Harnessing Carbon Removal Opportunities in Desalination

This report by RMI examines the potential for integrating electrochemical carbon removal (CDR) technologies into coastal desalination value chains. It identifies synergies between desalination processes—such as the use of brine as a feedstock and shared pumping infrastructure—and the potential for these integrations to mitigate the environmental impacts of brine discharge while contributing to global climate goals.

• Coastal desalination plants process over 150 million cubic meters of seawater daily, providing a significant opportunity for carbon removal. The sector is growing at 6%-12% annually, with most capacity currently in the Middle East and North Africa.
• Three primary electrochemical carbon removal approaches can be integrated into desalination: 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 to capture atmospheric CO2.
• Integrating carbon removal into desalination offers several synergies: using brine as a more energy-efficient feedstock than seawater, sharing pumping and pre-treatment infrastructure to potentially save up to 30% in energy, and using carbon removal as a pre-treatment step to soften water by removing calcium and magnesium ions, which can reduce the energy demand of the desalination process.
• eOAE projects can mitigate the environmental harm of desalination by using waste brine to produce alkalinity, which reduces the overall salinity of discharged effluents and helps reverse ocean acidification.
• The theoretical upper bound for carbon removal via desalination is 1 GtCO2/y, though RMI estimates a more realistic potential of 200 MtCO2/y under ideal conditions using current seawater processing volumes. Actual capacity will be limited by the availability of low-carbon energy and the ability to manage byproducts like hydrochloric acid or chlorine.
• Significant barriers to scale include high energy requirements (up to 2.8 MWh per ton of CO2 removed), the need for large-scale offtake or neutralization of acid byproducts (typically 1-5% v/v hydrochloric acid), and the requirement for rigorous environmental safety testing to ensure pH and salinity changes do not harm aquatic ecosystems.

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} }