ICRLP Co-Director Dr. Wil Burns Explores Ocean Alkalinization’s Potential

ICRLP Co-director Wil Burns and co-author Charles R. Corbett recently published an important article in One Earth titled “Antacids for the Sea? Artificial Ocean Alkalinization and Climate Change.” This important article explores ways in which artificial ocean alkalinization (AOA) could serve as an important component of a large-scale carbon removal strategy. It includes an analysis of the risks and benefits of AOA, as well as governance considerations. 

Despite the world community coming together in 2015 and signing the Paris agreement, it has since become clear that the reality of meeting the 2.0/1.5°C temperature targets are becoming increasingly unrealistic, as countries continue to lag on meeting even the already lackluster pledges they have made. Furthermore, 87% of the scenarios run in the IPCC Fifth Assessment Report that meets the Paris Agreements targets incorporate large-scale adoption of carbon dioxide removal strategies.

Thus far, the majority of the focus on carbon dioxide removal (CDR) has been on terrestrially based technologies such as bioenergy and carbon capture (BECCS), afforestation and reforestation, and direct air capture. Although these are all methods deserving of consideration and assessment, there are also many associated shortfalls and risks, providing a compelling rationale for assessing the potential role of ocean-based carbon removal approaches. 

Ocean-based approaches to CDR are under-developed, under-funded, and under-tested. This is despite the fact that the ocean comprises 71% of Earth’s surface and is already passively absorbing 10 gigatons of carbon every year, with the great potential to store more. In light of the climate crisis, this potential is something the global community cannot afford to overlook.

Thus far, most of the ocean-based CDR has focused on ocean iron fertilization (OIF). However, recent research has concluded that OIF’s sequestration potential may be low, and it could pose serious risks to ocean ecosystems. As a consequence, it has largely been abandoned as the most viable ocean-based CDR method.  

 However, despite the shortcomings of OIF, the method does provide some incentive to look into other ocean-based methods of CDR. AOA may provide some of the greatest potentials in that regard. 

AOA is the method of adding alkalinity to ocean systems, increasing pH levels, which in turn leads to greater carbon absorption and a reduction in acidification. AOA has the potential to represent meaningful contributions to the battle against climate change and carbon sequestration, even at the low end of its potential. Several methods have been proposed:

  • Addition of powdered olivine (highly reactive lime)
  • Addition of calcium hydroxide, produced by the calcination of limestone, applied to ocean surfaces or into deep currents that end in upwelling regions
  • Utilization of local marine energy sources to manufacture alkalinity
  • Combining waste CO2 with minerals for reaction, which result in dissolved alkaline material, and pumping it into the ocean

AOA also has the added benefit of potentially combating another detrimental side effect of climate change: ocean acidification. Acidification of the ocean:

  • Reduces levels of carbonate, compromising the formation of calcium carbonate shells among coral, bivalve, and crustaceans
  • Harms finfish species, which has a detrimental impact on habitat, food source and larval survival

Ocean Acidification has increased 30% since the beginning stages of our current anthropogenic CO2 emissions, and pH levels are the lowest they have been in 2 million years.

However, AOA is not without its own potential risks, including:

  • Inhibiting photosynthesis in phytoplankton communities;
  • Threatening species that may not be able to easily adjust to increasing levels of alkalinity;
  • Introducing new and heavy toxic materials to ocean ecosystems

When facing both the uncertainties and the potential benefits of AOA deployment, good governance is critical. It enables the facilitation of research by providing clear guidelines and assessment protocols. Additionally, it identifies risks, creates rules and guidelines, and enforces them. Lastly. it provides the research legitimacy by establishing responsibility and helping to build societal support.

The provision of guidelines and structure around the international laws pertaining to oceans is also another important component of AOA implementation. Coastal countries have sovereignty over bodies of water within 12 nautical miles of their shore, and AOA would need to comply with the national permitting process of each nation. When the practice expands into a country’s exclusive economic zone (EEZ), which is the area about 200 nautical miles from the coast, things begin to get more complicated. However, the coastal country still has the authority to regulate activities that affect the marine ecosystem, so research protocols should remain similar to those being conducted in the waters just beyond the territory. Beyond the EEZ, AOA research would be permitted, but subject to principles of state responsibility should harm occur to the interests of other States under the UN Convention on the Law of the Sea. Moreover, principles of the Biodiversity Beyond National Jurisdiction, an agreement being developed under the Convention on the Law of the Sea, could be apposite, including the requirement that the parties establish conservation areas and environmental assessments pertaining to the marine biological diversity of areas beyond their national jurisdiction.

