Demystifying Ocean Carbon Dioxide Removal

The Environmental and Energy Study Institute (EESI) and the World Resources Institute (WRI) held a briefing about ocean carbon dioxide removal (CDR). Reaching global climate goals will require not only deep and rapid reductions in greenhouse gas emissions, but also large-scale removal of excess carbon dioxide from the atmosphere. While federal funding for research, development, and demonstration of land-based CDR approaches and technologies has increased significantly in recent years, the ocean also presents opportunities for carbon removal.

The ocean covers 70% of the Earth and serves as its largest carbon sink, holding 42 times the carbon in the atmosphere. Ocean CDR—the practice of removing and storing carbon from the ocean—is garnering increasing scientific, governmental, and private sector interest. At the same time it presents uncertainties related to efficacy, ecosystem impacts, and governance, which decision-makers must understand in order to determine if and how the practice could be scaled up as a climate solution.

Panelists discussed the current state of ocean CDR, including the status of different approaches; the policy and regulatory landscape; research gaps; and the importance of responsible scaling. They also discussed how lawmakers can engage in this emerging policy arena to meet mitigation and adaptation goals.

Highlights

KEY TAKEAWAYS

Carbon dioxide removal (CDR) refers to the approaches and technologies that extract carbon dioxide from the environment and sequester it for climate-relevant periods of time.
Leveraging the ocean can help diversify the range of CDR approaches available. Ocean CDR approaches fall into two general categories: biotic approaches, which rely on biology and photosynthesis, and abiotic approaches, which do not.
Ocean CDR should have six qualities: measurable, verifiable, permanent, additional, energy efficient, and credible.
A research code of conduct for ocean CDR would establish shared norms, best practices, and encourage responsible research among the public and private sectors.
The Biden-Harris Administration released the Ocean Climate Action Plan in March 2023. Ocean CDR is a key action mentioned in the plan, and the National Oceanic and Atmospheric Administration is the lead agency responsible for the majority of the outlined work.

Rep. Chellie Pingree, U.S. Representative (D-Maine)

According to the Intergovernmental Panel on Climate Change, atmospheric carbon dioxide concentrations are currently higher than at any time in the last two million years. About 30% of the carbon dioxide released into the atmosphere is absorbed by the ocean.
Policymakers must make additional investments in ocean carbon dioxide removal (CDR), specifically investments in ocean CDR research.
Maine has invested in ocean CDR by implementing an ocean monitoring and data collection program and exploring the ability of seaweed and kelp to lower acidity in the ocean and to sequester carbon.
The Inflation Reduction Act of 2022 (IRA) (P.L. 117-169) supports ocean CDR with investments for climate change mitigation research. The National Oceanic and Atmospheric Administration (NOAA) and Department of Energy (DOE) are advancing projects focused on researching and developing ocean CDR technologies.
Decreasing greenhouse gas emissions is the most effective way to address climate change impacts, but research and investment in ocean CDR can complement those efforts.

Katie Lebling, Associate II, Carbon Removal and Industrial Decarbonization, World Resources Institute (WRI)

