The Intergovernmental Panel on Climate Change (IPCC) has emphasized that meeting the Paris Agreement’s temperature objectives will require both highly aggressive measures to decarbonize the global economy as well as large-scale initiatives to remove carbon dioxide from the atmosphere. 

One approach to scaling up the carbon removal industry is Enhanced Oil Recovery (EOR), which may be counterintuitive and contentious, but can also play a significant role in decreasing carbon emissions.

The Intergovernmental Panel on Climate Change (IPCC) has emphasized that meeting the Paris Agreement’s temperature objectives will require both highly aggressive measures to decarbonize the global economy as well as large-scale initiatives to remove carbon dioxide from the atmosphere. In 2018, the IPCC concluded that “<a href="https://www.ipcc.ch/site/assets/uploads/sites/2/2022/06/SPM_version_report_LR.pdf">all pathways that limit global warming to 1.5°C with limited or no overshoot project the use of carbon dioxide removal (CDR) on the order of 100–1000 GtCO2 over the 21st century</a>.” In some scenarios that limit global warming to 1.5°C, <a href="https://www.researchgate.net/profile/Max-Franks/publication/366399767_Pigou&#x27;s_Advice_and_Sisyphus&#x27;_Warning_Carbon_Pricing_with_Non-Permanent_Carbon-Dioxide_Removal/links/63a03cce40358f78eb015cc4/Pigous-Advice-and-Sisyphus-Warning-Carbon-Pricing-with-Non-Permanent-Carbon-Dioxide-Removal.pdf">half of current carbon emissions have to be removed annually in the second half of the 21st century</a>. Moreover, in its Sixth Assessment Report, the IPCC declared that deployment of carbon dioxide removal approaches is “<a href="https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_SPM.pdf">unavoidable</a>” if the net-zero objectives of the Paris Agreement are to be realized.
In the 2021 <a href="https://www.congress.gov/117/bills/hr3684/BILLS-117hr3684enr.pdf">Infrastructure Investment and Jobs Act</a>, the U.S. Congress allocated $3.5 billion for the development of four “<a href="https://www.energy.gov/oced/four-regional-clean-direct-air-capture-hubs">regional direct air capture hubs</a>.” <a href="https://www.iea.org/reports/direct-air-capture">Direct air capture facilities</a> can extract carbon dioxide from ambient air, with the CO2 subsequently stored in deep geological formations, or converted for use.
Currently, there are only <a href="https://www.iea.org/reports/direct-air-capture-2022">18 direct air facilities operating globally</a>, sequestering approximately 10,000 tons of CO2. However, the <a href="https://www.iea.org/reports/direct-air-capture-2022">International Energy Agency has projected</a> that we may need almost a billion tons of carbon removal from such facilities by 2050 to keep us on track to meet the objectives of the Paris Agreement. Many believe that U.S. investments in direct air capture hubs can help scale up the industry by helping to bring down the currently <a href="https://www.wri.org/insights/direct-air-capture-resource-considerations-and-costs-carbon-removal#:~:text=The%20range%20of%20costs%20for,less%20than%20%2450%2Ftonne.">imposing costs</a> of such facilities <a href="https://bipartisanpolicy.org/blog/dac-hubs/">by fostering economies of scale and learning by doing</a>, much as policy measures <a href="https://www.catf.us/2019/06/leveraging-enhanced-oil-recovery-for-large-scale-saline-storage-of-co2/">helped to drive down the cost of solar energy</a>. Government support of this nature can also drive the <a href="https://www.pnas.org/doi/epdf/10.1073/pnas.1806504115">infusion of capital into the construction of critical transport infrastructure</a> for both carbon capture projects.
In January, the U.S. Department of Energy issued a <a href="https://www.fedconnect.net/FedConnect/default.aspx?ReturnUrl=%2ffedconnect%3fdoc%3dDE-FOA-0002735%26agency%3dDOE&amp;doc=DE-FOA-0002735&amp;agency=DOE">Funding Opportunity Announcement</a> for the hubs. The Announcement detailed that direct air capture hubs could be developed for both geological storage of carbon dioxide, as well as “utilization,” which could include “storage in conjunction with hydrocarbon extraction,” a form of an operation known as “enhanced oil recovery (EOR).” CO2 EOR entails the injection of carbon dioxide into an oil reservoir that is 80-90% depleted to <a href="https://reader.elsevier.com/reader/sd/pii/S1364032112007435?token=F51C568FF16DDBE5C15361BCF7C13DAFF73F3E1ABD7E1E4855A50A82382F4E589FE2469CCFA436FD195ED44F6FFAAFB4&amp;originRegion=us-east-1&amp;originCreation=20230311221121">displace the oil with a density of less than 900 kg/m3 from the rock pores, pushing it toward production wells. It can increase the production from oil reservoirs by </a><a href="https://www.sciencedirect.com/science/article/abs/pii/S1750583617300099">5-20% over and above primary production (driven by the natural pressure of a reservoir) and tertiary recovery</a> (water injection) methods. Approximately a third of injected CO2 in the EOR process is geologically stored, with the remainder produced with oil, recaptured, and reinjected <a href="https://www.catf.us/wp-content/uploads/2018/11/CATF_Factsheet_CO2_EOR_LifeCycleAnalysis.pdf">until all of the CO2 is ultimately sequestered</a>.
