Compressed Blocks of Coal Could Enable Solar-Powered Off-Grid Water Purification

A new study shows that compressed blocks of pulverized coal can be used as the foundation for solar-powered off-grid water purification. The technology is already being advanced by commercial partners to achieve pilot-scale production of drinking water.

Compressed Blocks of Coal Could Enable Solar-Powered Off-Grid Water Purification.
KAUST scientists are developing a new technology that can produce freshwater for a fraction of the cost of current state-of-the-art solar desalination technologies. Image Credit: © 2021 KAUST.

For a long time, Andrea Fratalocchi from KAUST has been studying dark-colored materials that strongly soak up sunlight to power seawater desalination.

The idea of innovative use for coal struck Fratalocchi when he read about the economic difficulties of ending its use to generate power. “The two ideas clicked together: why don’t we use coal for a new economy in water desalination?” recalls Fratalocchi.

Fratalocchi and his colleagues started exploring blocks of carbonized compressed powder (CCP), a microporous material created by forcing powdered coal together under pressure. The researchers enabled water flow into and through the CCP by adding cotton fibers through the material.

A block of this material was placed over a saltwater-filled container such that the cotton fibers touched the water. Upon warming the CCP by sunlight, water was drawn up through the device and evaporated from its hot surface. A condenser placed on the device captured the freshwater. Seawater can be used to wash off the salt left behind in the CCP.

CCP is abundant in nature and low cost, as well as lightweight, versatile and highly scalable from a fabrication point of view. The device produced fresh water for around one-third the cost of current state-of-the-art solar desalination technologies.

Marcella Bonifazi, Postdoc, KAUST

Bonifazi worked on it as a postdoc in Fratalocchi’s lab.

The device could provide fresh water to the 1.6 billion people around the globe facing economic water shortages. According to the UN, access to water for agricultural production, even if only for supplemental watering of a vegetable garden or small crops, can make the difference between farming as a mere means of survival and a reliable source of livelihoods.

Valerio Mazzone, Postdoc, KAUST

Mazzone also developed the device while working as a postdoc. A 16 m2 CCP desalination system can synthesize adequate water to fulfill the drinking, cooking and vegetable-watering needs of a standard family of four, the researchers calculated.

The team has collaborated working with a commercial partner, Netherlands-based PERA, to develop the device such that it can be commercialized.

PERA is developing a pilot in Brazil for brackish water desalination as a permanent solution not only for drinking and cooking needs but also for basic food production, benefiting millions of people in Brazil’s semiarid northeast region.

Marcella Bonifazi, Postdoc, KAUST

Journal Reference:

Mazzone, V., et al. (2021) Clean Carbon Cycle via High-Performing and Low-Cost Solar-Driven Production of Freshwater. Advanced Sustainable Systems.


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