Embodied energy of digital technology
lowtechmagazine.com
lowtechmagazine.com
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.
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.
Rice hulls cost something to produce too, and I bet you need a lot more than a kilo of them to make a kilo of silicon...
Alternative sourcing: https://www.sciencedirect.com/topics/engineering/embodied-en...
(Hits: timber, recycled and stainless steel, aluminium, glass, plastics.)
Enough so that I'd be inclined to believe the values. Low Tech Magazine is generally reliable in my experience.
"smell about right"
"spot checks suggest they're reasonable"
"generally reliable in my experience"
Iron (from iron ore)
[...]
Steel (from iron)
Paper (from standing timber)
The list would benefit from a common baseline. Without that these are just random numbers.
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.
There's a tremendous variability to industrial processes and material utilisation, including virgin vs. recycled materials. Listing from among options may help clarify engineering / manufacturing / consumption values and choices.
"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)."
While I agree with you, it's worth noting that the server farms of our tech giants are already powered by renewable energy (Google 100%, AWS 50%, Microsoft 50%, ...).
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.
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
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...
https://www.researchgate.net/publication/222566309_Electrowi...
""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.
Wikiedia cites similar values referencing ICE.
http://www.circularecology.com/embodied-energy-and-carbon-fo...
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.
The other paper posted by femto shows aluminum at ~16 kWh/kg. The slightly higher value is due to an earlier date cutoff around 2009. See figure 4(b):
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...
For a summary graphic, see figure 2 in this cited PDF (Gutowski et.al)
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.
Maybe to get the 63 kWh/kg figure, you add to the 14 kWh/kg figure the energy needed to collect the cans (if recycled) and to mine the aluminum (if not) and the energy needed to build the refining or recyling plant and the energy used by the workers who mine, collect and operate the refining and recycling plants, including the energy used to feed, clothe, educate, entertain, transport, etc, the workers.
In other words, maybe one figure attempts to estimate the second- and third-order energy use, i.e., the "total carbon footprint", and the other does not.
As Sagan might not have Said:
If you want to make a kilo of virgin aluminium, you must first invent the global economy.
Paying it forward, here is the original clip so others can get a hit of the sweet sweet nostalgia...