Harnessing Carbon Removal Opportunities in Desalination

The report examines how coastal desalination plants can integrate carbon removal technologies, such as Direct Ocean Capture (DOC), Electrochemical Ocean Alkalinity Enhancement (eOAE), and Direct Air Capture (DAC), by leveraging existing seawater pumping infrastructure and brine outflows. It identifies significant synergies, including reduced energy costs when using concentrated brines and potential energy savings of up to 30% through shared infrastructure. While theoretical carbon removal capacities are high—with eOAE potentially reaching 200 MtCO2/y under ideal conditions—the report highlights critical constraints such as high low-carbon energy requirements (up to 2.8 MWh/tCO2), the need for large-scale acid or chlorine byproduct offtake, and the necessity for rigorous environmental safety testing regarding pH and salinity changes in marine ecosystems.

• Integrating carbon removal into desalination offers several operational synergies: using concentrated brines as feedstocks reduces energy intensity per ton of CO2 removed, and sharing pumping and pre-treatment infrastructure can yield energy savings of up to 30% compared to standalone projects.
• Three primary electrochemical carbon removal approaches are identified for integration: Direct Ocean Capture (DOC) which extracts dissolved inorganic carbon from seawater; Electrochemical Ocean Alkalinity Enhancement (eOAE) which increases the ocean's CO2 absorption capacity by returning a base stream to the water; and Direct Air Capture (DAC) which uses brine-derived base streams as solvents for atmospheric CO2.
• The potential scale for carbon removal is significant but varies by method: DOC could capture approximately half of the ~4 Mt of CO2 currently present as dissolved inorganic carbon in treated seawater, while eOAE has a theoretical upper bound of 1 GtCO2/y, with RMI estimating a more realistic 200 MtCO2/y under ideal conditions.
• High energy demand is a primary barrier to scaling; electrochemical processes can require between 1.9 and 2.8 MWh (7 to 10 GJ) of electrical energy per ton of CO2 removed, making the availability of low-carbon energy critical for achieving net-negative emissions.
• The large-scale deployment of eOAE and DAC is constrained by the need to manage acid or chlorine byproducts; specifically, the market for hydrochloric acid (HCl) is too small to absorb the volumes produced at scale, necessitating partnerships with alkaline mineral providers for neutralization.
• Environmental safety and regulatory clarity are essential for deployment, as interventions that cause significant local changes in pH or salinity can harm aquatic ecosystems, and some jurisdictions may classify the release of processed materials as waste disposal.

APA

RMI (2025). Harnessing Carbon Removal Opportunities in Desalination. https://rmi.org/resources/harnessing-carbon-removal-opportunities-in-desalination/

Chicago

RMI. Harnessing Carbon Removal Opportunities in Desalination. 2025. https://rmi.org/resources/harnessing-carbon-removal-opportunities-in-desalination/.

Wikipedia

{{cite report |author=RMI |title=Harnessing Carbon Removal Opportunities in Desalination |date=25 June 2025 |url=https://rmi.org/resources/harnessing-carbon-removal-opportunities-in-desalination/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2025harnessing, author = {{RMI}}, title = {{Harnessing Carbon Removal Opportunities in Desalination}}, institution = {RMI}, year = {2025}, month = jun, url = {https://rmi.org/resources/harnessing-carbon-removal-opportunities-in-desalination/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }