FR EN ES Search
  1. Home
  2. Your solutions
  3. OSMOSUN solar desalination as a solution to alleviate water stress downstream of rivers

OSMOSUN: solar desalination as a solution to alleviate water stress downstream of rivers

All the solutions


  • Project initiator: Mascara, provider of the solution
  • Partners: local authorities (municipality of Hessequa, Western Cape Province via the drought emergency Fund) and French State (financial partners); Turnkey Water Solution (local partner for installation)
  • Duration of the project: 6 months in 2018-2019 (inauguration of the facility in February 2019)

Context of how the project emerged:

The Cape Province, and more broadly South West South Africa, is experiencing an unprecedented water crisis, with a structural decline in rainfall due to the El Niño climate phenomenon, exacerbated by the effects of climate change, and ever-increasing water consumption, particularly as a result of population growth. The threat of “Day Zero“, the day when water reserves will be depleted, is strong and leads the authorities to regularly impose water restrictions in the country’s main cities. The impacts would be terrible for both the economy and society, rekindling tensions between communities.

Solutions exist to avoid these urban water supply crises; they range from reducing consumption to increasing water storage and better management of existing resources. Another solution to combat water scarcity is the industrial production of fresh water by desalination of sea water (or brackish groundwater), which is under development in many countries. However, it often remains a very expensive and energy-intensive solution.

OSMOSUN® by MASCARA is a differentiating solution in this respect, being the world’s first industrial technology for photovoltaic solar desalination by reverse osmosis, without batteries, to provide access to drinking water, to everyone and everywhere, without any CO2 emissions. It has been deployed in the municipality of Hessequa, South Africa.


Strategy and  objectives

The installation of an OSMOSUN® solar seawater desalination unit has alleviated the problems of access to drinking water for the coastal community of Hessequa, since the freshwater dam on the Breede River, which had previously supplied the community, was no longer structurally capable of supplying the isolated villages located in the estuary. It was installed in a very short period of six months.

It can operate 8 to 10 hours a day and produces 100 m3 powered solely by the associated photovoltaic solar generator, and up to 300 m3 connected to the local grid for operation outside of sunny hours.  This hybrid mode of operation is used to cover the peak water consumption periods of the 3,000 inhabitants of the coastal village of Witsand.

The advantages of the solution:

  • modularity: OSMOSUN® reverse osmosis seawater desalination units can adapt to the water needs of the most remote water stress areas, to desalinate from 1 m3 to 10,000 m3 per day of seawater.
  • flexibility: to produce energy outside of sunny hours and up to triple, when necessary, the daily production (24 hours instead of 8 hours), it is possible to connect the desalination units to an alternative source of electricity, thus allowing a hybrid solar/grid operation.


The project’s innovative characteristics


Solar power eliminates CO2 emissions during production.

Furthermore, the OSMOSUN® process is designed to minimise the impact on the marine environment of seawater withdrawal and the diffusion of concentrates. This impact has been validated by a comprehensive independent environmental impact study.


The solution is competitive due to its low operating costs. The initial investment for the installation varies according to the site.

Technological innovation:

A patented technology to be marketed in 2017, OSMOSUN® allows the installation of small and medium capacity seawater treatment units that operate solely on solar energy and without storage batteries, a world first.

See the video

Results and perspectives

This project demonstrated the viability of the solution in an estuarine context and more broadly in a remote coastal community or one connected to an unstable power grid.

In the longer term, it will help to relieve the pressure of freshwater demand over the entire watershed by allowing coastal communities to become water self-sufficient.


MASCARA was the 2019 winner of the Solar Impulse Precious Water Award from the FAMAE Foundation for Environmental Innovation for its OSMOSUN® solution and winner of the Innovation Award from the ADEME Future Investment Program. It has also been labelled “Efficient Solution” by the Solar Impulse Foundation since May 2018.

How can this project be duplicated on other rivers?


If the estuary or delta suffers from saline intrusions, it is possible to treat this salt water to provide drinking water for the local population and agriculture.

#Water #Desalinisation #Solar #Delta

To know more

Photo credit: Mascara

Mettez à jour votre navigateur pour consulter ce site