In this episode of Plan Sea, hosts Anna Madlener and Wil Burns sit down with Dr. Phil Renforth and Dr. Mijndert Van der Spek of Heriot-Watt University to unpack their newly published, harmonized framework for evaluating the viability of ocean alkalinity enhancement (OAE) pathways. Moving beyond lab-scale assumptions, their approach integrates techno-economic analysis (TEA) and lifecycle assessment (LCA) to allow the exploration of 54 known OAE variations and how they perform under future, decarbonized energy scenarios. The conversation highlights why real-world data, a cleaner energy grid, and feasibility assessments are important for determining which OAE pathways will deliver results in global scale carbon removal.

With any emerging solution, both feasibility and cost must be effectively evaluated. Renforth and Van der Spek combine two essential lenses – techno-economic analysis (TEA) and lifecycle assessment (LCA) – to build a comprehensive picture of OAE’s real potential. TEA determines if a pathway is economically viable and scalable, while LCA screens for its full environmental impacts, not only if it is net-negative, but also whether it engages in “burden shifting,” or solving one problem while creating another. Operating far beyond “carbon balancing,” LCA works across a range of categories, from greenhouse gas emissions to terrestrial and marine acidification, resource use, and pollution. Together, the two tools are meant to provide a level of quantification for decision-makers investigating the viability of any CDR approach.

In looking at the framework, Dr. Renforth and Dr. Van der Spek began by introducing the framework’s structure through a case study of BPMD and its functionality as OAE technology. Rather than offering predictions, the framework helps to show how different technologies perform under current assumptions. This means the framework should not be viewed as forecasting long-term outcomes on its own, but instead as a tool to see how each pathway changes.

While these tools are powerful, they are incomplete and alongside rigorous research into the broader social, regulatory, and ethical implications of each potential pathway. For example, LCA aims to measure global stressors by normalizing impacts, but it does not have the ability to detect localized effects. This highlights that any comparison drawn from the framework must be paired with site-specific environmental assessments. Together, these layers of analysis provide a more realistic understanding of where OAE pathways may be within reach.

Join us as we dive deeper into this framework and how it aims to spur further evaluation and innovation in OAE by listening to the episode above! Subscribe on your preferred podcast platform and find the entire series here.

ACRONYMS / CONCEPTS:

• CDR: Carbon Dioxide Removal
• OAE: ocean alkalinity enhancement
• TEA: Techno-Economic Analysis
• LCA: Lifecycle Assessment
• BPMED: Bipolar Membrane Electrodialysis

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this episode of Plan Sea, hosts Anna Madlener and Wil Burns dive deep into the new Biogeosciences special issue focused on the environmental safety of ocean alkalinity enhancement (OAE). This episode’s guests are Dr.Lydia Kapsenberg and Dr. Tyler Cyronak who helped edit the special issue. Compiling more than 20 studies, the special issue serves as a “one-stop shop” of the latest peer-reviewed science on the environmental safety of OAE — ranging from responses of micro algae and corals, to the influence of biogeochemical cycling and trace metals. Tune in as we unpack what insights these studies collectively suggest and discuss what it means for next steps in environmental safety research for OAE.

The volume of OAE research has grown dramatically in recent years — increasing four-fold over the last five years. The Biogeosciences special issue shines a light on this rapidly evolving landscape and offers a tool for researchers, funders, regulators, and other partners to access centralized information on potential ecological risks, environmental monitoring standards, and feedstock safety related to multiple OAE approaches.

Throughout the discussion, many themes arise, including the question: How important is it to understand both system-wide patterns and local ecological realities? Lydia and Tyler highlight that while the Biogeosciences studies suggest that many phytoplankton species appear to be resilient under expected OAE conditions, local species and ecological contexts must still be factored into any field research design. This is where researchers have an important responsibility to meaningfully engage with communities on what matters most for their local marine ecosystems and align planned environmental monitoring efforts accordingly.

For researchers, policymakers, and communities assessing OAE’s environmental safety as a potential climate solution, the Biogeosciences special issue offers a crucial early evidence base and a clearer picture of what questions come next.

As mentioned during the episode, Carbon to Sea’s Environmental Impact Monitoring Framework is now available for public review and comment here, through December 12th. Carbon to Sea and the Prince Albert II of Monaco Foundation are also currently soliciting proposals for scientific research on the safety of OAE on commercially and culturally valued marine species. You can view the full funding opportunity and submit a proposal by January 16, 2026.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal.


ACRONYMS / CONCEPTS:

• CDR: Carbon Dioxide Removal
• EPA: Environmental Protection Agency
• MRV: monitoring, reporting, and verification
• OAE: ocean alkalinity enhancement
• OAEPIIP: Ocean Alkalinity Enhancement Pelagic Impact Intercomparison Project

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this edition of Plan Sea, hosts Anna Madlener and Wil Burns kick off season three of the podcast with Woods Hole Oceanographic Institution (WHOI) researchers Dr. Adam Subhas and Jennie Rheuban to discuss the LOC-NESS project — a small-scale, open-ocean research trial on ocean alkalinity enhancement (OAE). The project’s co-principal investigators join Anna and Wil to recount the process of receiving a first-of-its-kind permit from the U.S. Environmental Protection Agency (EPA), the role of local community engagement, and the project’s early findings.

A few weeks ago, WHOI completed its highly controlled research trial in the Gulf of Maine to study the environmental safety and efficacy of OAE as a carbon dioxide removal technique. Approved by the EPA after a two-year, rigorous permitting process, the LOC-NESS project introduced small amounts of purified sodium hydroxide – a compound often used to balance the pH of drinking water – to the ocean surface waters, along with a harmless red dye to help track it. This field study came after years of preparation and development, including extensive laboratory experiments, ocean modeling, and a growing body of scientific literature.

Dr. Adam Subhas is an Associate Scientist at WHOI and the project lead for LOC-NESS. Adam credits the project’s success so far to the comprehensive preparation and collaboration between WHOI scientists and EPA staff — on everything from ocean modeling and biogeochemical impact evaluation, to engaging communities and local industries on what to expect from the research. He also talks about how their pursuit of the first-ever ocean carbon dioxide removal (oCDR) permit under the Marine Protection, Research, and Sanctuaries Act of 1972, helped the LOC-NESS team refine their procedures, improve their approach, and make the project more responsive to feedback from their community.

Jennie Rheuban is a WHOI Research Specialist and serves as a co-principal investigator for LOC-NESS. Jennie points to community engagement as a critical component of LOC-NESS’s development, recounting the project’s years-long effort to engage with questions from a range of stakeholders, including the fishing community. By emphasizing its position as an independent scientific research project without commercial ambitions, WHOI was able to cultivate credibility and gather important community inputs that shaped the scope and methodologies of the research. For example, the team spent additional time researching types of fish larvae in potential field trial regions to bring that information back to the local fisherman.

Looking ahead, LOC-NESS researchers will continue to analyze data gathered during this summer’s trial to understand the impacts and efficacy of the alkalinity dispersal.

More information about LOC-NESS’s findings will be shared at the Ocean Sciences Meeting in February 2026.

Plan Sea is a semi-weekly podcast exploring ocean-based solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.