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The monster footprint of digital technology
The power consumption of our high-tech machines and devices is hugely underestimated.
we talk about energy consumption, all attention goes to the electricity
use of a device or a machine while in operation. A 30 watt laptop is
considered more energy efficient than a 300 watt refrigerator. This may
sound logical, but this kind of comparisons does not make much sense if
you don't also consider the energy that was required to manufacture the
devices you compare. This is especially true for high-tech products,
which are produced by means of extremely material- and energy-intensive
manufacturing processes. How much energy do our high-tech gadgets
Artwork: cityscape I & II by Grace Grothaus.
energy consumption of electronic devices is skyrocketing, as was
recently reported by the International Energy Association ("Gadgets and gigawatts").
According to the research paper, the electricity consumption of
computers, cell phones, flat screen TV's, iPods and other gadgets will
double by 2022 and triple by 2030. This comes down to the need for an
additional 280 gigawatts of power generation capacity. An earlier
report from the British Energy Saving Trust (The ampere strikes back - pdf) came to similar conclusions.
There are multiple reasons for the growing energy consumption of electronic equipment; more and more
people can buy gadgets, more and more gadgets appear, and existing
gadgets use more and more energy (in spite of more energy efficient
technology - the energy efficiency paradox described here before).
The 180 watt laptop
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).
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).
important, however, is the energy required to manufacture all this
electronic equipment (both network and, especially, consumer appliances). 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
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:
the energy required to manufacture the product pales into
insignificance when compared to the energy used during its operation.
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. Present-day cars and since long
existing analogue devices are now full of microprocessors.
Semiconductors (which form the energy-intensive basis of microchips)
have also found their applications in ecotech products like solar
panels and LEDs.
Where are the figures?
While it is fairly easy to obtain figures regarding the energy
electronic devices during the use phase (you can even measure it yourself using a
power meter), it is surprisingly hard to obtain reliable and up-to-date figures on the
energy consumed during the production phase. Especially when it
concerns fast-evolving technologies. A life
cycle analysis of high-tech products is extremely complex and can take many
years, due to the
large amount of parts, materials and processing techniques involved. In
the meantime, products and processing technologies keep evolving, with the result that most
life cycle analyses are simply outdated when they are
energy consumption of a laptop during its life expectancy of 3 years
For more recent and emerging technologies, life cycle analyses simply
do not exist. Try looking for a research paper that calculates the
embodied energy of
a Light Emitting Diode (LED), a lithium-ion battery or any device full
meant to save energy: you won't find it (and if you do, please let me
Embodied energy of a computer
The most up-to-date life cycle analysis of a computer
dates from 2004 and concerns a machine from 1990. It concluded that
while 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
need 12 kilograms of fuel for 1 kilogram of computer). Considering an
average life expectancy of 3 years, this means that the total energy
of a computer is dominated by production (83% or 7,329 megajoule) as
to operation (17%). Similar figures were obtained for mobile phones.
the 1990 computer was a desktop machine with a CRT-monitor, many of
today's computers are laptops with an LCD-screen. At first sight, this
seems to indicate that the embodied energy of today's machines is lower
than that of the 1990 machine, because much less material (plastics,
metals, glass) is needed. But it is not the plastic, the metal and the glass that makes computers so
energy-instensive to produce. It's the tiny microchips, and present-day
computers have more of them, not less.
100 years of manufacturing
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 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).
As an example of more conventional manufacturing methods,
calculated the energy requirements of machining, injection molding and
casting. All these techniques are still used intensively today, but
they were developed almost 100 years ago. Injection molding is used for
the manufacture of plastic
components, casting is used for the manufacture of metal components,
and machining is a material removing process that involves the cutting
of metals (used both for creating and finishing products).
6 orders of magnitude
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).
