Enhancing hemispherical solar stills thermal performance by using nanotechnologies–recent advances and overview

Due to the increasing global population, climate change, and rising temperatures, the levels of freshwater are decreasing, which is worsening the problem of water shortage. The Earth's surface is predominantly covered by water, accounting for about 70 percent of the total area. However, just a mere 2.5 percent of this water is appropriate for drinking. The majority of freshwater sources consist of glacier zones and frozen rivers, leaving less than one percent of water usable for consumption and cultivation. Desalination is a suggested method to help address the issue of water scarcity. Desalination is widely recognised for its high energy consumption, which has a detrimental impact on the environment. Solar distillers have so evolved as an engineering solution for the process of desalination by utilising solar energy. Hemispherical solar stills are a form of stills often employed for desalination. They are recognised for their superior efficiency and productivity in comparison to alternative stills. The researchers have employed several methodologies to enhance the efficiency of hemispherical solar still and decrease the expenses associated with producing purified water. This review presents and analyzes the effects of utilising various nanotechnologies, either independently or in combination with other parameters, on the daily efficiency of hemispherical solar stills, the daily accumulation of water yield, and the cost of producing clean water. The review summarises the most noteworthy findings from past studies. Based on the examination of these results, suggestions are made for further studies on hemispherical solar stills.