CO-based EOR operations began in West Texas in the early 70s and now account for <a href="https://www.natlawreview.com/article/enhanced-oil-recovery-energy-transition">approximately four percent of U.S. oil production</a>. While North American operations predominated historically, <a href="https://www.iea.org/commentaries/whatever-happened-to-enhanced-oil-recovery">60% of such operations are now based in other countries</a>.
85% of the CO2 used in EOR operations <a href="https://www.vox.com/energy-and-environment/2019/10/2/20838646/climate-change-carbon-capture-enhanced-oil-recovery-eor">is derived from natural sources</a>, primarily a few large terrestrial reservoirs. However, the consensus is that such operations can only scale up further <a href="https://iea.blob.core.windows.net/assets/bf99f0f1-f4e2-43d8-b123-309c1af66555/Storing_CO2_through_Enhanced_Oil_Recovery.pdf">if supplemented by anthropogenic sources, most notably from carbon capture with storage or carbon dioxide removal options</a>. In turn, many proponents of EOR argue that it can play a critical role in scaling up both carbon capture with storage (CCS) and carbon dioxide removal operations <a href="https://www.frontiersin.org/articles/10.3389/fclim.2019.00005/full">by providing a critical source of revenue to incentivize such operations</a>, <a href="https://www.vox.com/energy-and-environment/2019/10/2/20838646/climate-change-carbon-capture-enhanced-oil-recovery-eor">driving down costs</a> by economies of scale, and <a href="https://www.vox.com/energy-and-environment/2019/10/2/20838646/climate-change-carbon-capture-enhanced-oil-recovery-eor">helping to foster development critical infrastructure</a>, such as pipelines to help effectuate sequestration at the gigaton level. Historically, CO2-EOR has, by far, used more captured CO2 than any other industrial process, and is the only commercially established carbon utilization option that provides large-scale permanent storage for captured CO2. However, a number of commentators have expressed consternation about the prospects of a role for enhanced oil recovery in the nascent carbon dioxide removal industry. For example, the non-governmental organization, Carbon180, has argued that EOR could “<a href="https://carbon180.medium.com/a-breakdown-of-the-dac-hubs-funding-opportunity-announcement-40409db708d5">prolong … a reliance on fossil fuels</a>,” while the Energy Justice Network has contended that the process can increase carbon dioxide emissions by combustion of “<a href="https://www.energyjustice.net/coal/eor">oil that would otherwise be left in the ground</a>.”
However, I think these positions are misguided and potentially unfortunate in terms of global climate goals. Carbon180’s argument is premised on assumption that without EOR, fossil fuel use would be phased out more quickly. Yet the reality is that IPCC modeling projects that the globe <a href="https://www.wri.org/insights/co2-direct-air-capture-plant-will-help-extract-oil-texas-could-actually-be-good-climate">will still be using substantial amounts of fossil fuels in the middle of this century, even under 1.5°C scenarios</a> due to constraints in decarbonizing many sectors dependent on such resources. Moreover, meeting this demand will not be contingent on EOR, as there are currently <a href="https://www.e-education.psu.edu/egee102/node/1932">50 years’ worth of proven petroleum reserves</a> at current levels of consumption.
Also, while perhaps counterintuitive, EOR is likely to actually result in a net decrease in carbon dioxide emissions under most circumstances. Each ton of carbon dioxide injected into a well in the EOR process <a href="https://www.pnas.org/doi/epdf/10.1073/pnas.1806504115">can yield 2-3 barrels of oil production</a>, and <a href="https://www.pnas.org/doi/epdf/10.1073/pnas.1806504115">1.2 tons of carbon dioxide when this oil is burned</a>. However, the International Energy Agency (IEA) has estimated that <a href="https://www.iea.org/reports/storing-co2-through-enhanced-oil-recovery">80% of each barrel that is produced through the EOR process displaces other oil production</a>.
After taking into account all emissions associated with the process, including energy use in the EOR process and emissions associated with combusting the oil, the IEA estimates that each ton of CO2 injected in the EOR process results in CO2 abatement of 0.63-0.79 tons. Drawing upon the IEA’s lifecycle analysis, the Clean Air Task Force concluded that “a barrel of EOR oil represents 37 percent less CO2 than conventional oil.” Another recent study concluded that EOR could ultimately achieve somewhere between 4.5-8% of the reduction in carbon dioxide emissions necessary to meet the Paris Agreement’s objectives. However, these numbers must be qualified by the carbon intensity of oil supplies that EOR operations displace. For example, oil production in Venezuela has approximately twice the carbon emissions on average than U.S. operations, while emissions are about 50% higher in Iranian production. Overall, CO2 EOR generates an emissions reduction benefit even when displacing low-intensity oil. Moreover, the benefits of EOR operations can be even higher in cases where it results in the displacement of unconventional sources of oil, which can have a carbon dioxide intensity of 108-173% of conventional oil.