In order to ensure that a standard of compliance with acceptable environmental standards is set, looking at this matter with regard to OIF is a good starting point. In 2013 the London Protocol passed an amendment prohibiting ocean iron fertilization scientific research without a national permit and engagement in a stringent risk-assessment procedure.

Despite its potential AOA still comes with uncertainty around potential risks, questions about who has control over deployment decisions, and who bears the burden of liability. Local AOA treatments could serve as a good starting point for a gradual understanding of its impacts, and a means to allow government structures to mature alongside advances in technical understanding.

The Potential of Carbon Capture and Sequestration in the Northeast and Mid-Atlantic regions

The International Panel on Climate Change cites the widespread deployment of carbon capture and sequestration (CCS), bioenergy, and/or their combination (BECCS) as critical to the effort to limit 21st century warming due to CO2 release. The removal of CO2 from industrial effluent streams and storage in geological formations (CCS), is an established mitigation strategy that has the potential to decrease the rate at which CO2 is emitted into the atmosphere. More importantly, it is a technology that can progress towards achieving negative emissions through coupling CCS with CO2 capture from electricity generation processes driven by the combustion of biomass (BECCS). BECCS is particularly appealing because it addresses how electricity could be produced in a carbon negative future.

In “Total Cost of Carbon Capture and Storage Implemented at a Regional Scale: Northeastern and Midwestern United States” (Schmetz, Hochman & Miller, 2020), the authors show that CO2 emissions may be stored at the Northeast and Mid-Atlantic regions of the US at $52 per ton, sourced from coal-fired plants and stored onshore in depleted oil and gas fields, and that the region also has the opportunities to store CO2 in onshore saline reservoirs for less than $60 per ton. Offshore storage is also an option, where the lowest total costs of CCS with storage in offshore saline reservoirs are just over $60 per ton. Storage offshore carries less risk and inconvenience and less potential for interference from populations than onshore storage. Offshore storage could also be required if formation pressures pose geological risk issues when injecting gigatons of supercritical CO2 into onshore formations. Emissions from natural-gas-fired plants are more expensive to capture per ton of CO2, making the lowest total costs over $80 per ton. This analysis suggests that a relatively small (15%) reduction in the total cost of CCS, would make CCS economically viable at a large-scale (~8 Gt CO2 over 30 years). Large-scale carbon storage may be additionally justified when coupled with BECCS technology. Similarly, demonstrating the feasibility of CCS could ultimately facilitate a pathway to BECCS.

Enacted in 2018 by the 115th United States Congress, the Section 45Q tax credits allot $50 per ton CO2 in tax credits for the permanent sequestration of CO2 in saline geological formations, as well as $35 per ton CO2 for EOR applications of CCS. To this end, the difference between representative total costs of CCS in the northeastern and midwestern United States and the threshold for profit motivated adoption is relatively small with the Section 45Q credits. With some technological improvement, adoption of CCS on a meaningful scale is possible in this region. With EOR and 45Q, CCS is viable, and has been undertaken on commercial scales at the Petra Nova-WA Parish Generating Station in Texas and the Boundary Dam plant in Canada. CO2 captured at both of these locations is transported to nearby oil fields and sold to enhance recovery. Governments can and should support these initiatives as sound environmental policy, like the U.S. and Canadian federal governments did for Petra Nova and Boundary Dam, providing $190 million and $240 million for those projects, respectively. Grant funding supporting the construction of commercial scale CCS projects, like the $190 million DOE supplied for the Petra Nova plant, incentivize first-of-a-kind construction that allows for learning, feasibility testing, and risk reduction for future commercial implementations. The 45Q tax credit incentive is a promising environmental policy initiative that encourages the adoption of CCS, the reduction of its cost over time because of learning-by-doing and could ultimately result in reduction of CO2 in the atmosphere.

 Considering the risk and long-term planning and capital commitment associated with constructing or renovating electricity generating infrastructure to serve CCS, the initiative to incentivize early CCS applications should also be coupled with a long-term commitment to the section 45Q credits. If the political support for CCS and the section 45Q credits appears fragile or short-lived, the potential repeal or expiration of these credits will become a hazard that adds to the risk prospective CCS adopters will need to account for. This short-term commitment coupled with the energy infrastructure risk paradigm could nullify the incentives for adoption of carbon capture technology that the Section 45Q tax credits were written to provide.

