Ocean-Based
Carbon Dioxide Removal

ASSESSMENT OF STRATEGIES

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The ocean covers 70% of the Earth’s surface and provides much of the global capacity for natural carbon sequestration. It currently holds roughly 50 times as much inorganic carbon as the preindustrial atmosphere.


The ocean’s natural capacity to store carbon could be enhanced with strategies that act to remove CO2 from the atmosphere and upper ocean and store it in ocean reservoirs, such as marine plants and geologic, or geological formations for some period of time.

A Research Strategy for Ocean-Based Carbon Dioxide Removal and Sequestration (2021) develops a research agenda to assess the benefits, risks, and potential for responsible scale up of six specific ecosystem-based and technological ocean-based CDR approaches.

A Framework for Ocean-based CDR

Ocean-based carbon dioxide removal (CDR), should be researched responsibly with climate justice and the precautionary principle in mind to determine whether ocean-based CDR can help to meet, in a timely way, global climate goals. It is important that any research done does not cause unintended and potentially irreversible harm to natural systems and coastal communities. Before understanding the role of any ocean-based CDR approach as part of a climate-mitigation strategy, there are several cross-cutting foundational issues that need to be addressed such as legal, regulatory, and governance issues, social dimensions and justice considerations, monitoring and verification of carbon removal, and economic and funding considerations. Development of a Code of Conduct for research and a governance framework should precede any ocean-based CDR deployment.

Approaches Considered

The report assessed six carbon dioxide removal (CDR) and sequestration strategies conducted in coastal and open ocean waters. Each approach was evaluated based on its existing knowledge base, potential efficacy, durability, scale, project costs, monitoring and verification, viability and barriers, and governance and social dimensions.

Click on the image to see the results

View this table to compare the six ocean CDR technologies.

OCEAN CDR RESEARCH PRIORITIES

At present, society and policymakers lack sufficient knowledge to fully evaluate ocean CDR outcomes and weigh the trade-offs with other climate response approaches, and with environmental and sustainable development goals. A research program should be implemented to address current knowledge gaps. The best approach will involve a diversified research investment strategy that includes both cross-cutting, common components and coordination across multiple individual CDR approaches in parallel.

Amongst the biotic approaches, research on ocean iron fertilization and seaweed cultivation offer the greatest opportunities for evaluating the viability of possible biotic ocean CDR approaches; research on the potential CO2 removal and sequestration permanence for ecosystem recovery would also be beneficial in the context of ongoing marine conservation efforts.

Amongst the abiotic approaches, research on ocean alkalinity enhancement, including electrochemical alkalinity enhancement, have priority over electrochemical approaches that only seek to achieve carbon dioxide removal from seawater (also known as carbon dioxide stripping).

Cross-Cutting Research Priorities

 

Estimated Budget

Duration (yr)

Total

Model international governance framework for ocean CDR research

$2-3M/yr

2-4yrs

$4-12M

Application of domestic laws to ocean CDR research

$1M/yr

1-2yrs

$1-2M

Assessment of need for domestic legal framework specific to ocean CDR


Development of domestic legal framework specific to ocean CDR 

$1M/yr

2-4yrs

$2-4M

Mixed-methods, multi-sited research to understand community priorities and assessment of benefits and risks for ocean CDR as a strategy

$5M/yr

 4yrs

 $20M

Interactions and tradeoffs between ocean CDR, terrestrial CDR, adaptation, and mitigation, including the potential of mitigation deterrence

$2M/yr

 4yrs

 $8M

Cross-sectoral research analyzing food system, energy, Sustainable Development Goals, and other systems in their interaction with ocean CDR approaches

$1M/yr

4yrs

$4M

Capacity-building research fellowship for diverse early-career scholars in ocean CDR

$1.5M/yr

2yrs

$3M

Transparent, publicly accessible system for monitoring impacts from projects

$0.25M/yr

4yrs

$1M

Research on how user communities (companies buying and selling CDR, NGOs, practitioners, policymakers) view and use monitoring data, including certification

$0.5M/yr

4yrs

$2M

Analysis of policy mechanisms and innovation pathways, including on the economics of scale up

$1-2M/yr

2yrs

$2-4M

Development of standardized environmental monitoring and carbon accounting methods for ocean CDR 

$0.2M/yr

3yrs

$0.6M

Development of a coordinated research infrastructure to promote transparent research

$2M/yr

3-4yrs

$6-8M

Development of a publicly accessible data management strategy for ocean CDR research

$2-3M/yr

2yrs

$4-6M 

Development of a coordinated plan for science communication and public engagement of ocean CDR research in the context of decarbonization and climate response

$5M/yr

10yrs

$50M

Development of a Common Code of Conduct for ocean CDR research

$1M/yr

2yrs

$2M

Total Estimated Research Budget
(Assumes all 6 CDR approaches moving ahead)

~$30M/yr

2-10 yrs

~$125M

Research Needed to Advance Ocean CDR Approaches

 

Estimated Budget

Duration (yr)

