
If You Harvested Body Heat from 44,000 People You Could Mine 1 Bitcoin per Month - mgliwka
https://motherboard.vice.com/en_us/article/vby7ny/bitcoin-body-heat-mining
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Bucephalus355
Worth noting that the Matrix was originally supposed to be about harvesting
CPU power from humans, not about using us as energy batteries. Concept was
changed by the studio to make it easier to understand as this was all before
cloud computing.

I think that was dumb, but must remember audiences were so different in 1999.
The Matrix was incredibly complicated for most people then, and they didn’t
have the benefit of all the summaries and even academic texts we have on it
today.

Also If you go back and read reactions to the marketing of the Blair Witch
Project at almost the same time, many people, while not believing it fully,
had a tough time understanding it was 100% a marketing campaign.

~~~
shagie
On the 'harvesting CPU power'... give the Hyperion Cantos by Dan Simmons a
read. I would put it up there as one of the greats of science fiction.

~~~
berbec
Agreed 100%. That series (4 books unless there's another sequel out) had such
a consistently excellent storyline, characters and innovative usage of
technology. It's not for the faint of heart, but well worth the 2k pages.

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gus_massa
> _An adult human body generates approximately 100 watts of power while at
> rest, and about 80 percent of this power is wasted as excess body heat.
> [...] on average the volunteers each contributed about 0.6 watts /hour of
> energy._ [1] [2]

> _What about mining Bitcoin in an ideal scenario, where the generators were
> perfectly efficient and able to harvest all 80 watts of excess heat produced
> by the body?_

For this calculations, it's not enough to use the energy/power numbers. You
must consider the entropy too.

To transform the heat into some useful energy form like electric energy, there
is a limit of how much you can transform by the Second Law of Thermodynamics
[https://en.wikipedia.org/wiki/Second_law_of_thermodynamics](https://en.wikipedia.org/wiki/Second_law_of_thermodynamics)

The maximal efficiency is 1 - T_cold / T_hot (in Kelvin). In this case, T_cold
is the temperature of the environment, that we can assume is some comfortable
value like 20° (293K, 68°F). And T_hot is the body temperature that is
approximately 37°C (310K, 96.8°F). So the maximal efficiency is 1 - 293K/310K
= 5.5%.

If the heat produced by the body is rest is 80W, the maximal amount of it that
can be collected and transformed to electricity (in a very optimistic
scenario) is 4.3W. They are collecting only 0.6W. It's imposible for
theoretical reasons to collect the 80W. [3]

[1] I'm not sure how the other 20W are dissipated. As heat?

[2] "0.6 watts/hour of energy" doesn't typecheck

[3] You can give the volunteers some drug to increase the temperature to 40°C
(313K, 104°F) while keeping them in a freezing environment 0°C (273K, 32°F)
This will increase the maximal theoretical efficiency to 12.7% (that is still
much less than 100%). Anyway, no sane ethical committee and/or insurance
company would approve the project.

~~~
keerthiko
> [1] I'm not sure how the other 20W are dissipated. As heat?

I would guess as chemical potential (stored in ATP, manufacturing and
converting proteins, endorphins, hormones and other bodily chemicals),
electrical signals (nervous system, muscle responses, brain activity) and
kinetic energy (blood flow, heartbeats, diaphragm, other internal organ
movements). Some of it is probably also internal temperature regulation for
different regions of the body, but maybe that's all in the 80W. eventually

> [2] "0.6 watts/hour of energy" doesn't typecheck

I ran their numbers, and I think they meant 0.6 kWh (which _is_ a unit of
energy, unlike watts/hour) -- 212 hours at 127.2W over all the volunteers, for
37 volunteers is around 0.7kWh per volunteer. Some of their numbers might be
more or less accurate than the others

> [3] You can give the volunteers some drug to increase the temperature to
> 40°C (313K, 104°F) while keeping them in a freezing environment 0°C (273K,
> 32°F) This will increase the maximal theoretical efficiency to 12.7% (that
> is still much less than 100%). Anyway, no sane ethical committee and/or
> insurance company would approve the project.

But the robots that will administer our future society while plugging us into
the matrix would ;)

~~~
gus_massa
About [1] All the energy in the ATP is eventually released. Unless you are
gaining weight or doing some mechanical work that is permanent (like lifting
boxes to the floor above you) almost all is released as heat. Perhaps some
energy is used to evaporate water, this may be important.

About [2]: Thanks for looking at their numbers. But they can't collect an
average of 127.2W because the maximal power that can be transformed to
electricity in this conditions is about 4W-5W. Also, the article claims that
they get less than the 1%, but I'm worry that in the press article they just
divided (0.6 watts/hour)/(80W) < 1% (ignoring the units).

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bdcravens
Worth noting that this article is from January 2018. Since then Bitcoin
difficulty has increased about 2.5x (was as high as around 3.5x at one point)
so you'll need more heat.

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yipeedipee
Time for the Matrix style pods so I can get all the coins ;)

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shinta42
Matrix

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airza
Life would indeed be easier if I could reverse the laws of thermodynamics

~~~
berbec
Just ask Maxwell's demon!

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cheeze
Don't give China any ideas...

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dang
Please don't post nationalistic flamebait, or any flamebait, to Hacker News.

[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

