeling Tools to Support Design and Evaluation, Develop New In-Water Tools for Autonomous CDR Operations)
• Laboratory experiments are needed across a range of seawater chemistries because of expected electrochemical CDR variations in seawater total alkalinity and dissolved inorganic carbon^[1]Comments from Dr. Ros Rickaby, ‘Workshop on Ocean-based CDR Opportunities and Challenges, Part 2: Technological and Natural Approaches to Ocean Alkalinity Enhancement and CO₂ Removal’ on 27th January 2021 to characterize environmental impacts (Accelerate Design and Permitting of Controlled Field Trials).
  • Look to the ocean acidification community’s effort to develop standardized protocols for guidance (Gattuso et al., 2015) as the community builds out standardized protocols and treatment levels for consistency and inter-comparability. See the 2023 Guide to Best Practices in Ocean Alkalinity Enhancement as one example (note that while not all electrochemistry is OAE, there is much in common and there are overlapping needs).
• Global, local, and regional predictions of physical, chemical, and biological outcomes and feedbacks of electrochemical CDR from high-resolution models (Develop New Modeling Tools to Support Design and Evaluation)
• Life cycle assessments to calculate net CDR benefits, taking into account all emissions associated with supply chains (Develop CDR Monitoring and Verification Protocols). 

• Current observational technologies (sensors, ROVs, AUVs, etc.) and modeling tools are not widespread and easily available to support field trials with the necessary spatial and temporal frequency of monitoring and sampling (Develop New In-Water Tools for Autonomous CDR Operations)
• In the case of surface seawater alkalinity addition from electrolysis or electrodialysis, cost-effective and safe methods need to be developed that optimize the distribution, dispersal and dilution of any strong chemical bases to avoid impacts of excessively alkaline (pH>9) waters on marine ecosystems. Dilution may require pumping large amounts of seawater, which need to be optimized for energy and cost (Develop New In-Water Tools for Autonomous CDR Operations).
• Offshore deployment of either electrodialysis or electrolysis would require further development to overcome challenges of working in the ocean (corrosion, biofouling, storms, physical and chemical stress on electrodes, catalysts, and membranes, etc.) (Develop New In-Water Tools for Autonomous CDR Operations). 
• Questions remain about how variations in seawater particulate and dissolved organic matter, temperature, and salinity affect electrochemical CDR efficiency (Develop New In-Water Tools for Autonomous CDR Operations). 
  • • Methods of handling chlorine gas produced as a byproduct of seawater electrolysis are needed (Develop New In-Water Tools for Autonomous CDR Operations, Improve Understanding of Markets for Co-Products)
    • Development of feedback control systems that integrate nearby observational data to determine optimal levels of electrochemical CDR (Develop New Modeling Tools to Support Design and Evaluation, Develop New In-Water Tools for Autonomous CDR Operations). 
    • Identifying and understanding how equipment, energy, and cost scale from benchtop experiments to small field experiments to globally-relevant deployments (Develop New Modeling Tools to Support Design and Evaluation, Develop New In-Water Tools for Autonomous CDR Operations, Develop CDR Monitoring and Verification Protocols, Accelerate RD&D Through New Partnerships)

Many of the opportunities and challenges around building public support are not specific to electrochemical CDR, but there are several points of interest specific to electrochemical CDR: 

• Electrochemical CDR faces challenges in terms of public perception regarding potential environmental risks not necessarily faced by more “nature-based” approaches, such as coastal blue carbon restoration (Bertram & Merk, 2020). (Accelerate RD&D Through New Partnerships)

• Complexities of electrochemical CDR pathways inhibit understanding and evaluation by non-technical audiences
• There is a great deal of uncertainty and confusion around any mCDR pathway that relies on adding materials to the ocean. This point applies to both electrochemical alkalinity additions, which return a base to the seawater, and pathways that precipitate out calcium carbonate.
• Earlier ocean iron fertilization experiments^[2]Schiermeier, Q. (2009a). Ocean Fertilization Experiment Draws Fire: Indo-German Research Cruise Sets Sail Despite Criticism. Available online at: https://www. nature.com/news/2009/090109/full/news.2009.13.html could offer opportunities to adopt best practices and avoid mistakes made when building public support for electrochemical CDR. 
• Electrochemical CDR has the advantage that it can be “turned off” more easily than the other approaches, enabling great control over its application

• Clearer communication strategies need to be developed to respond to the “engineering” narrative of electrochemical CDR.