It is always amazing to me how seemingly small things create big problems once taken to web-scale. One example is spam email. McAfee conducted a global study on how much energy is spent creating, storing, viewing and filtering the annoying spam email. First of all, the numbers are staggering: Various sources estimate that 90% of all incoming email is undesired (spam). A study lists the volume of spam email in August 2010 as 200 billion per day. Yes, that is per day. Emails that need to be sent, stored, filtered, viewed and purged. That's crazy!
Per year, according to McAfee this adds up to an energy consumption of 33 billion kilowatt-hours (kWh), or 33 terawatt hours (TWh). That’s equivalent to the electricity used in 2.4 million homes, with the same GHG emissions as 3.1 million passenger cars using 2 billion gallons of fuel. What a useless waste of energy!
Another interesting aspect is that most of the energy is consumed by end users trying to get rid of the junk mail. McAfee argues that a good spam filter can minimize this energy use and hence be a meaningful green contribution. I think this is an interesting example of using a green case study to drive additional value to the product sold. This could also be very relevant in a SaaS applications setting.