
Embodied energy of digital technology - femto
https://www.lowtechmagazine.com/2009/06/embodied-energy-of-digital-technology.html
======
l0b0
The "source" is just a list of almost 200 publications, with no indication of
which numbers come from where. So it's effectively unsourced. That means it's
either bullshit, terrible reporting, or both, and there's no reason to believe
this over i-have-an-agenda.org.

I've got karma to burn, so bring it. But it really is time that reporters get
their bloody act together. Without the research this is as worthless as an
opinion piece, and it's not going to convince anybody who needs convincing.

~~~
amirhirsch
The fun part is seeing those ranges for silicon after having spent the last
several weeks researching ways to decrease the energy costs of producing
“solar grade” (one nine less than monocrystalline wafer) silicon from silica.
There’s a paper showing 1.6kg of 6-nines silicon from rice hull ash in 6hours
in a 50kw arc reactor (300kwh)
([https://pubs.rsc.org/en/content/articlelanding/2015/gc/c5gc0...](https://pubs.rsc.org/en/content/articlelanding/2015/gc/c5gc00622h#!divAbstract))

~~~
rosser
> _Furthermore, burning rice hulls to produce electricity and RHA, generates
> more energy than required for the overall process._

I don't have access to the paper, but assuming I'm reading that correctly, the
notion of burning rice hulls to power the process and thereby source their ash
is a fantastic efficiency.

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stewbrew
The list is somewhat biased:

    
    
        Iron (from iron ore)
        [...]
        Steel (from iron)
        Paper (from standing timber)
    

Is the energy for digging up the ore or felling that tree + transport +
machinery for production included? Steel should probably also include the
numbers for iron.

The list would benefit from a common baseline. Without that these are just
random numbers.

~~~
londons_explore
I'd prefer it said:

Steel (from the things Steel is typically made from in 2019 - 80% iron ore,
50% process X, 20% recycled)

That gets tricky, because many industrial processes use large amounts of
energy, but only because that energy is effectively 'free' as waste heat from
other processes.

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kensai
The original article is also interesting:
[https://www.lowtechmagazine.com/2009/06/embodied-energy-
of-d...](https://www.lowtechmagazine.com/2009/06/embodied-energy-of-digital-
technology.html)

"The 180 watt laptop

While these reports are in themselves reason for concern, they hugely
underestimate the energy use of electronic equipment. To start with,
electricity consumption does not equal energy consumption. In the US, utility
stations have an average efficiency of about 35 percent. If a laptop is said
to consume 60 watt-hours of electricity, it consumes almost three times as
much energy (around 180 watt-hour, or 648 kilojoules).

So, let's start by multiplying all figures by 3 and we get a more realistic
image of the energy consumption of our electronic equipment. Another thing
that is too easily forgotten, is the energy use of the infrastructure that
supports many technologies; most notably the mobile phone network and the
internet (which consists of server farms, routers, switches, optical equipment
and the like)."

~~~
londons_explore
Gas turbine powerplants are easily in the 60% + efficiency band... Coal at 30%
is dying out in most of the western world.

Granted every fossil fueled device ever has quoted efficiency with the Lower
Heating Value, whereas the HHV is the fairest measure. The difference consists
of if you should extract energy from the humidity in the exhaust, and the
clear answer is yes.

~~~
dredmorbius
AFAIR "easily" is a stretch -- there are highly efficient combined-cycle gas-
turbine plants, and I think some of those actually get above 50% efficiency.

For most thermal generation, however, it's Carnot-cycle limits which get you
down, and that's governed by hot vs. cold side efficiency.

Coal actually has some of the _higher_ efficiencies, in some cases, exceeding
45%, though whether that's through high temps or combined cycle I'm not sure.
(I'm not defending coal, just noting efficiency numbers I've encountered.)

Update: Wikipedia's language is "possibly 62%" efficiency, FWIW:
[https://en.wikipedia.org/wiki/Combined_cycle_power_plant](https://en.wikipedia.org/wiki/Combined_cycle_power_plant)

~~~
londons_explore
You're right - only the best ones achieve 60+% efficiency.

For example, [1] achieved 63.08% efficiency at the whole-site level (ie.
including inefficiencies in startup, testing, etc. over a year)

[1]: [http://interfaxenergy.com/article/30230/chubu-electric-
plant...](http://interfaxenergy.com/article/30230/chubu-electric-plant-has-
worlds-most-efficient-ccgt)

~~~
dredmorbius
Thanks.

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mikestew
I'm going to have to cut down on my titanium addiction. OTOH, my nephew's
grandchildren will be fighting over that double-walled coffee mug long after I
die.

~~~
jsilence
Gather the good stuff while energy is still cheap!