Additionally, because EOR operations increase the quantity of carbon dioxide that dissolves in aquifer stores, it would <a href="https://royalsocietypublishing.org/doi/epdf/10.1098/rsta.2016.0447">facilitate more secure storage</a> than standard geological storage with top seal mudrocks.
Of course, the recent increase of federal tax credits for sequestration of carbon dioxide via direct air capture to <a href="https://theconversation.com/biden-signs-inflation-reduction-act-its-climate-promise-relies-heavily-on-carbon-capture-meaning-thousands-of-miles-of-pipeline-188591">$180/ton from its previous level of $50/ton</a> may privilege storage of carbon dioxide overuse in many projects, including those that might contemplate selling carbon dioxide for EOR purposes. However, since tax credits for the use of carbon dioxide were also recently ratcheted up from $30 to $130/ton, there may still be developers that deem this the more financially propitious course from a financial perspective. For example, revenue associated with EOR appears to be <a href="https://www.natlawreview.com/article/enhanced-oil-recovery-energy-transition">part of the business model</a> for the companies currently developing what is slated to be the world’s largest DAC facility, DAC-1 in Texas’s Permian basin. Thus, we should not be discouraging this path given both the potential climatic benefits of EOR, as well as the need to drive down direct air capture&#x27;s costs if it’s to play a substantial role in combating climate change.
However, at the same time, we should seek to ensure that EOR operations are conducted with integrity, and in a manner that maximizes the achievement of climate policy goals. Oil companies have sought to game the system and <a href="https://www.vox.com/energy-and-environment/2019/10/2/20838646/climate-change-carbon-capture-enhanced-oil-recovery-eor">avoid strict verification of the amount of carbon dioxide they claim to be storing through EOR operations</a>. In the context of federal support for direct air capture hubs, reporting requirements for any project that includes EOR should be extremely stringent. Moreover, government incentives and regulatory mechanisms should be designed to encourage those engaged in EOR operations to <a href="https://www.wri.org/insights/co2-direct-air-capture-plant-will-help-extract-oil-texas-could-actually-be-good-climate">utilize and bury as much CO2 as possible.</a> Finally, all EOR projects reach a point where operating costs are greater than waning revenue streams from fossil fuel sales. At that juncture, there is no economic motivation for operators to continue to pursue oil production. However, it would be salutary to provide incentives to maintain the viability of such sites as CO2-only storage facilities given lower unit costs compared to constructing CO2 storage facilities from scratch. Government incentives in the form of tax credits might help to drive down storage costs for the nascent carbon removal industry, accelerating its development.
EOR is assuredly a counterintuitive strategy for combating climate change. However, the optics of this approach should not keep society from considering the potentially salutary role that it can play, including in helping to scale up the carbon removal industry.
illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability &amp; Energy writers, their opinions do not necessarily represent those of illuminem.
<h6>Cover photo by <a href="https://unsplash.com/@zburival?utm_source=unsplash&amp;utm_medium=referral&amp;utm_content=creditCopyText">Zbynek Burival</a> on <a href="https://unsplash.com/photos/GrmwVnVSSdU?utm_source=unsplash&amp;utm_medium=referral&amp;utm_content=creditCopyText">Unsplash</a>​ </h6>

Don’t Rule out Enhanced Oil Recovery in Carbon Dioxide Removal Policymaking

It is becoming increasingly clear that achievement of the temperature objectives of the Paris Climate Agreement will require the global community to both engage in extremely rapid and aggressive decarbonization of the world economy and deployment of atmospheric carbon dioxide removal (CDR) approaches at a substantial scale. Of the integrated assessment model scenarios in the IPCC’s Fifth Assessment Report that achieve the Paris Agreement’s upper-level temperature targets, 87% contemplated the need for extensive deployment of CDR options in the second half of the century.

<h1>Introduction</h1>
It is becoming increasingly clear that achievement of the temperature objectives of the Paris Climate Agreement will require the global community to both engage in extremely rapid and aggressive decarbonization of the world economy and deployment of atmospheric carbon dioxide removal (CDR) approaches at a substantial scale. Of the integrated assessment model scenarios in the IPCC’s Fifth Assessment Report that achieve the Paris Agreement’s upper-level temperature targets, <a href="https://www.nature.com/articles/s41558-017-0045-1.pdf">87% contemplated the need for extensive deployment of CDR options in the second half of the century</a>.
The <a href="https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_SPM.pdf">IPCC’s Sixth Assessment Report</a>, released in 2021/2022, affirms this conclusion, stating that “deployment of carbon dioxide removal (CDR) to counterbalance hard-to-abate residual emissions is unavoidable if net zero CO2 or GHG emissions are to be achieved.” This may ultimately translate into the need to remove <a href="https://www.carbonbrief.org/analysis-what-the-new-ipcc-report-says-about-how-to-limit-warming-to-1-5c-or-2c/">hundreds of gigatons of carbon dioxide</a> from the atmosphere to meet the Paris Agreement’s temperature objectives.
