Nikola
Tesla, (1856- 1943) was a Croatia born (He was born to Serbian
parents in the village of Smiljan, Austrian Empire,modern-day Croatia
as per wikipedia) scientist and later became a naturalized American
citizen in 1891. He is remembered for his work in the fields of
high-voltage electricity and development of radio transmission, where
he made many discoveries and inventions of great value. The most well
known of his inventions is a coil that can generate high frequency
currents and a transformer, which boosted these alternating currents
to a high voltages. This coil is actually named after him and is
known as a Tesla coil. He also won fame for his victory over Thomas
Edison in the well-publicized "battle of currents," where
he proved that his alternating current was far more practical and
safe than Edison-brand direct current. Soon his technology dominated
the world's developing electrical infrastructure, and by 1900 he was
widely regarded as America's greatest electrical engineer.
One of
the pet projects of Nikola Tesla was the development of a system of
transmitting electric power without wires, though the project never
got completed because of lack of enough funds and obvious technical
flaws and glitches. In 1905, a team of construction workers in the
small village of Shoreham, New York, started work to erect a truly
extraordinary structure. Over a period of several years, they had
managed to assemble the framework and wiring for the 187-foot-tall
'Wardenclyffe Tower,' on top of which perched a fifty-five ton dome
of conductive metals, and beneath it stretched an iron root system
that penetrated more than 300 feet into the Earth's crust. Tesla
wanted to make this tower a part of a chain of "magnifying
transmitters" across the globe, saturating the planet with free
electricity and wireless communication as early as the 1920s.
According to his plans, towers like the one at Wardenclyffe, would
send columns of raw energy skyward into the electricity-friendly
ionosphere fifty miles up. To tap into this energy, all that the
customers would require would be a relatively small spherical antenna
on the roof of their homes along with a buried ground connection.
Between these two, enough electrical power would be available for
their domestic use. Tesla could never complete his tower and
eventually it was dismantled. However concept of wireless
transmission of electricity, has always remained as a topic of hot
interest amongst researchers in this field.
I
remember a visit that I had made many years ago, to a high power
radio transmitter of 'All India radio' used for transmitting medium
wave band radio signals. The engineer, who took us around, had given
us an interesting demonstration of the power that was being
transmitted. He had connected a normal 230 V household use,
incandescent bulb to a short loop of wire. When this wire loop- bulb
arrangement was taken near the transmission tower, the bulb had lit
up drawing electrical power from thin air, proving to us that high
frequency electrical power can be transmitted through thin air
without any cables.
Sun is
the largest source of energy for earth. To illustrate how much energy
the Sun sends to us, we can consider India's land mass. According to
an estimate, India's theoretical solar power reception, on only its
land area, is about 5000 Petawatt-hours per year. The daily average
solar energy incident over India varies from 4 to 7 Kilo watt hours
for every square meter of land with about 1500–2000 sunshine hours
per year. This is far more than current total energy consumption of
India. But the main problem in setting up a solar power station on
surface of earth is that it can generate power only during daylight
hours and that too when the sky is not cloudy.
To
overcome this problem, can we station our solar panels above in
space? This appears quite feasible with present status of space
technology. However we still would face two hurdles. Firstly how do
we send the electric power generated in space, down below on earth?
And secondly even if we have an arrangement to do that, how do we
keep the solar panels up in space in a stable position relative to
receiver's position on earth?
The
second problem is easier to solve. there is a specific region in
space, which consists of a single ring above the equator,
approximately 35,800 km high up into space and is known as a
Geostationary orbit and many more rings that are inclined to this
ring above equator. Any object placed at this height is pulled by
gravitational forces of earth and moon in such a way that they
exactly balance out each other, or in other words, a solar panel
placed here will move in an orbit with exactly same speed as that of
earth. This means that for an observer on earth, the satellite
appears stationary all the time.
Now
returning to the first problem, even if we have a solar panel
permanently placed in a geosynchronous orbit position above us, that
is generating electricity 24 X 7 in space, how do we get that power
back on earth. Perhaps Tesla's ideas might help!
In a
breakthrough, Japanese researchers have successfully transmitted
electric power wirelessly to a pinpoint target. But unlike Tesla's
'Wardenclyffe Tower,' they have done this by converting direct
current (D.C.) electric power generated by solar panels into
microwaves,( Microwaves are a form of electromagnetic radiation with
frequencies between 300 MHz (0.3 GHz) and 300 GHz. Compared to our
domestic electric power, which has a frequency of 50 or 60 Hz only.)
According
to Japan Aerospace Exploration Agency, or Jaxa, the researchers were
able to transform 1.8 kilowatts of electric power into microwaves and
transmit it with accuracy into a receiver located 55 metres away.
This breakthrough certainly brings space-based solar power closer to
reality. At the receiving point, the microwaves were successfully
converted into direct electrical current.
This
experiment done in Hyogo prefecture in western Japan last week,
really opens up great new possibilities for future. Yasuyuki
Fukumuro, a researcher at Jaxa, says that the concept can be put to
practical use around 2030. He adds; “a receiver set up on Earth
with an approximately 3-kilometre radius, could receive up to one
gigawatt of electricity, about the same as one nuclear reactor.”
Obviously,
the concept requires much more work, as establishing a principle is
quite different from producing a practical contraption or a system
that would generate power at high efficiency and low cost.
18th
March 2015
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