
German student builds electromagnetic harvester to recharge a battery - hoag
http://phys.org/news/2013-02-german-student-electromagnetic-harvester-recharge.html
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bryanlarsen
You would think that phys.org would know their physics. He's adding an
inductive load to wherever the energy is coming from. In some cases that will
simply replace other loads, but in many cases it will add to the load,
increasing energy wastage.

~~~
wazoox
I fail to see how harvesting existing electromagnetic fields would increase
the load, unless we consider the potential loss of range?

~~~
whatshisface
Every bit of metal acts like an antenna. You could think of it as the receiver
creating it's own signal that counteracts the transmitter. (Powered, of
course, by the transmitter itself.)

~~~
cynwoody
Not unlike a hand-crank generator. Turning it without a load connected is
easier than with a load. Without a load, no current flows through the
generating coil. With a load, current flows and generates a counteracting
magnetic field that resists the turning force.

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tiziano88
Come on, this is silly, the article makes it seem like it's creating energy
from thin air, while of course it's adding a load to the EM field, which
results in an increased energy drain from the source. Obviously no one is
going to notice if you recharge an AA battery using this system, but it's not
any different than just plugging a charger straight into your (or your
neighbour's) power socket.

~~~
niggler
You clicked the page, ads were shown, mission accomplished!

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DasIch
What's interesting about this article is that after reading it you might get
the idea that the student created this device to recharge batteries and
produce electricity.

However when you read the announcement[1] of the university itself you learn
that he was awarded the price in _digital media_ because:

> "Dennis Siegel thematisiert die sich überall befindenden elektromagnetischen
> Felder[...]" > TRANS: Dennis Siegel thematizes the everywhere occuring
> electromagnetic fields)

and further

> "Die Jury hat an dieser Arbeit den feinen Humor der Arbeit, den gedanklichen
> Kurzschluss, die Fähigkeit zum konzeptuellen Brückenschlag, die sensible
> einfache Gestaltung sowie die Zukunftsorientierung des Projektes
> hervorgehoben und überzeugt"

> TRANS: The jury has emphasized and was convinced by the fine humor of the
> project, the mental short circuit [it's not clear what this refers to in the
> announcement], the ability to create conceptual bridges, the sensible simple
> design and future-orientation.)

After reading this announcement one might actually come to the conclusion that
this an art project and that the fact that a student created a device that
charges batteries using electromagnetic fields by itself is rather boring and
irrelevant. The fact that any high school student should have the necessary
theoretical knowledge to built such a device could also be a give away.

[1]: [http://www.hfk-
bremen.de/t/auszeichnungen/n/hochschule-f%C3%...](http://www.hfk-
bremen.de/t/auszeichnungen/n/hochschule-f%C3%BCr-k%C3%BCnste-bremen-verleiht-
hochschulpreise-2013)

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dhughes
Physorg? Ugh.

Didn't even bother click, came here to read comments instead.

Can HN please ban Physorg like everyone else?

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msandford
It's also quite illegal to take power from mains lines even inductively. If
this kind of thing catches on I imagine the manufacturer would have a lot of
lawsuits on their hands.

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DanBC
> _But that clearly isn't the point of his device. Instead, it highlights not
> only the fact that we live our lives in a constant state of bombardment of
> electromagnetism, but also that all of the energy from all of the collective
> devices in use in the world today, is currently going to waste._

I prefer the "fluorescent tubes under transmission tower lines"
demonstrations. Here's one link ([http://hacknmod.com/hack/field-of-
fluorescent-tubes-powered-...](http://hacknmod.com/hack/field-of-fluorescent-
tubes-powered-by-ambient-current/)) but there are others.

It's neat to be able to do. I'm pretty sure the energy harvested comes nowhere
near the energy used to create the parts, or assemble the device.

If you want to make a really simple demonstration that "there's power in the
air" you could try this experiment - light an LED from cell phone frequencies
(<http://www.creative-science.org.uk/mobile_LED.html>). (Good Luck getting an
OA91 diode, though.)

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jtchang
Didn't Tesla at one point envision giant coils that would basically give you
"wireless electricity" through the use of changing magnetic fields?

This is cool but I'd be worried if it caught on in any sort of scale.

~~~
yareally
Yes.

<http://en.wikipedia.org/wiki/Wardenclyffe_Tower>

I think the resulting resistivity and wasted electricity would make it
unfeasible for mass usage over distances even if it had been funded to
completion.

I wish portable device OEMs would adopt inductive charging more though. No
worrying about cables or broken ports.

~~~
csense
If you lost a $5 cable or broke your $1 charging port, the OEM is economically
motivated to get you to shell out a three-digit figure for a new phone.

Given this simple and obvious observation, the fact that phone manufacturers
have mostly dropped proprietary charging interfaces in favor of USB seems like
a minor miracle.

~~~
yareally
Yeah, very true. It's actually pretty easy to replace USB ports on many mobile
devices. I read about users doing it all the time on Android forums and rather
cheaply. Mostly depends on how easy the device is to open up and repair
though.

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jrockway
_The particulars of the electronics inside his device haven't been detailed
(likely to prevent copycats)_

More likely because this is hardly a new idea and people have been doing this
for decades. I remember reading in an _elementary school science book_ how
some farmers used to run fences under power lines going through their fields
to get some "free" energy out of the electrical grid. This did not go over
well with the electricity utility.

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tehwalrus
as others have said, you're either absorbing a wave (and blocking someone's
signal) or acting as an extra coil (and making the source do extra work).

It's perpetual motion nonsense to suggest mounting these on roofs to power
buildings.. Apparently phys.org is as bad as new scientist!

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glabifrons
This reminds me enormously of the simplest electronics project I ever put
together: A Crystal Radio back in the '70s. If you're not familiar with them,
they're not much more than a coil and a "cat's-whisker" (diode) and they are
powered by the radio-waves themselves.

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tantalor
Since this increases the load on the source, isn't this more like stealing
than harvesting?

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huhsamovar
This is AWESOME!

> He's won a 2nd place award in the HfK Bremen Hochschulpreis 2013 competition
> for Digitale Medien, for his efforts.

Who on Earth won _first_ place?

~~~
DasIch
The first price in this category went to someone who built a robot arm
controlled by the emotional reactions of a sensitive plant[1][2].

[1]: [http://www.hfk-
bremen.de/t/auszeichnungen/n/hochschule-f%C3%...](http://www.hfk-
bremen.de/t/auszeichnungen/n/hochschule-f%C3%BCr-k%C3%BCnste-bremen-verleiht-
hochschulpreise-2013)

[2]: <http://en.wikipedia.org/wiki/Mimosa_pudica>

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4bpp
I'm not convinced that the device actually does what it is advertised to do.
Considering that the student is associated with a "University of the Arts",
the non-disclosure of the layout becomes even more suspicious, as is the
implied claim of being able to harvest useful amounts of energy from Bluetooth
transmitters.

It would be quite in line with German culture for somebody to have no qualms
about lying for the purpose of calling public attention to some perceived
environmental threat or health risk (think the Green party scaremongering
against genetically modified crops using flourescent dyes) and then saying it
was all art for a good cause if called out on it.

~~~
killerpopiller
WTF? I read your second paragraph twice, wouldn't believe my eyes.

You claim that publicly lying is part of the German mentality?