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
megajoules per kilogram of material, compared to 1 to 10 megajoules for
conventional manufacturing techniques.
one kilogram of
electronics or nanomaterials thus requires between 280 kilowatt-hours and 28
megawatt-hours of electricity; enough to power a flat screen television
continuously for 41 days to 114 years. These data do not include
facility air handling and environmental conditioning, which for
semiconductors can be substantial.
Embodied energy of a microchip
The energy consumption
of semiconductor manufacturing techniques corresponds
with a life cycle analysis of a "typical" 2 gram microchip
performed in 2002. Again, this concerns a 32 MB RAM memory chip - not
really cutting edge technology today. But the results are
nevertheless significant: to produce the 2 gram microchip, 1.6
kilograms of fuel were needed. That means you need 800 kilograms of
fuel to produce one kilogram of microchips, compared to 12 kilograms of
fuel to produce one kilogram of computer.
we take the energy density of crude oil (45 MJ/kg), this comes down to
72 megajoules (or 20,000 watt-hour) to produce a 2 gram microchip. Converted to a one kilogram microchip this comes down
to 3.3 megawatt-hours of electricity (or 36,000 MJ), well within the range of
the 280 kilowatt-hours (1,000MJ) and 28 megawatt-hours (100,000 MJ) calculated
Also, the International Technology Roadmap for Semiconductors 2007 edition
gives a figure of 1.9 kilowatt-hours per square centimetre of microchip, so 20 kilowatt-hours
per 2 gram, square centimetre computerchip seems to be a reasonable
How many microchips in a computer?
gadget or a computer does not contain one kilogram of semiconductors -
far from that. But, we don't need a kilogram of microchips to ensure
that the manufacturing phase will largely outweigh the usage phase. The
embodied energy of the memory chip alone already exceeds the
energy consumption of a laptop during its life expectancy of 3 years.
Today's personal computers have a RAM-memory of 0.5 to 2 gigabyte modules that
typically consist of 18 to 36 two-gram-microchips (as the ones
described above). This equates to 1,296 to 2,595 megajoules of embodied energy for the
computer memory alone, or 360,000 to 720,000 watt-hour. Enough to power
a 30 watt laptop non-stop for 500 to 1,000 days.
(the "brains" of all digital devices) are more advanced than memory
chips and thus contain at least as much embodied energy. Unfortunately,
no life cycle analysis of a microprocessor has been published. Certain
is that modern computers contain ever more of them.
One trend in recent years is the introduction of "multicore
processors" and "multi-CPU systems". Personal computers can now contain 2, 3
or 4 microprocessors. Servers, game consoles and embedded systems can
have many more. Each of these "cores" is capable of handling its own
task independently of the others. This makes it possible to run several
CPU-intensive processes (like running a virus scan, searching folders
or burning a DVD) all at the same time, without a hitch. But with every extra chip (or chip surface) comes more embodied energy.
Another trend is the rise of the "Graphics Processing Unit" or GPU.
This is a specialised
processor that offloads 3D graphics rendering from the microprocessor.
The GPU is indispensable to play modern
videogames, but it is also needed because of the ever higher
graphical requirements of operating systems. GPU's do not only raise
the energy consumption of a
computer while in use (GPU's can consume more
energy than current CPU's), but they also stand for more embodied
energy. A GPU is very memory-intensive and thus also increases the need
for more RAM-chips.
Why are microchips so
energy-intensive to manufacture? One of the reasons becomes clear when
you literally zoom in on the technology. A microchip is small, but the
amount of detail is fabulous. A microprocessor the size of a fingernail
can now contain up to two billion transistors - each transistor less
than 0.00007 millimetres wide. Magnify this circuit and it becomes a
structure as complex as a sprawling metropolitan city.
amount of materials embedded in the product might be small, but it
takes a lot of processing (and thus machine energy use) to lay down a
complex and detailed circuit like that. While the electricity
requirements of machines
used for semiconductor manufacturing are similar to those used for
older processes like injection molding, the difference lies in the
process rate: an injection molding machine can process up to 100
material per hour, while semiconductor manufacturing machines only
materials in the order of grams or milligrams.
why digital technology is so energy-intensive to manufacture is the
need for extremely effective air filters and air circulation systems
(which is not included in the figures above). When you build
infinitesimal structures like that, a speck of dust would destroy the
circuit. For the same reason, the manufacture of microchips requires
the purest silicon (Electronic Grade Silicon or EGS, provided by the
as the manufacture of microchips.