While the establishment of CCS must precede full-scale implementation of BECCS from a logical/technological perspective, concurrent pilot projects that demonstrate the feasibility of BECCS would represent significant advances. One such opportunity for CCS and BECCS could come in the form of power plants that are facing pressure to refuel or repower with more environmentally sound technology, such as the to-be-shuttered coal-fired B.L. England Generating Station in southern New Jersey. The plant was scheduled for a conversion to natural gas, but successful opposition to a pipeline link resulted in the cancellation of the project. A conversion to biomass, perhaps co-firing with coal, coupled with carbon capture could presumably ameliorate the environmental concerns that comprised the original basis for shuttering the plant. Additionally, this plant, and other legacy coal-fired locations, is served by a railroad infrastructure that would make transporting biomaterials to the plant for co-firing with coal a simple transition that does not require traversing the complexities of constructing new pipeline. This particular location, as well as a couple others on the U.S. East Coast, is well-suited for carbon storage with reservoirs available both below the power-plant and in nearby regions offshore that would encounter less citizen opposition. A project of this nature could represent an example of a catalytic “tangible, near-term success” for CCS, biomass, and/or BECCS. Application of BECCS technology in a state like New Jersey that lacks an oil and gas culture and history and is strongly opposed to further industrialization including pipelines might provide a viable test for addressing concerns about BECCS and aid in the transformation from coal to renewable, carbon negative BECCS technology.


Schmelz, William J., Gal Hochman, and Kenneth G. Miller. “Total cost of carbon capture and storage implemented at a regional scale: northeastern and midwestern United States.” Interface Focus 10.5 (2020): https://doi.org/10.1098/rsfs.2019.0065


A critical overview of solar assisted carbon capture systems: Is solar always the solution?

Mohammad Saghafifar, Samuel Gabra                                                                  International Journal of Greenhouse Gas Control, 2020

This paper focuses on possible integration schemes between solar thermal collectors and carbon capture systems. In its entirety, solar assisted carbon capture systems can be categorized into direct and indirect systems. Key factor in designing solar assisted carbon capture systems
is to match the thermal-grade between the collector and gas separation process.

For post-combustion systems, in particular, amine based systems have been widely considered for integration with solar thermal collectors using either direct or indirect schemes. Comparing direct and indirect integration schemes, results are overwhelmingly in favour of indirect solar integrations. The key merits of indirect integration include its additional flexibility in system operation and the high solar energy utilization factor it offers. For direct systems, solar thermal energy utilization is limited to the reboiler heat duty. Moreover, higher temperature concentrating solar thermal collectors with higher optical efficiencies can be used in indirect systems. These conclusions can be extended to the case of using any other low temperature gas separation technique including other chemical absorption and chemical/physical temperature swing adsorption. Direct integration may only be suitable when high grade heat is required for gas separation, as in calcium looping.

For pre-combustion systems, all the available studies focused on utilizing solar thermal energy for fuel reforming/gasification stage. It is more feasible to supply the H2/CO2 separation energy from other low-grade sources. The advantage of these systems is the inherent ability of storing solar energy chemically in form of the upgraded fuel. In addition, high-grade heat needed for reforming/gasification stage makes solar assisted systems more feasible.

For oxyfuel combustion, both direct and indirect schemes were studied. In direct systems, solar energy is used to derive an endothermic reduction reaction for chemical looping processes. Solar hybrid chemical looping systems have two advantages: first, the inherent carbon dioxide sequestration and second, storing solar thermal energy both chemically and sensibly. For indirect systems, solar energy is utilized within the power cycles whilst air separation systems were used for pure oxygen production. In terms of merits, these systems are similar to indirect systems using low temperature gas separation methods. Possible future research direction for solar assisted carbon capture systems can be classified into solar collectors cost reduction research and innovative integration scheme research. Firstly, the cost of collectors, irrespective of technology, must be reduced. In addition, more research must be carried out on high temperature solar collector integration within high-temperature carbon capture and storage (CCS) systems. For post-combustion systems, ongoing research on solar assisted calcium looping systems is promising. Integrating high-grade solar energy for fuel reforming and gasification in pre-combustion CCS is another potential research route.

