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Workshop Report: Low Carbon Desalination: Status and Research, Development, and Demonstration Needs 

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The combination of low-carbon energy source and desalination systems raises several questions in relation to intermittent operation, dispatchability, grid integration, and both energy and water storage as elements of an overall energy water system.

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During 17-18 October 2016, the Massachusetts Institute of Technology (MIT) brought together an international panel of experts from academia, industry, and government for a workshop on driving down the carbon footprint of desalination systems. Organized at the request of the Global Clean Water Desalination Alliance and sponsored by the MIT Abdul Latif Jameel World Water and Food Security Laboratory, the workshop produced a preliminary report that highlighted the following points:

• Significant opportunity exists to couple existing large-scale renewable power systems, such as wind and photovoltaic systems, to existing large-scale reverse osmosis systems to provide low carbon desalination at low energy prices. Better understanding is needed around system integration and cost optimization relative to intermittent operation and/or energy and water storage options.

• Integrating desalination with low-carbon grids at large-scale can provide grid services, such as significant flexible load or demand response, possibly helping to flatten demand and act as a counterpoint to intermittent supply.

• Integration desalination at small-scale can provide clean water in areas of transient or sustained water scarcity with limited or non-existent grids. These desalination systems can also provide the dump load or demand response needed to maintain the stability of the associated microgrid.

• For desalination systems specifically, process improvements for energy efficiency, hybrid desalination technologies, advanced pretreatment, and fouling control methods as areas of highest current Technology Readiness Level (TRL) and potential impact. These combinations are candidates for development and demonstration. Next generation membranes are considered to have high potential impact, but lower TRL, suggesting value for additional research and development. Salinity gradient energy recovery, forward osmosis, and membrane distillation can be considered as relatively lower TRL and impact.

• For integration with low-carbon power sources, PV-RO and wind-RO are considered having highest potential impact and technology readiness, suggesting that demonstration at scale may be timely. CSP-thermal desalination hybrids, optimized power-water cogeneration, system optimization with intermittency, and autonomous grids and small scale integration are considered to have lower technology readiness but significant potential impact; these technologies may be considered for further research and demonstration. Salinity gradient power are considered as a low priority.

• Further research should be done to develop the TRL and impact scores systematically.
   

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