Every 18 months the amount of transistors on a microchip doubles
(Moore's law). On one hand, this means that less silicon is needed for
a certain amount of processing power or memory. On the other hand, when
transistors become smaller, you need even more effective air filtration
and purer silicon. Since the structure also becomes more complex, you
need more processing steps.
Nanotechnology operates on an even smaller scale than
micro-electronics, but its energy requirements are comparable. Carbon
nanofiber production, which is based on many of
the same techniques used by semiconductor manufacturing, requires 760
to 3,000 MJ of electricity per kilogram of material, while carbon nanotubes and single-walled
nanotubes (SWNTs) manufacturing requires a hefty 20,000 to 50,000 MJ
per kilogram. The manufacture of nanotubes is thus as energy-intensive
as the manufacture of microchips (36,000 MJ). Many of the large-scale applications proposed for nanotubes will simply not be possible because of energy requirements.
Recycling is no solution
Encouraging recycling is
often proposed as a way to lower the embodied energy of products.
Unfortunately, this does not work for micro-electronics (or nanomaterials). In
the case of conventional manufacturing methods, the energy requirements
of the manufacturing process (1 to 10 MJ per kilogram) are small
compared to the energy required to
produce the materials themselves.
For instance, producing 1 kilogram of
plastic out of crude oil requires 62 to 108 MJ of energy, while a
typical mix of virgin and recycled
aluminum requires 219 MJ. To make a fair comparison, you have
multiply the energy requirement of the manufacturing process by three
(1 megajoule of electricity requires 3 megajoules of energy) but even
then (with 3 to
30 MJ/kg) conventional manufacturing
processes appear to be quite benign compared to materials extraction
and primary processing (in the order of 100 MJ/kg - see table).
manufacturing process itself.
the case of semiconductor manufacturing, this relation is reversed.
While it takes
230 to 235 MJ of energy to produce 1 kilogram of silicon (already quite
high compared to many other materials), chemical vapour deposition
(an important step in the semiconductor manufacturing process) requires
about 1,000 MJ of electricity and thus 3,000 MJ of energy per
That is 10 times more than the energy consumption of material
extraction and primary processing. In the case of conventional
manufacturing techniques, the use of
recycled material is an effective way to lower overall energy use
during manufacture. In the case of semiconductors, it is not. Recycling is not a solution
for energy consumption if all your energy use is concentrated in the
This does not mean that the manufacture of microchips does not
require materials. In fact, producing microchips and nanomaterials is
also more material
intensive than the manufacture of conventional products, by the same
orders of magnitude. However, this concerns auxiliary materials which
are not incorporated into the product.
For example, the embodied energy of the
input cleaning gases in the CVD process (not included in the figures above) is more than 4 orders of magnitude greater
than that of the product output. Furthermore, these gases have to be
treated to reduce their reactivity and possible attendant pollution.
Gutowski writes: "If this is done using point of use combustion with methane,
the embodied energy of the methane alone can exceed the electricity
The benefits of digital technology
Microchips also have positive effects on
the environment, by making other activities and processes more
efficient. This is the subject of a publication by the Climate Group,
an initiative of more than 50 of the world's largest companies. The report ("Smart 2020 - enabling the low carbon economy in the information age")
confirms the findings of other studies regarding the electricity use of
electronic equipment, but also calculates the benefits.