The emphasis in recent IPCC reports has been on <a href="https://www.carbonbrief.org/in-depth-qa-the-ipccs-sixth-assessment-on-how-to-tackle-climate-change/">terrestrial carbon removal options</a>, including afforestation/reforestation, bioenergy with carbon capture and storage, and direct air capture. However, there is <a href="https://www.frontiersin.org/articles/10.3389/fclim.2021.664456/full">increasing recognition</a> that ocean-based approaches may also have to play a substantial role in building a viable portfolio of carbon dioxide removal options.
One of the most widely discussed of these ocean-based approaches is termed “ocean afforestation,” or “seaweed farming.” Wild seaweed incorporates dissolved inorganic carbon from the upper layer of the ocean into tissue through the photosynthetic process. The conversion of dissolved carbon dioxide into biomass, in turn, <a href="https://nap.nationalacademies.org/cart/download.cgi?record_id=26278&amp;file=127-146">results in drawdown of atmospheric carbon dioxide by air-sea fluxes into ocean surfaces. Some species, such as kelp, float near the surface because of gas-filled bladders in their leaves. When these bladders burst, kelp can sink to the deep oceans, or get locked away in sediments, potentially </a><a href="https://scholarship.law.columbia.edu/cgi/viewcontent.cgi?article=3743&amp;context=faculty_scholarship">resulting in the storage of carbon for hundreds to millions of years</a>. One study concluded that natural seaweed ecosystems <a href="https://www.nature.com/articles/ngeo2790">sequester approximately 173 million metric ton of carbon annually</a>.
Ocean afforestation entails large-scale cultivation of species such as kelp to try to supercharge carbon dioxide removal. It’s contemplated that long-term storage of carbon dioxide in kelp tissues can be effectuated <a href="https://www.nap.edu/catalog/26278/a-research-strategy-for-ocean-based-carbon-dioxide-removal-and-sequestration">by either the sinking of seaweed biomass or pumping it to depth</a>.
In recent years, a number of start-up companies have begun exploring the potential for large-scale seaweed farming for carbon removal purposes. For example, Maine-based <a href="https://www.runningtide.com/">Running Tide</a>, is growing kelp seeds in hatcheries, and then placing them on biodegradable buoys. The idea is that the kelp can capture carbon dioxide as the buoys float along on the surface of the ocean, with the buoys sinking deep into the ocean when the kelp reaches a certain weight, likely over a 6-8 month growth season. California-based <a href="https://pulltorefresh.earth/">Pull to Refresh</a> contemplates developing a fleet of semi-autonomous vessels that would tow vases in which giant bladder kelp can be grown, with the kelp eventually dying and sinking to the bottom of the ocean.
A number of recent articles in the popular press have, without much scientific analysis, touted this approach. This includes a recent Atlantic piece proclaiming that <a href="https://www.theatlantic.com/science/archive/2022/05/kelp-running-tide-carbon-removal/638421/">“[k]elp is weirdly great at sucking carbon out of the sky</a>,” and an <a href="https://www.npr.org/2021/03/01/970670565/run-the-oil-industry-in-reverse-fighting-climate-change-by-farming-kelp">NPR piece</a> echoing the claims of both Running Tide and Pull to Refresh that kelp farming could potentially store prodigious amounts of carbon dioxide. Indeed, Pull to Refresh contends that kelp cultivation could result in the storage of <a href="https://www.discovery.com/science/kelp">up to a trillion metric tons of carbon dioxide</a>.
I would like to take a more precautionary position in this article, both in terms of the actual carbon sequestration potential of ocean afforestation, as well as the specter of negative impacts of deploying this approach at large scales.
<h1>Sequestration Potential of Kelp-Farming</h1>
Kelp assuredly has remarkable carbon sequestration properties, <a href="https://hakaimagazine.com/features/kelp-gets-on-the-carbon-credit-bandwagon/#:~:text=Some%20players%20are%20anticipating%20seaweed,for%20restoring%20or%20farming%20kelp.">taking up roughly twenty times more carbon</a> than terrestrial plants of commensurate volumes. However, several recent studies have concluded that the contribution of kelp farming in a carbon removal portfolio would likely be very modest. For example, <a href="https://nap.nationalacademies.org/read/26278/chapter/1">a report</a> on ocean-based CDR approaches released late last year by the U.S. National Academies of Science, Engineering, and Medicine (NASEM), concluded that a “reasonably successful goal” for a kelp farming program would be to grow and sequester enough macrophyte biomass to sequester a tenth of a gigaton of carbon dioxide annually. This is <a href="https://us7.campaign-archive.com/?u=5ac0a2bfbf52dc67b0c7242c7&amp;id=85516d33f2">equivalent to 0.2% of annual global emissions</a>. To put this in perspective, very large-scale kelp farming might be able to sequester enough carbon to <a href="https://www.sierraclub.org/sierra/2021-2-summer/stress-test/can-farming-seaweed-put-brakes-climate-change">offset emissions associated with the aquaculture industry</a>, but this would pale into insignificance compared to the hundreds of billions of tons that we need from carbon dioxide removal approaches. It may thus be time to put aside the hyperbolic claims of some supporters, and view seaweed cultivation as a niche form of carbon removal.
