The first battery-free solar-powered desalination unit on the African continent      

On the 28th of May 2018, the construction of the first desalination system built by Enabel was completed. Enabel, in cooperation with the Brussels’ Region Environment Fund (IBGE-BIM), started earlier this year with the installation of desalination systems in 6 different communities in Mozambique’s Gaza province, where the water sources are too saline for drinking. Through an innovative process groundwater is filtered using solar power without having to use a battery to store the energy, making this the first battery-free solar-powered brackish groundwater desalination unit in Africa (see below article for technical information on the process).

Two international companies with Mozambican branches were chosen to install the water supply network and taps, as well as to carry out further operation, maintenance and management. Every district has one operator (six in total) and there is one general manager in Chokwe to respond to problems or questions. On the 28th of May the community of Manhiça tested the quality of the water and the public taps for the first time. With some reluctance the community opened the taps and tasted the water, which was followed by a positive reaction by the village chief and all the people present.

In that same last week of May, during the annual meeting of the water and sanitation sector, the government of Mozambique reiterated its commitment to provide drinking water to the entire Mozambican population by 2030, as part of the Sustainable Development Goals (SDGs). SDG 6 targets to achieve universal and equitable access to safe and affordable drinking water, as well as adequate and equitable sanitation and hygiene for all by 2030. It is estimated that in Mozambique 55% of the population currently have access to water: 43% in rural areas and 77% in urban areas. Last year, 80 water supply systems and 3,000 manual pumps were built in the entire country. The Minister of Public Works, Housing and Water Resources stated that in 2018 the construction of more than 140 water supply systems is planned. Special attention will be given to desalination systems given the presence of mostly unclean and brackish water in Mozambique. With a long and strenuous road ahead to achieve SDG 6, Mozambique can count on strong cooperation partners such as Enabel for support, expertise, and innovative solutions. 

The Water Gaza project of Enabel entered its last phase and will complete all activities at the latest beginning of 2019. Thanks to the project 23 water supply systems have been built in the Gaza Province, benefitting 51,000 people, which is around 23% of the rural population in the districts of Northern Gaza. Furthermore, Enabel has put a strong focus on digitisation, leading to the recognition of Gaza as the first province in the whole of Mozambique with a complete and reliable database on water infrastructures (Akvo Flow Database). Lastly, innovative solar-powered desalination units are being built in five other towns similar to Manhiça in order to provide the population with drinking water close to home.

Desalination has shown to be a viable solution for rural areas in Mozambique, where sometimes up to 70% of the water sources are too salty to safely drink. Enabel has played an important role in advocating these innovative technologies and has provided the Mozambican government with a successful pilot case with its Water Gaza project. Furthermore, Enabel worked strongly on guaranteeing the sustainability of the project by training local staff, as well as contracting Mozambican private companies for the management of the water supply systems and the distribution. Enabel involved the Mozambican government from the start by encouraging new innovative solutions for the water supply issue in Mozambique. Through the use of solar panels the project has even made an innovative link with SDG 7, promoting affordable and clean sustainable energy for all. The new projects of Enabel in Mozambique specifically focus on SDG 7, as they aim to increase access to renewable electricity in rural areas through capacity building of the Ministry of Energy (CB MIREME project) and investments in renewable energy systems (RERD II project). In conclusion, the Water Gaza project is a small, but important step in Mozambique’s road to achieving SDG 6 and will benefit the general livelihood of the target communities in Northern Gaza.                  



Technical info on desalination with solar energy without use of a battery      
The groundwater is pumped through two different kind of filters: the first one filters out the suspended solids (e.g. sand particles), while the second one further pre-treats the brackish water. In a third phase this pre-treated water will be transferred through a pump under pressure which stows the water through membranes of reverse osmosis. Such membranes reject most of the dissolved salts and produce drinking water with a salt concentration of less than 400 uS/cm. The drinking water is stored in elevated water tanks, while around 25% of the water is rejected in a separate basin. This entire process is powered by solar panels without the use of a battery. This is made possible by a simple and patented device that stores pressurized water, allowing pressure variations up to 90% power swings during production. In addition, rotary positive displacement pumps (more than 92% output of water) are used instead of centrifugal pumps (with output limited to 50 to 60%). Moreover, energy is recuperated from the concentrates by recirculating it through a recuperator through the membranes. Both innovative adjustments reduce energy consumption with almost 60% and optimise the lifespan of the membrane (5 to 7 years).


This article was written by Anke Van de Velde with the valuable input of Hélder Cumbi and revised by Evert Waeterloos.