CDR refers to the approaches and technologies that extract carbon dioxide from the air and sequester it for climate-relevant periods of time. This contrasts with carbon capture and storage technologies, which capture carbon dioxide emissions directly at the emission source.
There is so much carbon dioxide in the atmosphere that even if all emissions were stopped today, CDR would be necessary to bring carbon dioxide concentrations down to safer levels.
CDR takes carbon dioxide directly out of the air. Because the ocean absorbs carbon dioxide from the atmosphere, ocean CDR indirectly removes carbon dioxide from the atmosphere via the ocean. CDR can help counterbalance the emissions that are the most difficult to avoid. CDR is not a substitute for reducing greenhouse gas emissions and cannot be an excuse to delay emission reductions.
Each CDR approach and technology has different benefits, risks, and circumstances of its application.
DOE has heavily invested in direct air capture and other novel approaches to CDR, but less funding has gone to the research and development of ocean CDR.
The ocean, which covers 70% of the Earth, is good at absorbing and sequestering carbon. The ocean is already the Earth’s largest carbon sink, holding 42 times the amount of carbon dioxide that is in the atmosphere and absorbing 25% of human-caused carbon dioxide emissions each year. Leveraging the ocean can help diversify the range of CDR approaches, which would balance the risks and benefits of each approach and reduce the pressure on land-based CDR approaches.
One way to categorize ocean CDR approaches is to differentiate between biotic and abiotic approaches. Biotic approaches rely on biology or photosynthesis and abiotic approaches do not.
Seaweed cultivation is a biotic ocean CDR approach. As the seaweed grows, it absorbs carbon dioxide dissolved in the ocean’s surface waters. Next, the seaweed is harvested and sunk to the deep ocean for sequestration. This process depletes ocean surface waters of carbon dioxide, allowing the ocean to absorb more carbon dioxide from the atmosphere.
Ongoing research on seaweed cultivation is focused on optimizing cultivation and harvesting methods and improving methodologies to measure carbon dioxide sequestration, which will provide a better understanding of the permanence of this CDR approach. DOE’s Advanced Research Projects Agency-Energy (ARPA-E) supports research on macro algae and seaweed cultivation.
Ocean alkalinity enhancement is an abiotic ocean CDR approach. This involves distributing alkaline materials (such as ground-up rocks) into the ocean, which react with the dissolved carbon dioxide to form carbonates and bicarbonates that trap carbon dioxide. This can be beneficial to reduce ocean acidification in a particular area, but could also introduce harmful trace minerals to an ecosystem. The impacts of mining and transporting the rocks is also a consideration. It is challenging to measure, report, and verify carbon sequestration amounts with this approach. The Pacific Northwest National Laboratory is researching ocean alkalinity enhancement as an ocean CDR approach.
Oceans are interconnected and moving, so ocean CDR impacts are not contained in one area. This makes ocean CDR difficult and expensive to measure, report, and verify.
The existing governance and regulation of ocean CDR poses challenges because existing domestic and international regulatory frameworks were written for terrestrial CDR and retroactively applied to ocean CDR.
Ocean CDR could potentially provide multi-gigaton-scale removal of carbon dioxide in future decades. A National Academies assessment points out the potential for large-scale ocean CDR, but also mentions uncertainty around estimates.
Ocean CDR can have non-carbon benefits like reducing ocean acidification, replenishing ecosystems, and providing jobs. Increased funding and permitting to enable research will help clarify the uncertainties associated with ocean CDR.

Savita Bowman, Senior Program Manager, Carbon Management, ClearPath

Congressional appropriations for fiscal year (FY) 2024 provided increased support for ocean CDR. NOAA was allocated $2 million to assess blue carbon, including carbon sequestration by biomass like seaweed and mangroves. The National Oceanographic Partnership Program received $500,000 for cross-agency collaboration on ocean CDR technologies.
DOE’s Office of Fossil Energy and Carbon Management received $250,000 to clarify regulatory processes for ocean CDR and $10 million for research, development, and demonstration of biotic ocean CDR.
FY 2023 appropriations also included resources for ocean CDR through investments in the National Science Foundation (NSF), National Institute of Standards and Technology, NOAA, Bureau of Ocean Energy Management, National Oceanographic Partnership Program, and DOE Office of Fossil Energy and Carbon Management.
Federal investment in ocean CDR innovation, technology, and research is generally newer than investment in land-based CDR. Before FY 2021, very few resources were allocated to ocean CDR.
Policies starting with the Energy Act of 2020 (P.L. 116-260) began to look at CDR more broadly by setting up a CDR taskforce and report. Both the Infrastructure Investment and Jobs Act (P.L. 117-58) and the Chips and Science Act (P.L. 117-167) included language specifically focused on ocean CDR.
The REMOVE Act (H.R.8013) was a bipartisan bill proposed during the 117th Congress that would have helped federal agencies relevant to ocean CDR coordinate on deploying CDR technologies.
The CREST Act of 2023 (S.1576) is a proposed bipartisan bill that would provide resources for research and development on ocean CDR. This bill also includes an advanced market commitment to demonstrate demand which, in turn, encourages innovation.
The Ocean Restoration Research and Development Act (H.R.7797) is a proposed bill that would set up a pilot program to facilitate research on ocean restoration, carbon dioxide removal, and carbon storage.
Federal policies, along with a clear regulatory framework and research, can help the United States lead in the ocean CDR sector. Financial incentives can help alleviate industry uncertainties.
Permitting clarity is crucial to the growth of ocean CDR. Existing permitting frameworks are not specific to ocean CDR research and development considerations.

