Spam costs $3 billion a year in wasted electricity alone

My previous blog post on the hidden costs of computing -- which pointed to a study that said that leaving computers on overnight wasted $2.8 billion of electricity a year -- was hotly contested by readers, many of whom felt the time spent rebooting their computer every morning was a far greater waste of money.

That remains open for debate, but here's a statistic that I think everyone can get behind: Spam wastes even more electricity than leaving your computer running 24/7, costing roughly $3 billion a year in wasted power alone.

McAfee calculated that sending, routing, and otherwise dealing with spam eats up a total of 33 billion kilowatt-hours of electricity each year. As The Guardian notes, that's enough to power 2.4 million American homes and, by my math (as the average kw-hr costs about a dime), a total cost of over $3 billion.

And that doesn't even take into account money spent on spam filtering software, the loss of productivity due to users spending time deleting spam messages and finding false positives, and losses from people who get caught up in spam-based scams, either purchasing useless or undelivered products or being the victims of a spam-based crime.

The additional insights in McAfee's Carbon Footprint of Spam Report (registration required) suggest that spam transmission creates the same amount of greenhouse gas emissions as 3.1 million passenger cars using two billion gallons of gasoline each year. That's shocking.

But all is not lost: The good news is that McAfee notes that current levels of spam filtering save 135 billion killowatt-hours of electricity that would otherwise be wasted if all users and computers went unprotected from spam.