Downloading vs. Renting from an environmental standpoint

...or Al Gore vs. the MPAA.

This was an interesting source of in-the-shower calculations for me today. I was trying to come up with a quick comparison of the energy costs of downloading a movie vs. renting one.

I wanted to start with a real simple comparison, and expand from there if it was interesting, so here's what I did.

I had a feeling it was much more efficient to move information as electricity than to physically transport it, so I thought I had better stack the deck in renting's favour.

On the renting side:
I assumed you had a car that could consistently get 4l per hundred kilometers (that's how they measure it in Canada, it's about 58.8 mpg), at least on the trip to the video store.
I assumed the video store was fairly close by, at 2.5 kilometers.
I assumed two return trips to the video store would be required, to rent and return the video.
So this worked out to .4l of gasoline to rent a video. (2.5 * 4 = 10 kilometers, 100/10 = 0.1, 0.1 *4 = 0.4).
I put the cost of a liter of gasoline at $0.90.
This worked out to an energy cost of $0.36 to rent a movie. I figured that's pretty good.

On the downloading side:
I assumed it would take you 12 hours to download a movie.
I assumed your computer would consume an average of 100 watts during those 12 hours.
So you would consume 1200 watt-hours downloading a movie.
In the shower, I assumed $0.25 per kilowatt hour, but looking online, it seems like it's more like $0.11 per kilowatt hour.
This worked out to an energy cost of $0.14 to download a movie. That blows renting away.

So simply in terms of reducing personal energy consumption, downloading is far more effective than renting, even when we stack the deck on renting's behalf.

If we were to try to average things out a little bit (based on my personal experience), and adjust our figures thusly:
8l per 100 kilometer (29.4 mpg) car
Video store 5km away
Liter of gasoline $1.00
4 hours to download a movie
50 watts per hour

The comparison becomes $1.60 to rent, and $0.03 to download. It's nearly 50 times more energy efficient for me to download a movie than it is for me to rent one.

Now, imagine I download using my Wii, or a bit-torrent enabled router. That could easily drop energy consumption into the 15 watt range. Now lets hook me to fiber at 100 mb/s (mmm, fiber), and I can download that movie in 56 seconds (assuming my hard drive can write at 12.5 MB/sec). So it could take about 0.25 watt hours to download, or about $0.00003 in energy costs.

Obviously, there's a huge number of contextual factors left out of this equation, on both the download side (power required by the internet itself), and the driving side (production, distribution, warehousing, etc.). However, I would suspect that those factors would tilt towards downloading as well. Driving might pick up a few points as we transition to higher-resolution video.

The equation becomes even more one-sided for other types of media, such as Books or CDs.

I think the bottom line is that non-electronic distribution of practically any type of information tends to be wasteful, and isn't something that we can afford to continue.