The search for renewable energy sources, which include wind, solar, hydroelectric, geothermal and biomass, is equally crucial for scientists and politicians, given their enormous potential in fighting climate change.
Un new study from Tel Aviv University published in Scientific Reports finds that water vapor in the atmosphere could serve as a potential source of renewable energy in the future. Power devices with water vapor batteries? We see.
The research
It was conducted by Prof. Colin Price in collaboration with colleagues from TAU's Porter School of the Environment and Earth Sciences. It is based on the discovery that electricity materializes in the interaction between water molecules and metal surfaces. “We tried to capitalize on a natural phenomenon: electricity from water”, explains prof. Price. “Electricity in thunderstorms is generated only by water in its different phases: water vapor, water droplets and ice. In just twenty minutes of development, clouds can make us go from droplets of water to enormous electrical discharges, lightning, hundreds of meters long."
Based on this research, the team began trying to produce a tiny low-voltage battery that works only on humidity in the air.
Tension in the air
Scientists conducted a laboratory experiment to determine the voltage between two different metals exposed to high relative humidity, while one is connected to earth. “We found that there was no tension between them when the air was dry”, explains prof. Price. “But once the relative humidity rose above 60%, a voltage began to develop between the two insulated metal surfaces. When we lowered the humidity level below 60%, the tension disappeared. When we conducted the experiment outside under natural conditions, we saw the same results.”
“Water is a very special molecule: during molecular collisions it can transfer an electric charge from one to another. Through friction, it can accumulate a kind of static electricity.", says the professor. Price. “We tried to reproduce electricity in the laboratory and found that different isolated metal surfaces accumulate different amounts of charge from water vapor in the atmosphere, but only if the relative humidity of the air is above 60%. This occurs almost every day in the summer in Israel and every day in most tropical countries.”
According to Prof. Price, this study challenges established ideas about moisture and its potential as an energy source.
Everyone knows that dry air causes static electricity and sometimes gives you a shock when you touch a metal door handle. Water is normally considered a good conductor of electricity, not something that can accumulate charge on a surface. However, it seems that things are different when the relative humidity exceeds a certain threshold.
The researchers, however, have shown that moist air can be a source of surface charges at voltages of around 1 Volt.
Towards a new and renewable energy?
In the future there may be a practical application: develop car's battery performance water vapor, which can be charged by water vapor in the air. The results can be particularly important.
Water vapor can become a new source of renewable energy in developing countries, where many communities do not yet have access to electricity, but humidity is consistently around 60%.
