Inspired by this thread about what is possibly the Dope’s longest running inside gag, I got to wondering (and nearly posting in GQ but thought better of it).
Let’s say we were serious about getting the server running on hamster power - would it be possible? How many hamsters would we need? Could one of the technical Dopers assist here? We’d no doubt need a good battery unit as hamsters are intermittent power. Would it just be huge bank of hamster wheels > tiny generators > battery > power supply > server? Or am I missing something here? Hundereds of hamsters? Thousands?
Well, these guys estimate a maximum output of about 0.4 watts (200 mA at 2 V) for one hamster on a wheel with a custom-made low-RPM generator. How much power does the SDMB’s servers draw?
Heck, assuning 100% conversion efficiency (I know, I know), it would thus take 212 hamsters to power my laptop. At a more real-world estimate of 50% conversion efficiency, it would be more like 425.
Here’s a PDF of a report estimating total power usage for all servers in the US: a rate of around 5 gigawatts. One mid-range server draws around 450 watts, and infrastructure power usage is estimated as being equal. So if we say that the SDMB has one server (with infrastructure)
drawing a kilowatt, a hamster-powered generation plant operating at 50% efficiency would need to generate 2 kilowatts raw, and that would require 5000 hamsters working at maximum crusing speed. Allow time for breaks, replacements, sleep, etc, and I could easily see overlapping shifts of 5000 hamsters, or possibly 15 or 20 thousand hamsters.
Now, what if the power source were people on bicycles?
Back in the 80s, I had a go of an exercise bike that was rigged up to show output in watts. I could peak at 400w for short bursts, which apparently was enough to power a 1980s model television. I forget what the cruising output was, but I think it was a quarter to a third of that.
So maybe you’d need about ten average-fitness people to power this thing then. You’d need to relieve them after what… an hour? Say twenty people per eight hour shift, assuming breaks and absences, to give you your ten. Fifty or sixty pedallers over the 24 hours?
So about 100 watts? Great! I can power my lappy all by myself! The MacBook Pro power adaptor draws 85 watts.
I think that we have to figure in the energy required to feed and house the pedallers (or the hamsters, if we’re using them instead).
I seem to recall reading a paper a few years ago that looked at the absolute energy throughput and efficiency of an agricultural muscle-based economy (I believe the Roman Empire was the example). They went back several levels and looked at the energy required to harvest the feed needed for the oxen to harvest the grain needed to feed the armies that brought the food to feed the cities. I’ll see whether I can find it.
The MacBook Pro power adaptor draws 85 watts.