If a car is 100x the embedded energy and lasts 5x as long, then the car takes 20x as much energy per useful year. This doesn't count the energy to run each of them, which is more lopsided obviously.
So, I managed to goof the account above a few ways.
First, cars weigh 10,000 times, not 1,000 times, more than a cellphone.
Embodied (not embedded) energy is 100x greater for the automobile.
The units produced annually is a major factor: 2 billion for mobile phones, 72 million for automobiles. That plus product life skews the number toward phones a lot.
I did manage to get the bottom-line value right: autos use 0.72 exajoules of energy per year of use, 30% less than mobile phones.
A longer version of the example was published in IEEE Spectrum in 2016:
Interesting article, thanks for posting! A few things to add.
Your article actually says that cars use 7x as much embodied energy as devices, (7 to 1), but then corrects both for lifetime (10 and 2 years), thus you get 0.5 vs 0.7 for devices vs cars respectively, not 1 vs 0.7.
The article then concludes cars use 40% more embedded energy than all devices on the planet, not 30% less.
Then, we're talking about phones here, the article about devices, including 60 million laptops which the article assumes use 18x the embodied energy of a phone. i.e., next to the 1.9 billion phones, the article essentially adds in 1.08 billion phone-equivalent laptops, which carry a worse energy/mass ratio, but aren't adjusted for a much better lifetime than 2 years average. Same for smartphones, btw. The article leaves out embodied energy of cars and just assumes a car to perform without any repairs or maintenance for 10 years, like a phone does for 2 years.
It also doesn't really explicitly mention the context which is that it's a comparison is between more than 2 billion devices servicing an approximately similar amount of humans, vs 72 million vehicles.
The article does mention that a phone's energy use in 2 years would add, at most, 8% to its embodied energy, for an indexed figure of 1.08. A car uses 5x as much of its embodied energy, for a total figure of 6x. Again, this is without figuring in maintenance. In short, for a real impact figure you'd multiply the 0.72 by 6, and you end up with energy to 72m cars using more than 8x as much energy than 2 billion smartphones and more than a billion phone-equivalent laptop/tablet devices, at minimum.
The book and article differ on the 30% / 40% point, and Smil is IMO not entirely clear here (or I'm up too late reading this).
The general upshot is that silicon is very energy-intensive stuff -- to manufacture, and to operate. Several authors (including Smil) have noted that the highest energy use densities, in terms of watts per unit-mass of equipment, are seen in information systems. There's a reason for all those massive cooling systems at datacentres.
(And yes, I've just shifted the discussion from embodied energy to operating energy, in the interest of the general point of energy consumption of information systems, not trying to confuse the two points, though that has been done several times already in various parts of this thread, including your own response above.)
That density still doesn't necessarily imply greater total energy use, though it starts getting you that way.
As for transport vs. information: a further point to consider is that there are constraints on moving people around in a physical environment, imposed by mass, air, rolling resistance, and braking (or regen) losses. We're relatively close -- definitely within an order of magnitude, and possibly a power or so of two, to those limits. For information, the theoretical efficiencies are high (Feynman did work on this IIRC), but our technology is nowhere near that bound, and we seem quite good at throwing additional tasks and requirements on our computing systems as efficiency improves. (This is also true of transport -- both are subject to the Jevons paradox.)
This also gets us to a sort of Amdahl's Law problem: as the operational energy of computers falls, the embodied energy costs seem to increase and become a larger portion of the overall expense. Since the operating cost == marginal cost, this also means that market dynamics alone, which function based on marginal costs, are exceedingly unlikely to discourage this trend. It's another zero-marginal-cost dynamic (see Jeremy Rifkin's recent book).
Smil has a great deal of expertise and experience here, his writing is usually pretty clear, and I'm inclined to credit his claims. Though I may need to evaluate this particular one more closely. Though at some time when my neurons are not in isolation cells....
These calculations are pretty hard since cars are all different and so are phones. We do know that the auto industry is about 1.7 trillion dollars per year, and the phone market is about 500 billion. This suggests to me that autos are likely more. In total lifecycle though the energy used by autos is far far greater than by phones as well.
Thanks for the education; that's a useful concept.
> Embodied
Do you mean "embedded"? I'm not nitpicking; I want to make sure I understand.
Where does one find the embedded/embodied energy for a product? I'd be surprised if it can be calculated - the energy required to mine, transport, manufacture, dispose every bit of every raw material that eventually goes into all the parts of an automobile (or other complex modern device)? It would be a very valuable but daunting task. How is it done and who does it?