Total Budget

Carbon sequestration delivery and bioavailability

$5M/yr

5yrs

~$25M

Tracking carbon sequestration

$3M/yr

`5yrs

~$15M

In field experiments- >100 tons Fe
  and >1000 km^2 initial patch size followed over annual cycles

$25M/yr

10yrs

~$250M

Monitoring carbon and ecological shifts

$10M/yr

10yrs

~$100M

Experimental planning and extrapolation to
  global scales

$5M/yr

10yrs

~$50M

Total Estimated Research Budget 

$48M/yr

5-10 yrs

$445M

Estimated Budget of Research Priorities

$33M/yr

5-10 yrs

$290M

 

Estimated Budget

Duration (yr)

Total Budget

Technological readiness: Limited and controlled open ocean trials to determine durability and operability of artificial upwelling technologies 
(~ 100 pumps tested in various conditions)

$5M/yr

5yrs

$25M

Feasibility Studies

$1M/yr

1yr

$1M

Tracking carbon sequestration

$3M/yr

5yrs

$15M 

Modeling of carbon sequestration based upon achievable upwelling velocities and known stoichiometry of deep water sources. Parallel mesocosm and laboratory experiments to assess potential biological responses to deep water of varying sources 

$5M/yr

5yrs

$25M   

Planning and implementation of demonstration scale in situ experimentation (> 1 year, >1000 km) in region sited based input from modeling and preliminary experiments  

$25M/yr

10yrs

$250M   

Monitoring carbon and ecological shifts

$10M/yr

10yrs

$100M 

Experimental planning and extrapolation to global scales (early for planning and later for impact assessments)

$5M/yr

10yrs

$50M

Total Estimated Research Budget

~$53/yr

5-10 yrs

$466M

Estimated Budget of Research Priorities

$5M/yr

5-10 yrs

$25M

 

Estimated Budget

Duration (yr)

Total Budget

Technologies for efficient large-scale farming and harvesting of seaweed biomass

$15M/yr

10yrs

$150 M
(based on present MARINER funding levels)

Engineering studies focused on the conveying of harvested biomass to durable oceanic reservoir with minimal losses of   carbon 

$2M/yr

10yrs

$20 M

Assessment of long-term fates of seaweed biomass & byproducts

$5M/yr

5yrs

$25M

Implement & deploy a demonstration-scale seaweed cultivation & sequestration system

$10M/yr

10yrs

$100M

Validate & monitor the CDR performance of a
  demonstration-scale seaweed cultivation & sequestration system

$5M/yr

10yrs

$50M

Evaluate the environmental impacts of large-scale seaweed farming and sequestration

$4M/yr

10yrs 

$40M

Total Estimated Research Budget

$41M/yr

5-10 yrs

$385M

Estimated Budget of Research Priorities

$26M/yr

5 years

$235M

 

Estimated Budget

Duration (yr)

Total Budget

Restoration ecology and carbon

$8M/yr

5yrs

$40M 

Marine protected areas: Do ecosystem-level protection and restoration scale for marine CDR?

$8M/yr

10yrs

 $80M

Macroalgae: Carbon measurements, global range, and levers of protection

$5M/yr

10yrs

 $50M

Benthic communities: disturbance and restoration

$5M/yr

5yrs

 $25M

Marine animals and CO2 removal

$5M/yr

10yrs

 $50M

Animal nutrient-cycling 

$5M/yr

5yrs

 $25M

Commercial fisheries and marine carbon

$5M/yr

5yrs

 $25M

Total Estimated Research Budget

$41M/yr

5-10 yrs

$295M

Estimated Budget of Research Priorities

$26M/yr

5-10 yrs

$220M

 

Estimated Budget

Duration (yr)

Total Budget

Research and development to explore and improve the technical feasibility/and readiness level of ocean alkalinity enhancement approaches (including the development of pilot scale facilities)

$10M/yr

5yrs

$50M

Laboratory and mesocosm experiments to explore impacts on physiology and functionality of organisms/communities

$10M/yr

5yrs

$50M

Field experiments

$15M/yr

5-10yrs

$75-150 M

Research into the development of appropriate monitoring and accounting schemes, covering CDR potential and possible side effects.    

$10

5-10yrs

$50-100 M

Total Estimated Research Budget

$45M/yr

5-10 yrs

$180-350M

Estimated Budget of Research Priorities

$25M/yr

5-10 yrs

$125-200M

 

Estimated Budget

Duration (yr)

Total Budget

Demonstration projects including CDR verification and environmental monitoring

$30M/yr

5yrs

$150M

Development and assessment of novel electrode materials

$10M/yr

5yrs

$50M

Assessment of environmental impact and acid management strategies

$7.5M/yr

10yrs

$75M

Coupling whole rock dissolution to electrochemical reactors and systems

$7.5M/yr

10yrs

$75M

Development of hybrid approaches

$7.5M/yr

10yrs

$75M

Resource mapping and pathway assessment

$10M/yr

5yrs

$50M

Total Estimated Research Budget

$72.5M/yr

5-10 yrs

$475M

Estimated Budget of Research Priorities

$55M/yr

5-10 yrs

$350M

Resources