Moreover, the study emphasized the titanic logistics of such an enterprise. Even sequestering 0.1 gigaton of carbon dioxide annually would require <a href="https://us7.campaign-archive.com/?u=5ac0a2bfbf52dc67b0c7242c7&amp;id=85516d33f2">an area equivalent to the land mass of Ireland</a>, or if sited in coastal regions, a 100-meter-wide continuous belt encompassing 63% of the global coastline. This seems wholly unrealistic, especially given <a href="https://www.elsevier.com/books/carbon-capture-and-storage/rackley/978-0-12-812041-5">the particularly imposing challenges</a> of constructing and operating farming systems in difficult offshore environments, where much of this activity would likely have to take place.
Recent research also calls into question even these modest estimates of potential carbon sequestration. A <a href="https://academic.oup.com/icesjms/article/79/3/585/6525671?login=false">new study by Gallagher et al.</a> concluded that seaweed farming could constitute a net source of carbon dioxide to the atmosphere. The reason is that as coastal waters flow through seaweed canopies they introduce large quantities of plankton and other organic material, which in turn can be fed upon by species that live among seaweed, such as sea squirts and bryozoan animals. These creatures breathe out large amounts of carbon dioxide as they consume these new sources of food supply. The authors conclude that rather than sequestering an estimated 50 tons of carbon dioxide per square kilometer, <a href="https://theconversation.com/kelp-wont-help-why-seaweed-may-not-be-a-silver-bullet-for-carbon-storage-after-all-178018">seaweed may emit as much as 150 tons per square kilometer annually to the atmosphere</a>.
A <a href="https://www.nature.com/articles/s41467-021-22837-2">recent study</a> by Bach, et al., which focused on carbon uptake by floating natural Sargassum seaweed in the North Atlantic, similarly concluded that ocean afforestation could constitute a net source of carbon dioxide, “<a href="https://www.nature.com/articles/s41467-021-22837-2">or, at best, contribute 0.0001–0.001% to the amount of annual CDR required in 2100 under a low emission scenario</a>.” This is due to a range of factors, including releases of carbon dioxide via calcification by species that habitate seaweed, and reduction of the growth of phytoplankton, which also take up carbon dioxide, due to reallocation of nutrient resources. Another <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GB007286">recent study</a>, employing new particle tracking models in the ocean, also concluded that the fraction of carbon that remains below the mixed layer for a century or more is far lower than previously estimated. This could further constrain the sequestration potential of kelp farming.
Finally, there are serious risks that a rush to monetize kelp farming could undermine confidence in ocean-based carbon dioxide removal strategies. Some analysts believe that kelp farming companies may start issuing “<a href="https://www.mainetechnology.org/mti-impact/success-stories/running-tide/">kelp carbon credits</a>” in voluntary markets as early as <a href="https://hakaimagazine.com/features/kelp-gets-on-the-carbon-credit-bandwagon/#:~:text=Some%20players%20are%20anticipating%20seaweed,for%20restoring%20or%20farming%20kelp.">this year</a>. Indeed, Pull to Refresh, is already encouraging companies to <a href="https://www.technologyreview.com/2021/09/19/1035889/kelp-carbon-removal-seaweed-sinking-climate-change/">“get in touch”</a> if they wish to purchase credits. However, this would be extremely injudicious at this point, and may continue to be so for the immediate future.
As the <a href="https://nap.nationalacademies.org/read/26278/chapter/1">NASEM ocean CDR report</a> of last year emphasized, existing biogeochemical monitoring systems may be inadequate to detect even a one-gigaton per year change in global inventories of carbon dioxide, and to distinguish it from natural fluxes. This may require development of sophisticated numerical modeling, and further development of Earth system models to take into account carbon cycles in higher ocean trophic levels. Moreover, while accounting for the dissolved organic carbon taken up by kelp, and distinguishing it background pools, will be <a href="https://www.nature.com/articles/s41467-021-22837-2.pdf">critical to carbon trading</a>, such monitoring is “<a href="https://www.nature.com/articles/s41467-021-22837-2.pdf">unfeasible</a>” currently. Finally, measurements of carbon stored in deep ocean regions or sediments currently rely on indirect calculations. The kind of empirical verification that should be required before carbon credits are issued will require development of new, and potentially expensive, methods, such as <a href="https://royalsocietypublishing.org/doi/epdf/10.1098/rsbl.2018.0236">environmental DNA</a>. This belies the rhetoric of companies, such as Running Tide, which tout the alleged “<a href="https://www.runningtide.com/carbonsinking">natural simplicity of this system</a>.”
