Ebb carbon dioxide removal (CDR) project Macoma

Ebb Carbon’s Project Macoma represents a pivotal advancement in Carbon Dioxide Removal (CDR) of Direct Ocean capture (DOC). This project demonstrates the operational feasibility and regulatory viability of electrochemical Ocean Alkalinity Enhancement (OAE). Located at the Port of Port Angeles, Washington, the short-term pilot utilizes an electrochemical process to increase seawater alkalinity, thereby accelerating the ocean’s natural capacity to draw down and permanently store atmospheric CO₂ as stable bicarbonate (HCO₃⁻) for over 10,000 years.

The project has achieved critical milestones: it is underpinned by two years of safety and efficacy validation from federal partners (PNNL and NOAA) published in peer-reviewed literature. Crucially, Project Macoma has secured a first-of-its-kind National Pollutant Discharge Elimination System (NPDES) permit, establishing a vital regulatory blueprint for DOC deployment under the US Clean Water Act.

Commercially, the venture is highly validated by a major off-take agreement with Microsoft, which committed to funding the removal of 1,333 tons of CO₂ and holds an option for up to 350,000 tons over the next decade. Ebb Carbon projects achieving a cost structure below $100 per ton of CO₂ by 2028. However, financial viability and carbon negativity are strictly contingent upon the utilization of 100% renewable, low-cost energy, making the energy supply chain the primary scaling constraint. This dual-benefit approach—combining global CDR with local ecological restoration (ocean acidification mitigation)—positions Project Macoma as a high-quality, bankable asset.

1. Contextualizing marine Carbon Dioxide Removal (mCDR)

1.1. The urgent need for CDR and ocean acidification mitigation

The global climate challenge necessitates a comprehensive approach that extends beyond immediate emissions reduction. Scientific consensus indicates that limiting global warming to 1.5 ºC  requires the removal of billions of tons of CO₂ annually by 2050, necessitating a diverse portfolio of CDR technologies. Among these, ocean-based solutions are regarded as essential because the ocean offers the requisite vast surface area and long-term storage capacity necessary for potential gigaton-scale impact.

The atmospheric buildup has instigated a second, equally severe crisis: ocean acidification. As  dissolves into seawater, it forms carbonic acid (H₂CO₃), driving down the ocean’s pH and shifting its chemistry away from its natural, slightly alkaline state. This fundamental chemical alteration threatens marine economies, ecosystems, and key calcifying organisms, such as shellfish and coral reefs. Ocean Alkalinity Enhancement (OAE) is an approach designed to shift seawater chemistry back toward alkalinity, restoring the ocean’s natural buffering capacity and concurrently accelerating the removal of atmospheric.

1.2. Strategic duality and social license to operate

The dual mission of Ebb Carbon’s technology—addressing both the root cause (in the atmosphere) and the direct environmental consequence (ocean acidification)—constitutes a critical strategic advantage for project deployment and scaling.

By combining CDR with the local ecological repair of marine health in the Salish Sea, Ebb Carbon successfully aligns the global climate goals of its corporate partners (e.g., Microsoft) with local economic and ecological preservation goals. This unique, two-pronged approach inherently secures a superior social license to operate, evidenced by the early engagement and input acknowledged from local Tribes, community members, and various governmental regulators who have shaped the project from its inception. This robust community integration is essential for easing regulatory pathways and facilitating the smooth transition from a pilot to scaled commercial operations.

2. Detailed analysis of electrochemical ocean alkalinity enhancement (OAE)

2.1. Physicochemical principles of electrochemical alkalinity generation

Ebb Carbon employs an electrochemical process to artificially accelerate the natural process of ocean alkalization, a process that historically occurs over millions of years. The core mechanism involves drawing in ambient seawater and processing it using low-carbon electricity.

The technology utilizes a stack of ion-selective membranes to separate the water’s components into two primary streams: an acidic solution and a highly basic, or alkaline, solution. The enhanced alkalinity stream, which can achieve concentrations of NaOH ranging from 0.2 to 1.0 mol/L, is carefully measured and monitored before being released back into the ocean. The highly basic output stream instantly achieves two objectives upon discharge: it locally lowers the acidity of the seawater, and it increases the water’s carbonate buffering capacity. This increased alkalinity allows the seawater to absorb additional CO₂ from the atmosphere. This CO₂ is then converted into stable, long-lived bicarbonate ions (HCO₃⁻), ensuring that the carbon is safely sequestered for durations exceeding 10,000 years.

2.2. Technology integration and scalability pathways

The inherent design of Ebb Carbon’s system aims to maximize scalability and minimize infrastructural footprint. The technology is specifically designed for integration with existing industrial facilities that already handle large volumes of seawater. These co-location sites include aquaculture farms, desalination plants, and ocean research laboratories.

By intercepting existing salt water flows at these industrial sites, the technology processes the water before it returns to the ocean. This strategy circumvents the need for building new, large-scale intake and outfall systems, significantly simplifying the engineering and deployment aspects. Furthermore, leveraging existing infrastructure streamlines the permitting process and reduces the potential for adverse ecological impacts often associated with new construction in coastal areas.

