**3. Solar desalination in Tunisia: perspectives**

Several coastal countries see water desalination as a solution to water scarcity [17]. In Algeria, a neighboring country of Tunisia, desalination is considered by water experts as the only solution present to avoid a future water shortage [18]. The very specific conditions of the Mediterranean Sea (freshwater at 19°C and a salinity of 38 g/L [19], while the waters of the golf course are at 30°C and a salinity of 40.5 g/L [20]) will result in lower cost per cubic meter of desalinated water Algeria started building large-scale desalination plants after the 2001 water crisis, with a total capacity of over 2 million m3 /d [21].

#### **Figure 2.**

*The statistical analysis of the direct normal irradiance (DNI) map for CSP-desalination in Tunisia (20 m above sea level) [35].*

#### *Desalination and Agriculture DOI: http://dx.doi.org/10.5772/intechopen.100197*

Also in Libya, which is Tunisia's second neighbor country, a serious effort has been made to develop additional water sources from desalination [22] and the country has about 10 desalination stations. The German Institute for Space Research carried out a study on the problem of water scarcity in the Arab region.

The main conclusion is that this shortage can be alleviated by resorting to water desalination by solar energy. Solar desalination can provide more than 85 billion m3 / year in some areas when the direct normal irradiance (DNI) exceeds 1800 kWh/ m2 /year (**Figure 2**). The x-axis represents the DNI, and the y-axis represents the quantity of desalinated water obtained (in billions of m3 /year).

This is the distribution of surfaces according to the radiation expressed in the production of desalinated water. Considering the increase in population in most countries of the South and particularly those which are arid like Tunisia, the desalination of seawater will be an important source of water in the water supply [36]. In addition, with the development of seawater desalination and the expected progress in terms of access to drinking water and sanitation (United Nations Sustainable Development Goal SDG 6), this sector could reduce its consumption. In energy by 15% by 2040 [37] everywhere, when political decision-makers wanted it, deserts were irrigated in several cities of the Middle East with desalinated seawater [38].