<a href="https://verra.org/">Verra</a>, a non-profit organization that develops standards for mitigation approaches taken up in the voluntary carbon market, recently launched its <a href="https://verra.org/project/vcs-program/projects-and-jnr-programs/seascape-carbon-initiative/">Seascape Carbon Initiative</a>. The Initiative seeks to develop carbon crediting methodologies for “seascape carbon activities,” including seaweed/kelp farming. It will be extremely important that it fully engage with the complex science associated with this approach to ensure the integrity of this nascent field, <a href="https://reader.elsevier.com/reader/sd/pii/S0960982219308863?token=EE1387BCD803267473F416EB776C9D2FC4827DA4AFE851A7104D93C50B9005D885DF9AB7754F179AAA376E2F51F6B0A3&amp;originRegion=us-east-1&amp;originCreation=20220704222853">as well as to clearly outline requisite management strategies to minimize potential negative environmental impacts</a>.
<h1>Potential Risks Associated with Large-Scale Seaweed Farming</h1>
Large-scale seaweed propagation and sinking could impose risks in the upper layers of the ocean where seaweed would be grown, and at depth. In the near-surface ocean, it could reduce ambient nutrient levels and light availability. This could result in <a href="https://www.nature.com/articles/s41559-022-01722-1">reductions in phytoplankton production and trophic exchanges of energy</a> that could adversely impact fisheries and marine mammals. Widespread scale-up of seaweed farming also <a href="https://www.technologyreview.com/2019/04/23/136001/the-desperate-race-to-cool-the-ocean-before-its-too-late/">risks the introduction of invasive species</a>, carried by macroalgae into offshore ocean ecosystems. <a href="https://www.nature.com/articles/s41559-022-01722-1">One recent study</a>, for example, identified 1200 species hitching a ride on macroalgae as it drifted through the ocean. This raises the specter of the spread of disease or crowding out of other species. Seaweed cultivation at scale would also require a large buildout of infrastructure, including in deeper ocean waters than were most current seaweed farms have been sited. Even a modest goal of sequestering 0.1 gigatons of carbon annually might require <a href="https://nap.nationalacademies.org/read/26278/chapter/1">7.3 million hectares of ocean-based farm structures. This could result in entanglement of cetaceans and other vertebrates, hazards to navigation, and displacement of fisheries.</a>
In deeper portions of the ocean, “<a href="https://nap.nationalacademies.org/read/26278/chapter/1">likely . . . the least understood biome on Earth</a>,” sinking seaweed may reduce oxygen levels, and lead to acidification and eutrophication by increasing carbon dioxide and nutrient loads. Moreover, introduction of large amounts of particulate matter in the deep ocean could imperil visibility and contacts among mesopelagic species, “<a href="https://nap.nationalacademies.org/read/26278/chapter/1">similar to what might be expected from the improper disposal of tailings from deep-sea mining operations</a>.”
Of course, it also needs to be emphasized that seaweed farming can provide important co-benefits that should be taken into consideration in any policy process. This include <a href="https://oceanconservancy.org/blog/2019/04/26/what-is-a-kelp-forest/?ea.tracking.id=22HPXGJAXX&amp;gclid=Cj0KCQjwn4qWBhCvARIsAFNAMigGnX0Uy4LhPVhmgKC6AgkMl8P3BZ_POPayVu0xYhTr8VORp9SqexAaAtCrEALw_wcB">providing critical habitat for many ocean species</a>, <a href="https://www.fisheries.noaa.gov/national/aquaculture/seaweed-aquaculture">combatting ocean acidification</a> and lowering nutrient levels of nitrogen and phosphorus, which contribute to toxic algae blooms.
<h1>Is Seaweed Farming the Best Use of this Resource?</h1>
Some researchers question whether seaweed farming for the purposes of deep ocean carbon storage is the <a href="https://hakaimagazine.com/features/kelp-gets-on-the-carbon-credit-bandwagon/">optimal use of the resource from an environmental perspective</a>, or whether cultivation for other purposes might make more sense. Recent estimates are that <a href="https://reader.elsevier.com/reader/sd/pii/S0957582012001206?token=8B136C0860464234E7618F8F5488908B6A5B6062D5E0A26A43879631E6C953C79BD3FCF217D21C9CBA8D151DA6ECA18C&amp;originRegion=us-east-1&amp;originCreation=20220705030942">75% of farmed seaweed could be harvested annually</a> for various purposes that could help address climate change. For example, one study concluded that <a href="https://www.frontiersin.org/articles/10.3389/fmars.2017.00100/full">adding red seaweed to cattle feed can reduce methane emissions by as much as 99 per cent</a>. <a href="https://academic.oup.com/icesjms/article/70/5/1038/644026">Another study</a> contends that the optimal use of seaweed is as a replacement for fossil hydrocarbons in fuels, by converting seaweed biomass into a range of bioenergy products, including biogas or liquid or solid biofuels, or chemicals. Seaweed biofuels, for example, “<a href="https://scholarship.law.columbia.edu/cgi/viewcontent.cgi?article=3743&amp;context=faculty_scholarship">could mitigate about 1500 tons of carbon dioxide per square kilometer of seaweed cultivation</a>.” Seaweed could also help support other terrestrially-based carbon dioxide removal systems. For example, it could also be used as a <a href="https://link.springer.com/article/10.1007/s10811-016-1022-1">feedstock for bioenergy with carbon capture and storage systems</a>, <a href="https://link-springer-com.libproxy.berkeley.edu/content/pdf/10.1007/s10811-016-1022-1.pdf">helping to reduce potential competition for land with food crops</a>, or for <a href="https://link.springer.com/article/10.1007/s10811-016-1022-1">conversion into biochar for long-term deep-burial of carbon</a>. There’s also the potential to <a href="https://www.sciencedirect.com/science/article/pii/S1364032112007435?via%3Dihub">substantially reduce carbon dioxide emissions associated with fertilizer production</a>.
