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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub"></issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2025-447</article-id>
<title-group>
<article-title>Reviews and syntheses: Potential and limitations of oceanic carbon dioxide storage via reactor-based accelerated weathering of limestone</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Huysmans</surname>
<given-names>Tom</given-names>
<ext-link>https://orcid.org/0009-0001-0222-6383</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Meysman</surname>
<given-names>Filip J. R.</given-names>
<ext-link>https://orcid.org/0000-0001-5334-7655</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>van de Velde</surname>
<given-names>Sebastiaan J.</given-names>
<ext-link>https://orcid.org/0000-0001-9999-5586</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Biology, University of Antwerp, Wilrijk, 2610,  Belgium</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Marine Science, University of Otago, Dunedin, 9016, New-Zealand</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>National Institute of Water and Atmospheric Research, Wellington, 6022, New-Zealand</addr-line>
</aff>
<pub-date pub-type="epub">
<day>13</day>
<month>02</month>
<year>2025</year>
</pub-date>
<volume>2025</volume>
<fpage>1</fpage>
<lpage>23</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2025 Tom Huysmans et al.</copyright-statement>
<copyright-year>2025</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2025/egusphere-2025-447/">This article is available from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-447/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2025/egusphere-2025-447/egusphere-2025-447.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-447/egusphere-2025-447.pdf</self-uri>
<abstract>
<p>To achieve climate stabilization, substantial emission reductions are needed. Emissions from industrial point sources can be reduced by applying carbon capture and storage (CCS) methods, which capture carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) before it is released to the atmosphere. CCS applications typically target CO&lt;sub&gt;2&lt;/sub&gt; storage within geological reservoirs. Accelerated weathering of limestone (AWL) provides an alternative CCS approach, in which CO&lt;sub&gt;2&lt;/sub&gt; is stored as dissolved inorganic carbon in the ocean. At present, AWL technology remains at the pilot scale with no industrial implementation. Here, we review the proposed reactor designs for AWL, comparing them in terms of CO&lt;sub&gt;2&lt;/sub&gt; capture efficiency, CaCO&lt;sub&gt;3&lt;/sub&gt; dissolution efficiency, CO&lt;sub&gt;2&lt;/sub&gt; sequestration efficiency, and water usage. For this, we represent AWL as a four step process: (i) CO&lt;sub&gt;2&lt;/sub&gt; dissolution, (ii) CaCO&lt;sub&gt;3&lt;/sub&gt; dissolution, (iii) alkalinization (step only included in the case of buffered AWL), and lastly (iv) re-equilibration. AWL application is generally characterized by a large water usage and the need for large reactor sizes. Unbuffered AWL approaches show substantial degassing of CO&lt;sub&gt;2&lt;/sub&gt; back to the atmosphere after the process water is discharged. Buffered AWL compensates the unreacted CO&lt;sub&gt;2&lt;/sub&gt; by Ca(OH)&lt;sub&gt;2&lt;/sub&gt; addition, and hence prevents degassing, which substantially increases the CO&lt;sub&gt;2&lt;/sub&gt; sequestration efficiency. Yet, buffered AWL require a source of&amp;nbsp; CO&lt;sub&gt;2&lt;/sub&gt;-neutral Ca(OH)&lt;sub&gt;2&lt;/sub&gt;. The need for process water can be reduced by increasing the CO&lt;sub&gt;2&lt;/sub&gt; fraction of the gas stream or increasing its pressure. Further optimization of the pulverized carbonate particles could reduce the amount of Ca(OH)&lt;sub&gt;2&lt;/sub&gt; needed to buffer the unreacted CO&lt;sub&gt;2&lt;/sub&gt;. The anticipated CO&lt;sub&gt;2&lt;/sub&gt; sequestration efficiency of buffered AWL is comparable with that projected for large-scale CCS in geological reservoirs.</p>
</abstract>
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