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Waterluvian
Recycle your aluminum, people!

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femto
This paper also adds information on absolute energy usage and per kilogram
produced.

[http://web.mit.edu/ebm/www/Publications/energy_required.pdf](http://web.mit.edu/ebm/www/Publications/energy_required.pdf)

~~~
Gibbon1
I've found this paper tantalizing.

[https://www.researchgate.net/publication/222566309_Electrowi...](https://www.researchgate.net/publication/222566309_Electrowinning_of_iron_from_sulphate_solutions)

""High purity iron was produced, with a current yield of 85% and a power
consumption of 4.25 kWh/kg iron.""

If you run numbers you get energy costs of about $400-$500/ton.

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edejong
Would be nice to contrast this with the energy necessary to produce 1 kilogram
of various foodstuffs.

~~~
dredmorbius
[https://www.treehugger.com/green-food/energy-required-to-
pro...](https://www.treehugger.com/green-food/energy-required-to-produce-a-
pound-of-food.html)

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dvh
Is electronic grade silicon created by chemical vapor deposition? I thought
czochralski process.

~~~
BostonEnginerd
It's both, I believe. Highly purified polysilicon is created using the Siemens
CVD process. This is then broken up and used as feedstock for a CZ crystal
puller.

------
dredmorbius
For those seeking sources for embodied energy, ICE seem to be among the more
rigorous and accepted sources (I've encountered them before).

Wikiedia cites similar values referencing ICE.

[http://www.circularecology.com/embodied-energy-and-carbon-
fo...](http://www.circularecology.com/embodied-energy-and-carbon-footprint-
database.html)

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

------
quixoticelixer-
Does the value from wood come from processing it or does it include the energy
the tree used to make it?

~~~
rebuilder
It says "From standing timber", so I'd say that's the energy used in
processing, whatever that is defined as.

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JKCalhoun
I understand we put aluminum recycling plants near rivers (like the Columbia)
where energy costs is cheap.

~~~
deepsun
Or the other way around. In USSR, at least, few power plants were built closer
to aluminum ore deposits.

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ahigherugliness
Is measuring in kilograms a good way to think about this? How many kilograms
of chips does my phone have?

~~~
dredmorbius
It normalises the metric across all levels of production. Scale according to
use.

A 5" iPhone weighs 138g. Much of that is probably battery, display, and case,
so chips are on the order of 10% or less of the total. I'd estimate at <10g.

The core processor is the A10 Fusion SoC, 125mm^2, probably a few mm thick.
Silicon has a density of 2.3290 g/cm^3. That adds up to about 20-30g,
depending on thickness, though I'm not sure of the density or thickness of a
silicon wafer. I suspect actual mass is less.

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philipkglass
Numbers are not sourced and, in at least some cases, suspiciously high. Virgin
aluminum is more like 14 kWh/kg, not 63.

[https://www.iea.org/tcep/industry/aluminium/](https://www.iea.org/tcep/industry/aluminium/)

~~~
8bitsrule
The OP-linked page points to a source URL at the bottom (An MIT
'Environmentally Benign Manufacturing' bibliography).

[http://web.mit.edu/ebm/www/publications.htm](http://web.mit.edu/ebm/www/publications.htm)

After that URL it points back to a Low-Tech page called 'The monster footprint
of digital technology'

[https://www.lowtechmagazine.com/2009/06/embodied-energy-
of-d...](https://www.lowtechmagazine.com/2009/06/embodied-energy-of-digital-
technology.html')

For a summary graphic, see figure 2 in this cited PDF (Gutowski et.al)

[http://web.mit.edu/ebm/www/Publications/energy_required.pdf](http://web.mit.edu/ebm/www/Publications/energy_required.pdf)

~~~
philipkglass
I did refer to figure 4 in that PDF. It shows aluminum around 16 kWh/kg for
smelting. According to the accompanying pie chart, electricity used in
smelting accounts for 75% of the energy used in aluminum production while
bauxite mining, alumina refining, primary casting, and anode production
account for another 25%. Starting from 16 kWh for smelting that would put the
full energy intensity at 21 kWh per kg of aluminum.

~~~
8bitsrule
Yeah, I misread the Figure numbering in that paper, it should have been '2'
(which has a big black '4' next to it).

On the whole, and prima facie, that graphic delivers much the same message,
and rings true. Can't expect the L-T author to do -all- the work.

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mrpurple_
What about fuels like petrol? :)

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roberto
A plot here would go a long way.

~~~
dredmorbius
Comparable:
[http://www.epa.vic.gov.au/agc/resources/img/research/r_emmis...](http://www.epa.vic.gov.au/agc/resources/img/research/r_emmissions_image2.gif)