to Smart 2020, the emissions from Information and Communications
Technology (including the energy use of data centres, which the IEA
report does not include) will rise from 0.5 Gt CO2-equivalents in 2002
to 1.4 GtCO2-equivalents in 2020, assuming that the sector will
continue to make the "impressive advances in energy efficiency that it
has done previously". By enabling energy efficiencies in other sectors,
however, ICT could deliver carbon savings 5 times larger: 7.8 Gt
CO2-equivalents in 2020.
approach to lower the ecological footprint of digital technology
These benefits are smart grids (2.03
Gt), smart buildings (1.86 Gt), smart motor systems (970 Mt),
dematerialisation and substitution (by replacing high carbon physical
products and activities such as books and meetings - with virtual low
carbon equivalents such as electronic commerce, electronic government,
videoconferencing, 500 Mt) and smart logistics (225 Mt). One of the
first tasks of ICT will be to monitor energy consumption and emissions
across the economy in real time, providing the data needed to optimise
for energy efficiency.
The report concludes: "The scale of
emission reductions that could be enabled by the smart integration of
ICT into new ways of operating living, working, learning and
travelling, makes the sector a key player in the fight against climate
change, despite its own growing footprint."
But even if we
assume that all these savings will materialise (the report acknowledges
that this will not be an easy task), this conclusion does not take into
account the energy needed to manufacture all this equipment. If we
assume the share of manufacture to be 80 percent of
total energy consumption by ICT (following the only life cycle analysis of a
computer we have), then the 1.4 Gt in 2020 in reality should be 7 Gt -
almost as much as the 7.8 Gt that will be saved by ICT. No
environmental benefit would appear and the energy savings realised by
digital technology would merely absorb its own growing footprint.
Digital technology is a product of cheap energy
research of Timothy Gutowski shows that the historical trend is toward
more and more energy intensive processes. At the same time, energy
resources are declining.
phenomenon has been enabled by stable and declining material and energy
prices over this period. The seemingly extravagant use of materials and
energy resources by
many newer manufacturing processes is alarming and needs to be
addressed alongside claims of improved sustainability from products
manufactured by these means."
Production techniques for
semiconductors and nanomaterials can and will become more efficient, by
lowering the energy requirements of the equipment or by raising the
operating process rate. For instance, the "International Technology Roadmap for Semiconductors" (ITRS), an initiative of the largest chip manufacturers worldwide, aims to lower energy consumption
(pdf) per square centimetre of microchip from 1.9 kWh today to 1.6 kWh in
2012, 1.35 kWh in 2015, 1.20 kWh in 2018 and 1.10 kWh in 2022.
as these figures show, improving efficiency has its limits. The gains
will become smaller over time, and improving efficiency alone will
never bridge the gap with conventional manufacturing techniques.
Power-hungry production methods are inherent to digital technology as
we know it.
The ITRS-report warns that:
"Limitations on sources of energy could potentially limit the
industry's ability to expand existing facilities or build new ones".
"It should be pointed out that there is also a need for
completely rethinking each of these processes and exploring
alternative, and probably non-vapour-phase processes".
The ecological footprint of digital technology described above is far
from complete. This article focuses exclusively on energy use and does not take
into account the toxicity of manufacturing processes and the use of
water resources, both of which are also
several orders of magnitude higher in the case of both semiconductors and nanomaterials. To give an idea: most water used in semiconductor manufacturing is
ultrapure water (UPW), which requires large additional quantities of
chemicals. For many of these issues, the industry recognizes that there are no solutions (see the same ITRS-report, pdf). There are also the problems of waste & war.
but not least: the energy-intensive nature of digital technology is not
due only to energy-intensive manufacturing processes. Equally as
important is the extremely short lifecycle of most gadgets. If digital
products would last a lifetime (or at least a decade), embodied energy
would not be such an issue. Most computers and other electronic devices
are replaced only after a couple of years, while they are still
perfectly workable devices. Addressing technological obsolescence would
be the most powerful approach to lower the ecological footprint of
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