Policymakers, in conjunction with the scientific community, need to ascertain how to best use seaweed as an oceanic resource. This should not be primarily driven by the desire of companies wishing to cash in on carbon credits through any given method, but rather by approaches that maximize societal benefits. 
The journey continues.
Energy Voices is a democratic space presenting the thoughts and opinions of leading Energy &amp; Sustainability writers, their opinions do not necessarily represent those of illuminem.

Can Kelp Help? The Potential Role of “Ocean Afforestation”

The Carbon Dioxide Removal Leadership Act (CDRLA), new legislation recently introduced in the New York Legislature, may serve as a model for government carbon dioxide removal programs that seek to help facilitate large-scale deployment over the next few decades.  In this blog, Wil Burns and Toby Bryce will outline the bill’s key provisions.

Toby

There is growing scientific consensus that the global community, in addition to decarbonizing the world economy as aggressively as possible, will need to <a href="https://www.ipcc.ch/report/ar6/wg1/">remove gigatons of carbon dioxide annually from the atmosphere</a> to hold temperatures to between 1.5°–2.0°C above pre-industrial levels. Cumulatively, this translates into hundreds of billions of tons of carbon dioxide removal (CDR) over the course of the 21st century. While the bulk of these removals would occur in the second half of the century, as <a href="https://reader.elsevier.com/reader/sd/pii/S2590332220303596?token=B259987BC675887DDC493FE04F78F36A42DF47A8AB5CEB271CC02F949E5F56F1F863083330EF18459F47681F29DFC767&amp;originRegion=us-east-1&amp;originCreation=20220118220203">Morrow, et al. concluded</a>, “scaling up CDR capacity to the multi-gigaton scale, if feasible, would take several decades.” This emphasizes the need to mobilize quickly to deploy carbon removal now     
However, many CDR pathways, especially those that may deliver critical long-term sequestration of carbon, are currently in nascent stages of development, and as such are very expensive, at least in a world that does not accurately translate <a href="https://news.stanford.edu/news/2015/january/emissions-social-costs-011215.html">the true social cost of carbon</a> into policymaking. <a href="https://www.frontiersin.org/articles/10.3389/fclim.2021.636657/full">Recent studies</a> have indicated that government carbon procurement programs may be a critical component of efforts to ensure large-scale market adoption of CDR, <a href="https://openaircollective.cc/concrete-square-one-for-scaling-distributed-direct-air-capture/">helping to drive early stage niche discovery and penetration</a>, and facilitating scaling up and learning, driving down costs, and opening up new markets.
<a href="https://assembly.state.ny.us/leg/?default_fld=&amp;leg_video=&amp;bn=A08597&amp;term=&amp;Summary=Y&amp;Memo=Y&amp;Text=Y#jump_to_Text">The Carbon Dioxide Removal Leadership Act</a> (CDRLA), new legislation recently introduced in the New York Legislature, may serve as a model for government carbon dioxide removal programs that seek to help facilitate large-scale deployment over the next few decades.  In this blog, we will outline the bill’s key provisions.
The CDRLA authorizes the creation of a state-run procurement program to provide market support for durable CDR. The bill directs the state to purchase no less than 10,000 tons of CDR in 2024, and increases annual removal targets by 100 percent year-on-year over the course of its initial five-year authorization. The bill is standards-based – requiring clear additionality, a minimum of one-hundred-year durability, and third-party measurement, reporting, and verification (MRV) – and otherwise non-prescriptive in terms of what CDR pathways are eligible for purchase. These approaches may include terrestrial biomass-based carbon removal; enhanced rock weathering and other mineralization; ocean-based approaches; long-lived products such as concrete and other construction materials that sequester carbon dioxide; and direct air capture.
