MADesal - Passive Solar Water Desalination

Protyping progress in stages. Photo: MIT D-Lab/student team
Protyping progress in stages. Photo: MIT D-Lab/student team

Problem

This project aims to develop a working, passive solar-powered water desalinator for community members of Fort Dauphin, Madagascar.

Madagascar is currently in the midst of a climate-induced drought that has devastated the southern regions. Specifically, in Fort Dauphin, the capital of the southern Anosy region, much of the available water is non-potable due to high salt concentrations, and many residents must travel long distances to obtain clean drinking water. This task is often placed on community women, who may sacrifice productivity in order to obtain water for their families.

Working with the Tatirano Social Enterprise - a nonprofit that aims to empower women and lift people up by providing long-term access to clean water in Madagascar - we aim to explore desalination as a means of providing clean drinking water for families in southern Madagascar.

Image of the arid southern region of Madagascar
Image of the arid southern region of Madagascar. Photo: Harry Chaplin

Theory of change

We propose that if we prototype a working solar-powered water desalinator, then community members in Southern Madagascar will be able to make their own/access solar-powered desalinators. More people will then use the desalinators and decrease their salty water consumption which will allow them to have access to safe, un-salty drinking water and save time and money.

The inputs for our Theory of Change include ideally a working prototype of a solar-powered water desalinator, data from previously conducted surveys, and mentorship from Tatirano and D-Lab. Our major output would be that communities in Southern Madagascar will be able to make solar-powered desalinators to use. As an outcome, households will use the desalinators and salty water consumption will decrease. The impact will be that individuals will have cheaper and quicker access to sweet water. It would empower women as they wouldn’t have to spend as much time collecting water and could instead spend time on other initiatives.

Two potential solutions

Traditional desalination systems are often expensive, difficult to fabricate, require extensive maintenance, and are too large in scale. This project aims to explore smaller and more modular desalination systems that can utilize the locally available resources in Madagascar. Specifically, we aim to create a design that is passive and solar-powered, contributing to the ongoing work in desalination systems that have been piloted by Tatirano and past MIT teams.

Our project tackled two designs:

  • a multi-stage desalinator inspired by the thermally-localized multistage solar still (TMSS)
  • a single-stage desalinator based on a device created by the nonprofit Ecoswell
Conceptual diagram of a multi-staged solar device. Sunlight heats up a front plate to evaporate water that will then condense on a lower stage below. This condensed water will be without salt and will fall out of the desalinator for drinking. Successive stages recycle the heat from the previous stage to repeat this process. (Source: https://pubs.rsc.org/en/content/articlelanding/2020/ee/c9ee04122b)
Conceptual diagram of a multi-staged solar device. Sunlight heats up a front plate to evaporate water that will then condense on a lower stage below. This condensed water will be without salt and will fall out of the desalinator for drinking. Successive stages recycle the heat from the previous stage to repeat this process. (Source: https://pubs.rsc.org/en/content/articlelanding/2020/ee/c9ee04122b)

 

Left: mage of a 2-stage prototype built by our team at MIT. Wool provides insulation and the green cloth acts to wick water into the device. Photo: Susan Su  Right: Figure: Image of the inside of the MIT team two-stage desalinator after 6 hours of testing. Desalinated water was successfully collected on the condensing side of each layer. Photo: Susan Su
Left: mage of a 2-stage prototype built by our team at MIT. Wool provides insulation and the green cloth acts to wick water into the device. Photo: Susan Su  Right: Figure: Image of the inside of the MIT team two-stage desalinator after 6 hours of testing. Desalinated water was successfully collected on the condensing side of each layer. Photo: Susan Su

Next steps

The next steps of this project would entail further prototyping and designing to make the systems more efficient. The multi-stage desalinator prototype would benefit from a better water collection system and needs a system to replace the clamps we were using to hold it together. We would also like to investigate how the water collection capabilities of the two-stage device could improve with the addition of more stages. For our single-stage project, we would like to iterate on the design, perform more testing, and improve the water collection mechanisms. Currently the single-stage prototype can desalinate water and collect the water in its bottom corner.


MIT D-Lab Class

D-Lab: Development

Student team

MIT students unless otherwise noted.

  • Laura A. Schwendeman '23, Mechanical Engineering with a minor in Biomedical Engineering
  • Shruti Ravikumar '23, Computation and Cognition with a minor in Entrepreneurship & Innovation
  • Susan Su '23, Mechanical Engineering with a minor in Public Policy
  • Mahmoud Khalifa '23,  Mathematics with Computer Science

Community partners

Contact

Libby Hsu, MIT D-Lab Associate Director of Academics; Lecturer