Can solar stills produce drinkable water in freezing temperatures?

Operating in Freezing Temperatures

Solar stills, also known as solar stills or solar desalination units, can be effective in freezing temperatures, but their performance is limited. In ideal conditions, a solar still can produce up to 1 liter of clean water per hour. However, in temperatures below 0°C (32°F), evaporation rates decrease by approximately 50% for every 10°C (18°F) drop in temperature.

Design Considerations

To optimize performance in freezing temperatures, consider the following design modifications: increasing the still’s surface area, using dark-colored or black surfaces to absorb more solar radiation, and employing a transparent lid or window to minimize heat loss. Additionally, using a solar still with a built-in heat exchanger or insulation can help maintain a stable water temperature and improve efficiency. For example, a well-insulated still can maintain a water temperature of around 10°C (50°F) even in temperatures as low as -20°C (-4°F).

Real-World Applications

In extreme environments, solar stills have been used successfully to produce clean drinking water in temperatures as low as -40°C (-40°F). For instance, a team of researchers in Antarctica used a solar still to produce water for drinking and hygiene purposes during a 6-month expedition. By employing a customized still design and using solar radiation as the primary energy source, they were able to produce enough water to meet their needs despite the extremely cold temperatures.