Edward Sanders, Chief Operating Officer, Equatic

Ocean CDR should have six qualities: measurable, verifiable, permanent, additional (i.e., carbon would not have been removed otherwise), energy efficient, and credible. It must also be affordable and without negative environmental impacts.
Equatic produces green hydrogen while removing carbon dioxide using the ocean. The company was developed with support from DOE.
Equatic uses electrolysis and direct air contact to capture carbon dioxide from the ocean and atmosphere. The company stores the carbon dioxide in calcium carbonate solids and dissolved bicarbonate ions where it can stay for between 10,000 to one billion years. This allows for efficient, permanent, and planetary-scale carbon dioxide removal.
This method does not need carbon dioxide storage or transportation and does not have the risks associated with CDR gases, as the calcium carbonate solids and dissolved bicarbonate ions stay in the ocean.
Equatic pumps seawater to its plant and measures the water’s carbon content. Then an electrical current runs through the seawater and separates the water into hydrogen gas, oxygen gas, a base, and an acid. Equatic reacts the base with carbon dioxide in the air, which results in solid calcium carbonates, and reacts the acid with rock to ensure no ocean acidification. Then, Equatic measures the carbon content of the water again, and assesses the net change in carbon content.
A 30-megawatt facility could remove one ton of carbon dioxide every five minutes while an equivalent area of open ocean would take 12 months to remove one ton of carbon dioxide.
Equatic’s two pilot plants have been operating for over one year in Los Angeles, California, and Singapore. Each plant removes 100 kilograms of carbon dioxide and produces three kilograms of green hydrogen per day.
Equatic is constructing a demonstration plant, which will be the world’s largest ocean-based CDR plant.
More efficient permitting processes require clearer timelines and more effective inter-agency collaboration, particularly between the U.S. Environmental Protection Agency (EPA), NOAA, DOE, and NSF. A pre-permitting, consultative process that allows companies to provide regulators with the planning data and objectives of plants would be beneficial for ocean CDR companies.
Ocean CDR should receive the same types of commercialization and technology support that the federal government provides to other CDR pathways. The federal government is better suited than the private sector at providing long-duration contracts for ocean CDR. Ten- to 20-year procurement programs allow Equatic to access necessary private sector funds and financing that are required to build ocean CDR plants.

Sara Wanous, Government Relations Manager, Ocean Conservancy

Many knowledge gaps exist within the field of ocean CDR, so the federal government and the ocean CDR industry need to target research supporting implementation decisions.
Establishing a research code of conduct for ocean CDR could address concerns and knowledge gaps in the industry. Research codes of conduct are common tools to create shared norms, best practices, and encourage responsible research among public and private organizations.
The Code of Conduct for Marine Carbon Dioxide Removal Research outlines the three phases of responsible research: planning, execution, and conclusions.
Congress can play a role in implementing a research code of conduct by requiring the use of a code of conduct, supporting data-sharing practices, and establishing reasonable rules around intellectual property as a caveat to funding. Funders can coordinate research within the community, including by developing joint activities and resources.
Monitoring, reporting, and verification is a challenge for ocean CDR, but it is central to accounting for CDR-mitigated greenhouse gas emissions. Through monitoring, reporting, and verification, companies determine how much carbon dioxide an ocean CDR method is removing from the carbon cycle or atmosphere.
Additionality is the increased amount of carbon that is being stored because of the implementation of CDR technology. To determine additionality, researchers measure how many additional carbon molecules are being sequestered, which requires researchers to have a good baseline of carbon dioxide levels.
Durability is how well the carbon dioxide is stored, and if carbon dioxide will return back to the atmosphere or remain in storage. Without monitoring, reporting, and verification, the additionality and durability of carbon sequestration cannot be confirmed.

Gabby Kitch, Marine Carbon Dioxide Removal Lead, Ocean Acidification Program, National Oceanic and Atmospheric Administration (NOAA)

CDR may have benefits for ocean acidification mitigation.
The Biden-Harris Administration released the Ocean Climate Action Plan in March 2023. Ocean CDR is a key action mentioned by the plan. Of the ocean CDR actions outlined in the Ocean Climate Action Plan, NOAA was the lead agency for 75% of them.
The Ocean Climate Action Plan named a Fast Track Action Committee, which brought together about 12 federal agencies to write a research plan on ocean CDR.
NOAA’s focus on science, stewardship, and service is key to its leadership on ocean CDR. NOAA has always invested in foundational climate research for monitoring greenhouse gases both in the atmosphere and the ocean, studying climate impacts on ecosystems, and modeling the climate.
In June 2023, NOAA published a CDR research strategy that addressed four different aspects of CDR research. The strategy reviews federal motivation for CDR research, reports the state of CDR science, and investigates NOAA assets that could be expanded to support ocean CDR. The strategy also sets a vision for how NOAA can support the CDR field.
NOAA has a variety of assets that can support the CDR field. NOAA’s observing networks for atmospheric and oceanic greenhouse gases and NOAA’s modeling capabilities showcase different climate projections and their associated ecosystem impacts.
NOAA’s projects focused on expanding and incorporating ocean CDR into data management, are key to supporting accountability and moving ocean CDR forward.
Ocean CDR research is necessary. NOAA’s Coral Reef Watch quantified recent coral bleaching as unprecedented, and carbon dioxide pollution in the atmosphere is causing dramatic ocean warming. Ocean CDR research has unknown risks, but, at the same time, the risks of climate change are also very present.
In FY 2023, NOAA, through the National Oceanographic Partnership Program, supported 17 ocean CDR projects with a total of $24.3 million, including $14 million in IRA funding through the Climate Resilience Accelerator Program. To receive a National Oceanographic Partnership Program grant, applicants must collaborate across sectors, which brings together federal agencies, private partners, and academic partners. This requirement means that while NOAA funded 17 projects, it collaborated with nearly 50 U.S. institutions and one Japanese collaborator.
NOAA is a co-chair of the Fast Track Action Committee and is formalizing relationships with multiple agencies on ocean CDR.
NOAA is defining the efficacy and safety of ocean CDR methods through its research portfolio and is drafting its own implementation plan.

