The search for renewable energy sources, which include wind, solar, hydroelectric dams, geothermal energy and biomass, has concerned scientists and policymakers, because of their enormous potential in tackling climate change. . A new study from Tel Aviv University reveals that water vapor in the atmosphere could serve as a potential renewable energy source in the future.
The research, led by Prof. Colin Price in collaboration with Prof. Hadas Saaroni and PhD student Judi Lax, all from TAU’s Porter School of the Environment and Earth Sciences, is based on the discovery that electricity materializes in the interaction between water molecules and metal. areas. It was published in Scientific reports May 6, 2020.
âWe sought to capitalize on a natural phenomenon: electricity from water,â explains Professor Price. “Electricity in thunderstorms is generated only by water in its various phases – water vapor, water droplets and ice. Twenty minutes of cloud development allows us to pass water droplets to enormous electric shocks – lightning – about 800 meters in length. “
Researchers attempted to produce a tiny, low-voltage battery that only uses moisture from the air, building on earlier findings. In the 19th century, for example, English physicist Michael Faraday discovered that water droplets could charge metal surfaces due to the friction between the two. A much more recent study has shown that some metals spontaneously build up an electrical charge when exposed to moisture.
Scientists conducted a laboratory experiment to determine the voltage between two different metals exposed to high relative humidity, while one is grounded. âWe found that there was no tension between them when the air was dry,â says Professor Price. âBut once the relative humidity rose above 60%, a voltage started to develop between the two insulated metal surfaces. When we lowered the humidity below 60%, the tension was gone. saw the same results.
âWater is a very special molecule. In molecular collisions, it can transfer an electrical charge from one molecule to another. By friction, it can create a kind of static electricity, âexplains Professor Price. âWe tried to replicate electricity in the laboratory and found that different insulated metal surfaces accumulate different amounts of charge from water vapor in the atmosphere, but only if the relative humidity of the air is higher. at 60%. This happens almost every day in the summer. in Israel and every day in most tropical countries. “
According to Professor Price, this study challenges popular beliefs about humidity and its potential as an energy source. âPeople know that dry air generates static electricity and that you sometimes feel ‘shocks’ when you touch a metal doorknob. Water is normally considered to be a good conductor of electricity, not something that can build up a charge on a surface. However, it looks like things are different once the relative humidity rises above a certain threshold, âhe says.
However, researchers have shown that humid air can be a source of surface charges at voltages of around one volt. “If an AA battery is 1.5V, there might be a practical application in the future: to develop batteries that can be charged from water vapor in the air,” adds Professor Price.
“The results can be particularly important as a source of renewable energy in developing countries, where many communities still do not have access to electricity, but the humidity is constantly around 60%,” concludes Professor Price.
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