Low-cost, Nature-based Solar Desal System

A team of scientists under the direction of researchers at King Abdullah University of Science and Technology (KAUST) have developed a low-cost, nature-based, sustainable solution to filter and purify seawater. Key ingredient: coal.

The new technology utilises pulverised coal fragments that are combined with cotton fibres and then moulded into a block to form carbonised compressed powder (CCP).  The block is placed above a container of seawater and heated with sunlight. As the water warms, it flows through the block. Upon reaching the surface, the water evaporates into steam, and is condensed into drinking water.

Marcella Bonifazi and Valerio Mazzone, from co-partner University of Zurich said: “To assist water flow into and through the CCP, the team incorporated cotton fibres through the material. The CCP’s raw materials are abundant in nature and low cost, as well as light-weight, [and] versatile,” adding, “The device produced fresh water at a record-breaking 12-15 litres/day/m², three times more than a traditional solar still and around one-third the cost of current state-of-the-art solar desalination technologies.”

The UN estimates that by 2025 1.2 billion people will be unable to access freshwater, and a further 1.6 billion people will live in countries which, “lack the necessary infrastructure to take water from rivers and aquifers.”

The key feature of this new desalination technology is that it is simple and low-cost. It has been demonstrated that a simple 16 m2 D system installed at a family farm can produce enough water to meet the drinking, cooking, and vegetable-watering needs of a typical rural family of four.

Not only has this system proved to be more efficient than other water desalination systems, it also harnesses a nature-based solution which discharges fewer pollutants into the oceans.

PERA Complexity, a Dutch company assisting in commercializing the technology, has commented: “D-SAL [the system] is more cost-effective and sustainable than existing technologies, as it offers a solution that is less capital intensive, simple to operate, doesn’t require electricity, or chemicals, and generates less brine discharge.”

Aluizio M Cruz, also from PERA Complexity added: “By using a 100% sustainable non-thermal fabrication process, we achieved a highly efficient and cost-effective relation between carbon atoms, surface area, solar energy, and water, all interacting in a complex coal structure.”

The team now plan to implement a pilot trail in rural parts of Northeast Brazil in the near future.