Q&A

Q: How do we go about making decisions amidst the uncertainties surrounding ocean CDR?

Lebling

There are many different factors that impact the efficacy and uncertainty of each ocean CDR project. Amidst this uncertainty, implementers should prioritize projects that have the most certainty of working.

Bowman

Field research and development is critical to understanding how ocean CDR will work outside of a laboratory.
There is no clarity on the permitting process for different types of ocean CDR, but clarity could benefit projects.
It is crucial we know how much carbon dioxide CDR technologies are removing.

Sanders

In the face of uncertainty, inaction is seldom the right answer. What implementers do must be grounded in science and in collaboration with communities that are willing to push these projects forward.

Wanous

The scientific community agrees that the world will require CDR to reach global climate goals.
A code of conduct would ensure the necessary research and data collection would be done with the best intentions and not cause unnecessary harm.

Kitch

Fast tracking processes that are holding up ocean CDR projects from getting into the water would benefit the industry. To ensure ocean CDR research is done with little harm, greater research on environmental and ecosystem impacts is necessary.

Q: Are there any lessons we can learn from the monitoring, reporting, and verification of terrestrial CDR? Is regulating ocean CDR monitoring, reporting, and verification a role for the federal government or a third party?

Sanders

Standards for ocean CDR monitoring, reporting, and verification should be established by policymakers and third-party regulators.
Ocean CDR companies need clear monitoring, reporting, and verification because it allows the companies to establish credibility with buyers and build larger facilities.

Bowman

The DOE Office of Fossil Energy and Carbon Management’s Carbon Negative Energy Earthshot has a focus on ocean CDR monitoring, reporting, and verification.
The DOE Office of Technology Transitions posted a notice of intent, which seeks to understand what CDR monitoring, reporting, and verification looks like and what factors to consider.
A federal stamp of approval on ocean CDR monitoring, reporting, and verification would help clarify uncertainties.

Kitch

Given NOAA’s existing assets for monitoring ocean carbon dioxide and vision outlined in its CDR research strategy, NOAA seeks to act as a verifier for ocean CDR.

Wanous

Translating terrestrial CDR methods and regulations to the ocean is difficult because oceans are international, so solutions must be international as well.

Q: What can be done to move the ocean CDR industry forward?

Kitch

To benefit the ocean CDR industry, researchers should be focused on bringing projects to scale, and policymakers should create efficient pathways that allow projects to quickly test in the water.

Sanders

The technology is currently too expensive, so until prices become more competitive, scaled up projects are not as feasible.

Lebling

Commercial-scale projects require more funding.
General education about ocean CDR for the public could also benefit the industry.

Q: Is it scientifically possible to accurately measure ocean CDR and verify ocean CDR permanence?

Kitch

It is not yet possible to accurately measure ocean CDR or verify ocean CDR permanence.
ARPA-E’s Sensing Exports of Anthropogenic Carbon through Ocean Observation program focuses on different sensors that could be used for ocean CDR monitoring, reporting, and verification.
Increasing the effectiveness and availability of monitoring, reporting, and verification sensors, as ARPA-E is doing, and increasing the ability to fit sensors onto autonomous platforms will speed up the process of ocean carbon dioxide monitoring and lower monitoring, reporting, and verification costs in the long run.

Q: What are the differences between nature-based and technology-based solutions? Is there a big divide between these types of solutions?

Bowman

A technology-inclusive approach would prevent technology lock-in.
Ensuring that permitting accounts for the unique capacities of different ocean CDR approaches as they become ready would be valuable.

Kitch