

How putting $10M into UBeam illustrates everything wrong with tech investing today - brock_r
http://lookatmeimdanny.tumblr.com/post/101432017159/how-putting-10m-into-ubeam-illustrates-everything

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Thorondor
This was already posted at
[https://news.ycombinator.com/item?id=8542091](https://news.ycombinator.com/item?id=8542091)

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suprasanna
I think it's important to note this was from last October (2014). And here is
somewhat of a response blog post from Suster (investor) around that time:

[http://www.bothsidesofthetable.com/2014/11/05/the-case-
for-o...](http://www.bothsidesofthetable.com/2014/11/05/the-case-for-optimism-
and-risk-at-startups/)

~~~
boomshucka
(this is not a swipe at poster).

This article by Suster is awful. The take down discussed physics, Suster
discusses "doubters". The take down did not suggest it wasn't possible to
transmit energy through sound waves, simply that it seemed very impractical to
be able to charge a phone without pretty drastic side effects.

~~~
mikeyouse
Another point though, the CTO of Ubeam had a MS in nuclear engineering from
MIT and was a deputy director of innovation at Raytheon -- I expect he knows a
bit of physics too. Their VP of Engineering has a PhD in acoustics and they
employ other specialist PhD electrical engineers..

I appreciate a good 'take-down' as much as the next person but I don't think
it's as clear cut as the napkin-math suggests.

~~~
boomshucka
You are likely right, it probably isn't clear cut. But if there is a response
to his discussion of physics, it should be around physics, not the fact that
he is a "doubter". The world would be in an awful place without any
"doubters".

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tzs
> So given a 100 dB SPL transmitter (goodness knows how much electricity that
> will need… anyone want to install a three phase outlet by the bed?)

I don't know either, but I do know that you can buy a 110 dB ultrasonic
transmitter [1] that is powered by 12 VDC @ 1A, so that sound level can be
achieved with 12 watts (the power spec is on the back of the unit, which is
visible in one of the photos). That's well below what will be sending anyone
to the electrician to get three phase power in their bedroom.

As far as efficiency goes, there has been published work on this. I'm
appending a comment I made in the discussion of this here 9 months ago that
cited and discussed an interested research paper in that area.

[1] [http://www.soundlazer.com/product/sl-01-open-source-
parametr...](http://www.soundlazer.com/product/sl-01-open-source-parametric-
speaker/)

[2]
[https://en.wikipedia.org/wiki/Sound_from_ultrasound](https://en.wikipedia.org/wiki/Sound_from_ultrasound)

\---------------------

Any IEEE members here who could take a look at the following paper, which may
shed some light on what is and is not possible here, and then summarize it for
us?

\----------

Roes, M.G.L.; Hendrix, M.A.M.; Duarte, J.L., "Contactless energy transfer
through air by means of ultrasound," IECON 2011 - 37th Annual Conference on
IEEE Industrial Electronics Society , vol., no., pp.1238,1243, 7-10 Nov. 2011

doi: 10.1109/IECON.2011.6119486

Abstract: An alternative approach to the wireless transfer of energy is
proposed, employing acoustic waves in air. Unlike conventional methods,
acoustic energy transfer is able to achieve energy transfer at high
efficiencies over distances that are large in comparison to the dimensions of
the transmitter and the receiver. This paper gives an overview of the
principle and explains the different loss mechanisms that come into play. A
theoretically limit on the achievable efficiency is calculated. It exceeds
that of a comparable inductively coupled system by an order of magnitude.
First preliminary measurements indicate that AET is feasible, although the
measured efficiency is lower than the predicted theoretical limit.

URL:
[http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=611948...](http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6119486&isnumber=6119266)

Update: I was able to get a 5 minute preview of the paper from DeepDyve.com
[1']. They got 53% efficiency at 1 meter, but that was at very low power
(something like 37 uW). They weren't using particularly high powered
transducers, though, so could have gotten more power if that had been what
they were aiming for, but probably still a long way from charging a phone.
They say that the challenge for acoustic energy transfer will be in developing
the high power transducers that will be needed.

[1'] For those who have not heard of DeepDyve, they provide access to a very
large number of journal articles for prices that are much lower than what the
journals charge for individual articles. Yes, I know that ideally all of this
stuff should be available to the public for free, but until that happens
DeepDyve is worth considering. They have a "Freelancer" plan that costs
nothing up front, and gives you 5 minute full previews of articles. You can
purchase "tokens" in packs of 5 for $20. You can rent an article for 30 days
for one token. They also have a $40/month subscription plan that lets you read
unlimited articles, and gives a discount if you want to buy a PDF. You can
cancel the monthly plan at any time, and your account converts to Freelancer,
and you can switch back to the subscription plan at any time.

