Water vapor in the atmosphere may be prime renewable energy source


Date:
June 9, 2020
Source:
American Friends of Tel Aviv University
Summary:
A new study finds that water vapor in the atmosphere may serve as
a potential renewable energy source in the future.



FULL STORY ==========================================================================
The search for renewable energy sources, which include wind, solar, hydroelectric dams, geothermal, and biomass, has preoccupied scientists
and policymakers alike, due to their enormous potential in the fight
against climate change. A new Tel Aviv University study finds that water
vapor in the atmosphere may serve as a potential renewable energy source
in the future.


==========================================================================
The research, led by Prof. Colin Price in collaboration with Prof. Hadas Saaroni and doctoral student Judi Lax, all of 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 surfaces. It was published in Scientific Reports on May 6, 2020.

"We sought to capitalize on a naturally occurring 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.

Twenty minutes of cloud development is how we get from water droplets to
huge electric discharges -- lightning -- some half a mile in length."
The researchers set out to try to produce a tiny low-voltage battery
that utilizes only humidity in the air, building on the findings of
earlier discoveries. In the nineteenth century, for example, English
physicist Michael Faraday discovered that water droplets could charge
metal surfaces due to friction between the two. A much more recent study
showed that certain metals spontaneously build up an electrical charge
when exposed to humidity.

The scientists conducted a laboratory experiment to determine the voltage between two different metals exposed to high relative humidity, while
one is grounded. "We found that there was no voltage between them when
the air was dry," Prof. Price explains. "But 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. When we carried out the experiment outside in
natural conditions, we saw the same results.

"Water is a very special molecule. During molecular collisions,
it can transfer an electrical charge from one molecule to the
other. Through friction, it can build up a kind of static electricity,"
says Prof. Price. "We tried to reproduce electricity in the lab and
found that different isolated metal surfaces will build up different
amounts of charge from water vapor in the atmosphere, but only if the
air relative humidity is above 60%. This occurs nearly every day in the
summer in Israel and every day in most tropical countries." According to
Prof. Price, this study challenges established ideas about humidity and
its potential as an energy source. "People know that dry air results in
static electricity and you sometimes get 'shocks' you when you touch a
metal door handle. Water is normally thought of as a good conductor of electricity, not something that can build up charge on a surface. However,
it seems that things are different once the relative humidity exceeds
a certain threshold," he says.

The researchers, however, showed that humid air may be a source of
charging surfaces to voltages of around one volt. "If a AA battery is
1.5V, there may be a practical application in the future: to develop
batteries that can be charged from water vapor in the air," Prof. Price
adds.

"The results may be particularly important as a renewable source of
energy in developing countries, where many communities still do not
have access to electricity, but the humidity is constantly about 60%,"
Prof. Price concludes.


========================================================================== Story Source: Materials provided by
American_Friends_of_Tel_Aviv_University. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. J. Y. Lax, C. Price, H. Saaroni. On the Spontaneous Build-Up
of Voltage
between Dissimilar Metals Under High Relative Humidity Conditions.

Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-64409-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200609122912.htm

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