How much energy is needed to write an e-mail?


In 2013 we sent 182.9B emails, consuming 26PJ (Peta Joules). Equivalent of yearly electricity consumed in Mongolia and 1kg of matter-energy.

Every time an e-mail is written, or any sort of human-computer interaction, some amount of energy is expended. Given that in 2013 an estimate of 182.9 billion e-mails written world wide an interesting question pops up:

How much energy is needed to write an e-mail?

By energy I mean how many Joules and by needed I mean needed by the human who writes the e-mail and the computer used to write the respective e-mail. For our calculations we’ll take an e-mail length of a 100 words. I don’t know the average e-mail size, but perhaps I should ask NSA, FSB or MSS some time to get a more accurate idea.

Sending an e-mail involves e-mail servers, routers, switches and other network devices which require energy in order to function, but given that the topology of the internet is rather hard to take into account, we’ll not bother with these details. However I suspect that the infrastructure itself that is required to send a single e-mail consumes far more energy that opening up your computer and sending the e-mail.

At this moment I’m not sure if it’s even possible to calculate this accurately, but let’s try anyway and please if you find any mistakes feel free to point them out.