> How many joules go into producing those 900 calories? I think what you're getting at is question about conversion efficiencies, from solar radiation to whate

> How many joules go into producing those 900 calories? I think what you're getting at is question about conversion efficiencies, from solar radiation to whatever the computing-machine needs. However, your description seems to risk double-counting things: You can't just sum up the inputs of each step, because (most of) the same energy is flowing onwards.