The CDRLA would facilitate state purchases through a reverse auction (sec. 76-0103), a bidding process whereby qualified suppliers of CDR would submit bids for removal in exchange for state payments. Reverse auctions have been recognized as an effective process in the context of scaling renewable energy deployment to <a href="http://blogs.edf.org/markets/2019/01/24/how-reverse-auctions-can-help-scale-energy-storage/">drive down prices and ensure reliable procurement</a>. The bill would authorize the state to pay a maximum average price per ton of $350 for qualified projects in 2024, with this sum decreasing by 5% annually, adjusted for inflation. The state’s CDR purchases under the bill would be financed by the repeal of a corporate tax subsidy on fossil fuel used for commercial aviation, one of the “hard-to-abate” sectors identified in the state’s landmark net-zero policy, the 2019 <a href="https://climate.ny.gov/">Climate Leadership and Community Protection Act</a>.
The bill also contains a number of provisions that seek to ensure the integrity of procured CDR in meaningfully addressing the threat of climate change, as well as to deliver the economic benefits of CDR -- <a href="https://carbon180.medium.com/carbontech-a-trillion-dollar-opportunity-154a9c62cf1c">estimated to be a multi-trillion-dollar market opportunity in the coming decades</a> -- to New York. Beyond additionality, durability, and verification, the bill requires a full lifecycle assessment (LCA) of all proposed CDR projects to ensure their carbon efficiency – i.e., that substantially more carbon dioxide is removed from the process than is emitted through its implementation and execution. Additionally, the bill explicitly prohibits procurement from any CDR project that incorporates <a href="https://www.energy.gov/fecm/science-innovation/oil-gas-research/enhanced-oil-recovery">enhanced oil recovery</a> (EOR) or otherwise facilitates the extraction or other production of fossil carbon (sec 76-0103(2)b). All CDR projects procured under the CDRLA must be located in New York state. This provision is designed to enhance the industrial development benefits of the policy.
The CDRLA could also effectively address environmental justice issues that have been raised in the context of carbon removal. For example, some justice groups have criticized offset mechanisms, which permit polluters to purchase credits generated by carbon removal approaches, as well as approaches that avoid or reduce emissions, from other entities. They contend this <a href="https://www.foodandwaterwatch.org/wp-content/uploads/2021/04/Oppose-GCSA-2021_Final-2.pdf">could prolong the lifetime of polluting sources, and thus the suffering of vulnerable communities in proximity to such facilities</a>. Others have <a href="https://www.sciencedirect.com/science/article/abs/pii/S2214629618309605">expressed concerns about the potential environmental impacts of siting carbon removal facilities in vulnerable communities</a>.
The CDRLA contains several provisions designed to further principles of justice. Before procurement begins under the program, the legislation directs the state to conduct a techno-economic survey of all CDR pathways in the state with a potential scale of 0.1Mt or greater (along the lines of California’s excellent 2019 “<a href="https://www-gs.llnl.gov/content/assets/docs/energy/Getting_to_Neutral.pdf">Getting To Neutral</a>” report). The bill further directs the state to perform a parallel survey assessing the community and social benefits and potential harms of each pathway (sec. 76-0102), with particular attention to New York’s “disadvantaged communities,” as defined in the CLCPA (which definition is currently <a href="https://grist.org/equity/new-york-environmental-justice-leaders-propose-new-definition-for-disadvantaged-communities/">under revision</a>). The legislation includes a clear “do no harm” standard, and every CDR project submitted for procurement must complete an “environmental justice and equity community engagement and assessment report,” which requires direct consultation with local communities (sec. 76-0105).
One of the benefits of climate policy that leverages public procurement – over, for example, a compliance mechanism – is the opportunity to incorporate non-price factors into the state’s purchasing decisions. The CDRLA explicitly directs the state to create a procurement “scorecard” (sec. 76-0107) that factors, in addition to price, “bid preferences” for equity considerations such as benefits to “disadvantaged communities,” job creation, the employment of union labor, and agricultural or ecosystem co-benefits. The scorecard also factors in techno-economic considerations such as energy and land-use efficiency, speed of delivery, durability in excess of one hundred years, and scale potential of the CDR pathway.
It bears repeating that climate policy at every level of government must strongly prioritize reducing emissions – as has been done in New York with the state’s landmark CLCPA. However, to reach our climate goals of limiting warming to 1.5°C or even 2.0°C, billions of tons of CDR will be required as well. This gigaton-scale CDR will not be possible without significant public sector support, and the CDRLA policy framework is an innovative initial step in this direction. Passing legislation is a significant, complicated challenge at any level of government. It will be interesting to watch in the coming years as the CDRLA advances in New York and perhaps other jurisdictions. States, as is often emphasized, are <a href="https://conversableeconomist.blogspot.com/2015/08/states-as-laboratories-of-democracy.html">laboratories for democracy</a> – and perhaps for effective climate policy as well.

Energy Voices is a democratic space presenting the thoughts and opinions of leading Energy &amp; Sustainability writers, their opinions do not necessarily represent those of illuminem.

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Wil Burns

Wil Burns

Don’t Rule out Enhanced Oil Recovery in Carbon Dioxide Removal Policymaking

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