Last week in a talk energy guru Vaclav Smil made the claim that four cell phones equal one car in terms of embodied energy from manufacturing. This is not energy used on daily basis, nor is it a comparison of electrical energy stored in batteries; this is the energy required to fold, spindle and mutilate materials into the useful form that we call cars or cellphones.

Here is the math on the subject, however, from WattzOn. I’m sure I’m missing something — Smil is a smart guy, and while he makes many strong claims, they are almost always supported — because I get nowhere close to 1 cell phone = 0.25 cars in embodied energy terms.

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Huh? Counting orders of magnitude your equivalency looks out of whack to me.

I get cell phone = .036car on an annualized basis

(total embedded joules of cell phone/2 years)/(total embedded joules of car/20 years)

I'm open to correction on this!

>Huh? Counting orders of magnitude your equivalency looks out of whack to me.

Whoops, *his* equivalency, I apologize for misattribution.

I see the "manufacturing" line for cell phones, but not for cars. It looks as though for cell phones WattzOn is giving us something like energy used in assembly, not embedded in the components.

No worries, assuming you were blaming me

Well, are you counting taking the bus to wait in line at the APPLE store?

Ok, a cell phone has 10% the lifespan of a car (here anyway, but who keeps a car 20 years or a cell phone 2?), so maybe you have to multiply the cell phone watt/print by 10 to get 67K watts. Then you multiply that by 4 to get 250Kish watts. So that number approximately works.

-XC

The ratio of the two energy costs is:

424054200/118284466000 = 0.0036 = 0.35%

given the shorter lifespan of cell phones (1/10), we get that the energy ratio is 3%