2.3. Life cycle assessment (LCA) and energy demand profile

While electrochemical processes offer advantages in efficiency and full electrification, they are inherently energy-intensive due to the need for a sustained electrical potential (voltage) to drive the desired chemical reactions, such as ion separation. Ebb Carbon acknowledges this requirement by committing to using “low carbon electricity” for its operation.

Analysis of the Life Cycle Assessment (LCA) data for electrochemical OAE (referred to as “brine splitting”) reveals a critical dependency for its environmental viability: the process is only carbon negative when 100% renewable energy is used. This is a non-negotiable threshold for commercial success and scientific legitimacy. For instance, LCA data shows that operating the system using grid electricity with a high carbon intensity, such as Spain’s grid mix, results in a carbon positive outcome, emitting 1.38 tons of CO₂ for every ton of CO₂ nominally removed. Conversely, when powered by dedicated renewable sources, such as onshore wind turbines (>3MW), the system becomes highly net negative, emitting only 106 kg of CO₂ for every ton removed.

The reliance on extremely low-carbon energy fundamentally links the system’s technological necessity (net negativity) with its economic target (below $100 per ton of CO₂). The energy requirement represents the primary scaling bottleneck and economic risk for OAE. To achieve the ambitious  target set by the U.S. Department of Energy’s (DOE) Carbon Negative Shot, the Operational Expenditure (OpEx) dominated by electricity cost must be exceptionally low. Therefore, future large-scale deployments must be strictly co-located with dedicated renewable power generation infrastructure, mandating significant capital expenditure in clean energy systems alongside the OAE plants. This integration shifts the investment analysis framework from focusing purely on technological efficiency to evaluating regional renewable energy grid capacity and long-term pricing stability.

3. Project Macoma: Pilot implementation and operational metrics

3.1. Precursor trials: scientific validation at PNNL-Sequim

Project Macoma is strategically built upon a robust foundation of two years of controlled field demonstrations conducted in partnership with the Department of Energy’s Pacific Northwest National Laboratory (PNNL) in nearby Sequim Bay, Washington. This research represented a comprehensive, multi-institutional effort that included scientists from PNNL, NOAA’s Pacific Marine Environmental Laboratory, the University of Washington, and Ebb Carbon itself.

The findings from these trials were subjected to the highest level of scrutiny, resulting in publication in the peer-reviewed journal Frontiers in Environmental Engineering. The research documented the “first-of-its-kind dispersal of electrochemically derived aqueous alkalinity”, managed through the PNNL wastewater treatment facility outfall. This rigorous federal and academic validation confirmed the technology’s safety and efficacy, demonstrating through real-world scenarios that Ebb’s system can operate safely and adhere to existing regulatory requirements. Securing this external, peer-reviewed endorsement is instrumental in countering scientific skepticism often directed at novel mCDR techniques.

3.2. Site selection, operational scale, and timeline

The operational Project Macoma pilot is sited at Terminal 7 of the Port of Port Angeles on the Olympic Peninsula, strategically positioned on the Strait of Juan de Fuca.

This initiative is classified as a “temporary pilot-scale marine carbon dioxide removal” project. It has been designed to remove and store up to 250 tons of carbon annually. While this capacity is modest, the project’s primary goal is not volume but operational learning. Ebb Carbon views Project Macoma as an essential “learning pilot — setting the foundation on which we will scale our technology to the point where it can remove gigatons of CO₂”. The short-term demonstration is currently expected to run until approximately spring 2026.

3.3. Ancillary operational requirements and rapid de-risking

The progression of Ebb Carbon’s operational capability indicates an accelerated de-risking timeline uncommon for novel climate technologies. The company moved rapidly from a 100-ton/year demonstration-scale unit deployed at PNNL-Sequim to the 250-ton/year Project Macoma pilot, while simultaneously navigating and overcoming complex regulatory hurdles. This trajectory implies high confidence in the fundamental safety and performance of the core electrochemical system components. By completing rigorous testing with federal partners, Ebb secured external validation, enabling a rapid transition from Technology Readiness Level (TRL) 6/7 (system demonstration) to TRL 8 (first-of-a-kind commercial operation). This accelerated maturity allows the company to dedicate capital and resources predominantly toward the OpEx optimization required for meeting the below $100 per ton of CO₂ cost goal.

Operationally, the Project Macoma facility is subject to stringent environmental controls beyond the NPDES permit. Project Macoma, LLC, must adhere to the Port’s Storm Water Pollution Prevention Plan (SWPPP) and is required to develop, maintain, and implement a rigorous chemical management plan. This plan includes specific procedures governing procurement, delivery, storage, inventory, spill prevention, emergency response, and disposal, underscoring the necessary caution and stringent environmental oversight required for mCDR deployment, even at a pilot scale.

The table below provides an operational scaling profile from PNNL Precursor to Macoma Pilot: