Mr. Palmer, a UK physics tutor, has many of his physics lectures for General Certificate of Secondary Education (GCSE) online, with notes and illustrations. You can find topics such as “motion”, “heat”, “nuclear radiation”, and even “the origins of the universe”. Very infomative, and well illustrated, even if you are not a high school student.
To attract student’s interest and make them understand efficiency in the “electricity” topic, he asks them to draw a Sankey diagram for their iPod.
The three Sankey diagram examples Mr. Palmer shows in his notes use the simple but effective grid paper approach that I have shown in this post.
I have tried to get to the numbers behind the diagram, but even in the tech specs, in the product environmental report for the iPod and on Apples environment website, they don’t give details on how much of the power is used for screen lighting and sound, and how much is lost as heat. So I guess that Mr. Palmer might have made these up, and that the energy efficiency of 31% for the iPod is just an arbitrary number…
Even though I didn’t find the hard facts, I came across some ideas and fancy gadgets for the iPod, that make its use “greener”, even though they do not increase the energy efficiency of the appliance itself:
And of course there are several hints, that help to really reduce energy consumption and make your iPod more energy efficient, such as dimming the display and avoiding to do a skip search on titles.