An interesting aspect of solar assisted CCS systems is the possibility of its utilization as an energy storage scheme coupled with CO2 capture. In these schemes, extra available solar energy during high insolation periods is employed to further run the endothermic part of the CCS
process and store the product for usage during instances of low solar insolation. The products from these processes can be simply stored.

Integrated assessment modeling of carbon removal at ICRLP

Authored by David Morrow, Director of Research, Institute for Carbon Removal Law and Policy

Bioenergy with carbon capture and storage (BECCS) is sometimes described as the only technology ever invented by modelers. There’s a grain of truth to this: the idea of combining bioenergy with CCS to produce a negative emissions technology rose to prominence because of its adoption by integrated assessment modelers in the early 2000s. Since then, these models have provided one important tool for thinking about how carbon removal might play a role in climate policy. The Institute for Carbon Removal Law and Policy is helping to push the boundaries of integrated assessment modeling of carbon removal with two ongoing projects.

What are integrated assessment models?

Before we get to ICRLP’s modeling projects, let’s back up a bit. What are integrated assessment models (IAMs)? Basically, IAMs are computer models that combine a model of the climate system with models of the economy, the energy sector, and land use to help researchers think rigorously about possible climate futures. For instance, researchers can use these models to ask questions like, “What would happen to the energy sector and the climate if coal were phased out worldwide by 2050?” or, “How would the energy sector change over time if the whole world put a gradually rising price on carbon beginning in 2040?” Researchers can also use these models to identify decarbonization pathways by which the world could meet various climate policy goals, such as the Paris Agreement’s goal of limiting global warming “well below 2°C.” When you read headlines saying that the world needs to cut its emissions in half by 2030 in order to limit global warming to 1.5°C, you’re reading a conclusion based in large part on integrated assessment modeling.

CarbonBrief offers an excellent introduction to IAMs and their role in studying climate policy. If you prefer to learn by doing, check out Climate Interactive’s EnROADS model, an IAM that’s fast enough to run in your web browser.

How are IAMs used to study carbon removal?

Integrated assessment modelers realized almost twenty years ago that they could combine two technologies that were already represented in their models—bioenergy and CCS—to model a technology that actively removes carbon dioxide from the atmosphere. Research over the past two decades suggests that developing and scaling negative emissions technologies makes it much likely that the world can keep warming below 2°C or 1.5°C. In fact, modeling studies suggest that unless the world reduces its greenhouse gas emissions extremely rapidly over the next two or three decades, it may not be possible to limit warming below 1.5C without large-scale carbon removal

Until recently, however, few integrated assessment modelers had incorporated any kind of carbon removal into their model besides BECCS and reforestation. (For some notable exceptions, see recent papers led by Jessica Strefler, Giulia Realmonte, and Jay Fuhrman.) As a result, BECCS has long operated as a kind of stand-in for the wide variety of approaches to carbon removal that have been proposed. Actually implementing BECCS at the scales projected in many IAM scenarios would likely be disastrous because it would require devoting such vast tracts of land to bioenergy. Overcoming the conceptual and technical hurdles to modeling other approaches to carbon removal would be an important step in understanding what role carbon removal can realistically play in just and sustainable climate policy.

Integrated assessment modeling at ICRLP

Earlier this year, ICRLP launched a project to produce a variant of the Global Change Analysis Model (GCAM), a major IAM developed by the Joint Global Change Research Institute. I’m working with Postdoctoral Researcher Raphael Apeaning to extend GCAM’s ability to model carbon removal. That involves both incorporating additional approaches to carbon removal, starting with direct air capture, enhanced weathering, ocean alkalinization, and soil carbon sequestration; and giving GCAM the capacity to model various policies for incentivizing and supporting carbon removal. We gratefully acknowledge the financial support of the Alfred P. Sloan Foundation for this project.

I’m also supervising an undergraduate in American University’s School of International Service, Garrett Guard, as he uses GCAM to write his senior thesis on the role of BECCS in climate policy. His thesis grew out of a research project he did for a course I taught last year on using integrated assessment models for climate policy analysis. Garrett’s research looks at what happens when the world tries to meet various climate targets if we exclude fossil fuel CCS, BECCS, or both from the climate policy portfolio, as well as how that varies across different socioeconomic pathways.