Are virtual worlds environmentally sustainable? Based on such
thoughts, Nicholas Carr wrote a blog post some time ago, in
December 2006, about how much power we use when we use virtual worlds.
It provoked strong reactions, not the least because the title of his
text was "Avatars consume as much electricity as Brazilians".
Still years and years laters, texts (such as this one :-) about avatars,
eletricity, climate impact and Brazilians show up like a
jack-in-the-box. I will here go through Nick’s line of reasoning and the
criticism he encountered before I go on and analyze the ways in which
we can think about these issues. It would be nice to eventually come around and write about the power consumption
and carbon footprint of PCs and data centers. Computer servers consume
one percent or so of the world electricity supply. That might not sound
like much, but their power consumption grows by 15-20% per year (which
is equivalent to a fivefold increase in 10 years).
At the time when Nick Carr posted is question, the virtual world Second Life
was visited by somewhere between 10 000 and 15 000 avatars at any one
time. To run it all, no less than 4000 servers were required. In the
absence of actual figures as to the electricity consumption of the
company that runs Second Life - Linden Lab
- Nick made a few assumptions:
- Each server in Linden Lab’s data
center burns through 200 watts and then uses an additional 50 watts to
cool the data center.
- Every home computer that is connected to Second
Life uses 120 watts.
This would mean that the 4 000
servers in question use (4 000 servers) x (250 watts) x (24 hours) = 24
000 kWh (kilowatt hours) each day. Additionally, the power consumption
of all home computers is (12 500 PCs on average) x (120 watts) x (24
hours) = 36 000 kWh each day. Altogether these computers and servers
would thus use 60 000 kWh per day and if we divide this electricity
consumption between 12 500 avatars, each of them would use 4.8 kWh for
each 24 hours of existence in the game/virtual world Second Life.
much is 4.8 kWh per day then? Well, it adds up over the days and months
and becomes 1750 kWh per year which is comparable with the electricity
consumption per capita in Brazil (according to the 2003 data that Nick
had access to).
In the ensuing discussion, Nick was
quickly corrected by a person who was employed by Linden Lab.
Previously, each computer server ran a "region" in the game but now, a
server may run up to four "regions". The correct figures for Linden
Lab’s electricity consumption is therefore (1 000 servers) x (225 watts)
x (24 hours) = 5 400 kWh per day - that is, less than 1/4 of the
original estimate (which, however was based on a fuzzy statement by the
CEO of Linden Lab). The new figures gives that an avatar consumes
approximately 1 200 kWh per year instead of 1 750 kWh, and that Linden
Lab’s servers account for a relatively small part of that power
consumption while the home computers account for more than 85% of the
total power consumption.
Almost six months later
(May 2007), Nick is once more corrected when a new, better-informed (?)
employee from Linden Lab presents new figures. To begin with, the
average number of avatars are now 30 000, and the number of servers has
risen to 2 000. In addition, both servers and home PCs draw
significantly more power when the run Second Life. Now, Linden Lab’s
power consumption is instead (2 000 servers) x (500 watts) x (24 hours) =
24 000 kWh. The rule of thumb is that for every watt that a server
uses, the same amount of energy is needed to cool the data center where
the server is housed. Power consumption at home is estimated to be (30
000 computers) x (250 watts) x (24 hours) = 180 000 kWh per day. In
total, these 204 000 kWh divided into 30 000 avatars becomes 6.8 kWh per
day. That is equivalent to 2 500 kWh per year and the home computer
accounts for almost 90% of the total power consumption. Latvia, Romania
and Argentina are a few countries that had a power consumption in the
neighborhood of 2 500 kWh per capita in 2005. In Sweden, we used more
than 15 000 kWh per person in 2005.
Taking all of this conflict (and constantly changing) information into account, what conculsions can be drawn so far?
The Internet changes constantly. To get current figures is like chasing
a moving target. What are the figures for Second Life right now?
According to the latest figures (Jan 2010) there are currently 18 million accounts (avatars) registered in Second Life, but only 750 000 of them (5%) log in to Second Life each month. These avatars spent a total of 118 million hours (!) in Second Life during the third quarter of 2009.
Information about the number of servers and their power consumption
varies widely and therefore seems not be that reliable (see above).
Power consumption can obviously not have been one of the heavier costs
when running virtual worlds - or they would have kept better track of
the figures. The same has probably been true also for other companies
that rely on data centers such as Google, Flickr, Blizzard etc., but
things might be changing now as the energy prices have been marching
upwards during the last couple of years.
- A computer
at work uses 120-150 watts, but a computer that runs Second Life (or
World of Warcraft or any other computer games) can use up to twice as
much power as these applications make use of your computer's
capabilities to the max. Data center use a lot of power, but you home
computer that utilizes these services draw a lot more and get less work
(computer cycles) done per unit of energy used.
is difficult to determine the usefulness (or damage) of using virtual
worlds. On the one hand, you use a lot less energy (and generate
considerably less pollution) if you cancel a trip and instead meet in a
virtual world. But a computer uses a lot of electricity - if the option
is an electricity-free activity (take a walk, talk to a neighbor, help
your children do their homework).
- Ideas are hard to kill. Although Nick’s figures were refuted and modified immediately, the "meme" about Second Life and the electricity consumption of Brazilians remains alive and pops up now and then to the chagrin of some.
main objections raised against Nick’s argument above was that no real
person is connected to Second Life 24 hours a day and that Second Life
actually had 700 000 "active user" (whatever that means) at the time. So
the power consumption of each person who used Second Life would have
been just a 50th of Nick’s original calculation. Furthermore, any
computer that is used for 24 hours a day 365 days per year uses more
energy than the average Brazilians whatever that computer is used for
(playing Second Life or doing something entirely different).
ways of looking at this problem is correct, but these different
perspectives choses to focus on slightly different things. Any
individual physical person who plays Second Life did that for less than
an hour a day on average and thus uses a moderate amount of energy. But
each avatar in Second Life has the same (or higher) power consumption
(per hour, per day or per year) as many people on earth have.
think Nicholas perspective is interesting, not the least because some
information technology pundits sometimes tend to completely ignore that
computers are physical objects that have required resources (raw
materials, energy) for their manufacture, that consume electricity
throughout their lifetime, and that one day will be scrapped/recycled.
Computers obviously have an ecological footprint and the size of that
footprint should naturally be explored further.