# The Synergy of Renewable Energy and Desalination:
## 1 Introduction  
The amount of freshwater available has drastically decreased due to rapid population growth, industrialization, and recurring dry extremes. Merely 3% of freshwater comprises all of Earth's water resources, with saline water making up the other 97% [1]. One-fifth of the world's population, according to the World Health Organization (WHO), resides in nations where freshwater is scarce [2]. Therefore, more attention is paid to alternatives to natural freshwater sources [3]. One of the primary methods for potable water production is water desalination, which is the process of extracting salts and minerals from brackish or salaty water to create pure potable water. For this reason, desalination of seawater (SW) or brackish water (BW) is one of the essential solutions to the worldwide problem of water scarcity [4]. The process of desalination is quite an effective approach for potable water production [5, 6]. According to [7], about 1% of the world's drinking water comes from desalination, and this amount is rising annually. A new production capacity of 5.7 \(\times\) 10\({}^{6}\) cubic meters per day would be added with an anticipated USD 10 billion investment over the following five years. By 2030, this capacity is anticipated to double. Around 18,000 desalination facilities with a combined gross output of 86.55 million m\({}^{3}\)/day, or 22,870 million gallons per day (MGD), were in operation as of the end of 2015. Since then, the total number of desalinationunits has reached almost 21,000 in 2022 [8]. The total amount of freshwater production from desalination plants worldwide is approximately 35 \(\times\) 10\({}^{9}\) cubic meters per year [9]. Approximately 44% of this capacity, or 37.32 million m\({}^{3}\)/day or 9860 MGD, is found in North Africa and the Middle East. The \"hot spots\" for faster desalination growth over the next ten years are anticipated to be Asia, the US, and Latin America, even if desalination within those regions is predicted to increase steadily at a pace of 7 to 9 percent annually. The majority of EU desalination plants are found in the Mediterranean region, where demand for them is expected to be highest in the future. However, the main barriers to the general adoption of desalination systems are the substantial upfront technology costs and the large amount of energy that is needed for the technological processes. The production of brine, a hyper-saline byproduct, and the desalination process's relatively high energy consumption are its principal downsides. Furthermore, the emissions of greenhouse gases (GHGs) from fossil fuel-powered desalination plants have a detrimental effect on the environment and contribute to global warming by emission of CO\({}_{2}\). As mentioned, among the main drawbacks of desalination is that it uses a lot of energy, which contributes to global warming [10]. Renewable energy is a viable substitute for fossil fuels because it is clean and abundant, making it a good option for running desalination plants. For this reason, addressing the water-energy linkage is essential to moving towards a sustainable future. Consequently, it is crucial to incorporate renewable energy sources (RES) into the desalination process. Integrating RES into desalination systems can significantly improve sustainability. Renewable energy sources, such as solar, wind, and geothermal, offer promising solutions to mitigate these challenges related to GHG emissions and can potentially provide sustainable alternatives for desalination [11]. The transition to desalination techniques that are both affordable and ecologically benign is being made easier by technological advancements. The increasing demand for clean water around the world requires the use of renewable energy. Over the past decade, renewable energy sources-based desalination has primarily been carried out in areas like the Middle East that are known for having significant wind power and an abundance of sun radiation. In 2017, there were around 131 renewable-powered desalination facilities.