How Much Water is Used to Download a Song?

Yesterday, I asked my wife what she thought about my previous post about Google's energy use. She said it was alright, except that it didn't have anything to do with water. Many times she does have a case, but I thought I would revisit this idea today since energy has everything to do with water.

THE ENERGY-WATER NEXUS TRUTH: Energy is required to make use of water and water is needed to make use of energy.

Here is a simple example. How much water would you think is consumed when you download a song from iTunes?

My not-so-scientific assumptions:

• Internet Fuel Rating: 1 lb of coal per 2MB of Data (From Forbes Article Dig More Coal)
• iTunes Song Size: 4MB
• Coal Fuel Efficiency : A 500 MW plant uses 250 tons of coal per hour & uses 12 MGD (.5 million gallons/hr) of cooling water (DOE Study)
• Assuming a coal plant's cooling facilities recycles 80% of the water, only 20% of the water is actually used or evaporated.

Although this is a bit early in the morning for math even for me, I calculated that a half gallon of water is consumed to download a song if all the energy comes from a coal plant. Is this surprising? It was to me. Just think how much water has been consumed when Apple said this past summer that 3 billion songs had been downloaded from iTunes.

How is this for a new nationwide water conservation campaign?

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