Drink your sun! Solar Energy for drinking water

Title of the research project

NANOSTEP - NANOfluid-based Solar absorption for Thermal Energy and water Purification

Scientific area 

Molecular dynamics simulations, Nanofluids, Solar Energy

Project coordinator

Pietro Asinari


Nearly one billion people worldwide lack access to safe drinking water, which represents a huge health, social and political problem. Our research investigates the use of solar energy to reduce this problem, also in far-away regions without access to the electricity grid.

Description of the research project 

Our approach is to use the energy from the sun, concentrated by suitable mirrors, to desalinate and purify water for making it drinkable. The key idea is to add to water, which flows through the focal point of the mirrors, some nanoparticles in order to absorb solar radiation directly. Particles can be microscopic and completely natural or nanoparticles designed with molecular simulation tools. In both cases, the objective is to get a better direct absorption of energy.

The direct absorption of energy from the sun allows high efficiency in evaporating water and inducing natural anti-bacterial processes, thus making water drinkable. All the considered particles can be easily extracted from the drinkable water obtained at the end of the process, so guaranteeing environmental sustainability of our approach.

In some regions of the world, also if sun is plentiful, local technology is not able to guarantee the maintenance of the traditional sun concentrating systems. In such cases, we can use heat surplus from energy generators installed in health emergency structures such as the ones of  “Medecins sans Frontières”. For this purpose we have developed a compact and purely mechanical desalination plant.

Impact on society 

Limited access to drinkable water is an extremely important health and social problem as it concerns one person out of nine. Moreover, water is often origin of international conflicts (for example between Pakistan and India) and the problem of water availability is also strictly connected to the one of energy supply, as desalination is a highly energy consuming process. Using simple and robust renewable technologies, offering also entrepreneurial opportunities to local populations, represent a big challenge in searching a solution able to mitigate the water problem.

Research results

 Nanostep project has developed and tested a solar, passive, low-cost desalinator with significative performance improvement due to efficient solar energy management. The project has experimentally demonstrated the possibility to distill almost 3 liters of pure water per square meter and per hour, from sea water, using less than 1Kw per square meter energy from solar radiation. This doubles the efficiency compared to any other device presented in the scientific literature.

In particular:

  • 1 publication on Nature Sustainability
  • 3 patents
  • New collaboration with universities, like MIT and EPFL
  • Participation to 1 new European project Horizon2020 (OYSTER) as partner
  • 2 new job positions at Politecnico di Torino 

Working group 

At Politecnico di Torino:multi-Scale ModeLing Laboratory - SMaLL

Eliodoro Chiavazzo, researcher

Matteo Fasano, Post-doc

Annalisa Cardellini, Matteo Morciano and Luigi Ventola, Ph.D students

International collaborations:

Massachusetts Institute of Technology (USA), Princeton University (USA) and Imperial College (UK).

National collaborations: Università di Brescia, Istituto Nazionale di Ottica (INO) and ENEA.

  • Budget: 150.000
  • Start date: 15/12/2015
  • End date: 14/12/2017