In one of John Thackara's Doors of Perception reports, I came across the concept of digital devices as "embodied energy." The term is used by Kris De Decker in a piece on "the monster footprint of digital technology," and it's intended to call attention to the very large amount of energy that is consumed during the manufacturing of electronics. But it also is a data-point in how we no longer think of digital devices as portals to another world, but rather think more about their connections to this one.
The energy used to produce electronic gadgets is considerably higher than the energy used during their operation. For most of the 20th century, this was different; manufacturing methods were not so energy-intensive.
An old-fashioned car uses many times more energy during its lifetime (burning gasoline) than during its manufacture. The same goes for a refrigerator or the typical incandescent light bulb.... Advanced digital technology has turned this relationship upside down. A handful of microchips can have as much embodied energy as a car. And since digital technology has brought about a plethora of new products, and has also infiltrated almost all existing products, this change has vast consequences.
Not only do electronics use more energy in manufacturing than in use, they require a LOT more energy per unit of material to manufacture.
[W]hile the ratio of fossil fuel use to product weight is 2 to 1 for most manufactured products (you need 2 kilograms of fuel for 1 kilogram of product), the ratio is 12 to 1 for a computer (you need 12 kilograms of fuel for 1 kilogram of computer). Considering an average life expectancy of 3 years, this means that the total energy use of a computer is dominated by production (83% or 7,329 megajoule) as opposed to operation (17%). Similar figures were obtained for mobile phones....
The energy needed to manufacture microchips is disproportional to their size. MIT-researcher Timothy Gutowski compared the material and energy intensity of conventional manufacturing techniques [machining, injection molding and casting] with those used in semiconductor and in nanomaterial production (a technology that is being developed for use in all kinds of products including electronics, solar panels, batteries and LEDs).... While there are significant differences between configurations, all these manufacturing methods require between 1 and 10 megajoule of electricity per kilogram of material. This corresponds to 278 to 2,780 watt-hour of electricity per kilogram of material. Manufacturing a one kilogram plastic or metal part thus requires as much electricity as operating a flat screen television for 1 to 10 hours (if we assume that the part only undergoes one manufacturing operation).
The energy requirements of semiconductor and nanomaterial manufacturing techniques are much higher than that: up to 6 orders of magnitude (that's 10 raised to the 6th power) above those of conventional manufacturing processes (see figure below, source, supporting information). This comes down to between 1,000 and 100,000 megajoules per kilogram of material, compared to 1 to 10 megajoules for conventional manufacturing techniques.
It would be interesting to compare the amount of intellectual energy that goes into the design of, say, a car versus a microchip. I've long thought of digital devices as being knowledge-intensive and resource-light-- a laptop computer embodies a lot more intelligence than an iron bar-- but this has always been a conceptual thing, not something that I tried to measure.
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