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Energy from Water Vapour

Updated: Jun 29, 2020

The world of renewables is shortly to be joined by another source of clean energy, thanks to researchers in Israel who have managed to generate voltage from natural humidity.

Scientists think that water vapour in the atmosphere can potentially be a renewable source of energy. The concept of humidity as a source of energy is based on a recent study in the journal Nature that found that electricity can be generated between dissimilar metals when placed under specific humidity conditions.

In the study, researchers wanted to develop a small low-voltage battery that charges from the humidity in the air. Their basis of the concept was English physicist's Michael Faraday discovery that water droplets have the ability to charge metal surfaces in frictional contact and a recent study that showed certain metals can spontaneously build up an electrical charge when exposed to humidity.

Researchers conducted experiments so that they could determine the voltage developed between different metal pairs when exposed to high relative humidity. One of the authors of the study, Prof Colin Price from the Tel Aviv University, Israel explains that “once the relative humidity rose above 60%, a voltage began to develop between the two isolated metal surfaces. When we lowered the humidity level to below 60%, the voltage disappeared.”

In further tests, researchers were able to obtain different amounts of charge depending on the metal used whenever the relative humidity was above 60%. They even carried out the experiment in natural conditions and obtained the same results and the requirement of 60% relative humidity was fulfilled, something which “occurs nearly every day in the summer in Israel and every day in most tropical countries,” according to Prof Price.

This is going to be a game changer in the developed world as researchers think that humid air may be a source of electricity that can charge surfaces with a voltage of only one volt. One volt is roughly the same as the power stored in one small AA battery. However, Prof Price explains that it could prove to be a useful source of renewable energy in developing countries, “where many communities still do not have access to electricity, but the humidity is constantly about 60%."


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