

Scientists predict green energy revolution after new graphene discoveries - 3eto
http://www.independent.co.uk/news/science/scientists-predict-green-energy-revolution-after-incredible-new-graphene-discoveries-9885425.html

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trishume
This may well be a very important and interesting discovery but I cringed a
few times at the poor explanation of some of the science.

Example: "a million times thinner than human hair, yet more than 200 times
stronger than steel" the word "yet" suggests that it is very strong in an
absolute sense _despite_ being so thin. Yet in reality the comparison is to an
atom-thick sheet of steel, which is not very strong at all. This strength
doesn't easily scale, as evidenced by the fact that graphite (lots of graphene
layers) is not 200 times stronger that steel. (note that my explanation of the
science may not be perfect but it is better than this article)

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saosebastiao
> This strength doesn't easily scale, as evidenced by the fact that graphite
> (lots of graphene layers) is not 200 times stronger that steel.

This is an even worse explanation of the science. On the level of saying that
the strength of steel doesn't scale because I can bend pig iron with my hands.

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Animats
Materials-science articles about a modest advance in surface chemistry (which
is usually called "nanotechnology") are regularly being hyped into "big
commercial breakthrough real soon now" articles. Nature and MIT Technology
Review (which, despite the name, is a commercial company) are the big
offenders. Super-battery or fuel cell articles appear frequently, but never
seem to result in actual products.

Hydrogen isn't an "energy source", anyway. You have to crack it out of water
or pull it out of hydrocarbons. Those processes are uphill energetically. At
best, hydrogen is a storage medium.

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ChuckMcM
I agree with your assessment of the materials science articles but in this
case I think you missed the 'breakthrough' part.

Graphene allows positively charged hydrogen to pass through it. The thought
experiment is you create a vessel with an inner porous core, you wrap it in
graphene, and then you apply a vacuum. That device will pull any positively
charged hydrogen out of the atmosphere (which frankly isn't much except during
thunderstorms)

This behavior with graphene isn't unknown, the first example was noting that
graphene made for an exceptional water filter [1].

[1]
[http://www.manchester.ac.uk/discover/news/article/?id=11561](http://www.manchester.ac.uk/discover/news/article/?id=11561)

~~~
Animats
Even if that works, it may be subject to all the usual problems, such as
filter clog. This is a big problem with hydrogen fuel cells, which require
extremely pure hydrogen. It's a general problem with materials whose carefully
constructed surface structure has some unusual property. The surface structure
may be fragile.

A good example is NeverWet, the ultrahydrophobic coating. It repels water
because the surface is composed of tiny spikes, and water's surface tension
keeps the water supported on the surface of the spikes. This works so well
that mud will run off of shoes treated with it. The effect, though, doesn't
last long; even slight wear on the surface damages the micro-spikes. Reviews
of the product on Amazon agree: great at first, useless within hours to days
of use: ([http://www.amazon.com/Oleum-274232-Never-Multi-
Purpose/produ...](http://www.amazon.com/Oleum-274232-Never-Multi-
Purpose/product-reviews/B00DNQBFAW)).

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upofadown
The article goes on about the idea of collecting hydrogen from the atmosphere
using a graphene filter. There is no appreciable amount of hydrogen in the
atmosphere.

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Gravityloss
Using air humidity? Say we have 10 grams of water per cubic meter of air (so
about 1% of the total air mass), so about 1 gram of hydrogen.

At about 140 kJ/kg, and assuming a 10% reduction efficiency, and 100 watts per
square meter solar panel, it should be able to reduce 0,071 grams per second
or 260 grams per hour.

Assuming 10% of air moisture can be extracted, the wind passing through the
system to keep the water flow would need to be about 0,7 m/s. It's almost
always as windy as that.

The rough numbers are frighteningly good.

All we need is the system to be cheap.

~~~
danieltillett
... and some way to store and transport hydrogen. We can make hydrogen quite
cheaply right now (it is kindergarten technology), but once you try to store
and/or transport it then this is where things get really, really difficult
[1].

1\.
[http://en.wikipedia.org/wiki/Hydrogen_storage](http://en.wikipedia.org/wiki/Hydrogen_storage)

~~~
Gravityloss
No, I assumed (in hindsight could have mentioned it) that you could use the
hydrogen locally to generate electricity. The thing is connected to the the
electricity network.

But I realized that is roughly the momentary day power of the panel. The real
yearly average production is maybe 15% of that.

Forgot the panel efficiency with this
[http://en.wikipedia.org/wiki/Photovoltaic_system#mediaviewer...](http://en.wikipedia.org/wiki/Photovoltaic_system#mediaviewer/File:SolarGIS-
Solar-map-World-map-en.png)

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thret
A bit OT but this reminded me of Maxwell's demon:
[http://en.wikipedia.org/wiki/Maxwell's_demon](http://en.wikipedia.org/wiki/Maxwell's_demon)

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andretti1977
Oops the site says "you've been hacked by the sirian electronic army (sea)"

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SixSigma
No surprise there, they always hook it onto the cause de jour

