1.25 Million?

[swestrup]

I was just struck by an idle thought: if we wanted to power a person electrically, what would it take? The reason I ask this is that one major problem facing the builders of ultra-micro robotics (fly-sized spycams, smart dust, etc) is how to power it. I wondered if nature was so much more efficient in power usage, or if it was because we have a denser power supply in food than that available in batteries.

A quick check on the Net shows that 1 'D' Cell battery holds about 1200 mAh (milliamp-hours) or 1.6 Calories. Now, thats a physics Calories, which equates to 0.0016 food Calories. Per entire D-Cell. Now someone of my rough size and weight needs about 2000 food calories per day for maintenance. That works out to a whopping 1.25 MILLION D-Cells per day. Pricey!

If we do the calculation the other way we see that the 1.5 million amp-hours of energy I need in a day works out to about 96.9 watts of continuous power consuption, or about one decent light-bulb's worth.

So, I don't actually need all that much power, its just that current battery technology sucks big ones when compared to something like food energy, and THAT's why we need fuel cells.

Now that I've worked that all out, I should be able to sleep.

Comments

[foi-nefaste.livejournal.com]

... And posts like this is why I love having geeks on my f-list. Interesting!

[joenotcharles.livejournal.com]

Man, when you put it that way, the "human battery" nonsense in The Matrix makes a lot more sense.

[swestrup]

Except that humans are net power consumers, and a diesel generator is a better source of power.

[sps.livejournal.com]

? If you want to generate 100W of waste heat, a lightbulb takes less space. Or if you're hell bent on organic waste heat, use pigs, they have 20 times the power density we do. I tihnk any effort expended in putting "The Matrix" and "makes sense" together in a sentence is wasted ;).