Cybernetics and power

For a while I’ve wondered how to efficiently and unobtrusively power cybernetic implants. To me, the idea of having to replace batteries and recharge things that are part of my body is antithetical to the whole idea of implants. Implants should blend with organics and utilise the natural power sources within the body.

So, how much wattage does the human body produce naturally? Well, this is what the Basal Metabolic Rate (BMR) indicates, or more accurately, it indicates the average amount of energy expended on day-to-day activities… if you had a particularly active day then this would jump up higher.

There’s a BMR calculator here and according to it, my BMR is 1906 kcal/day. This works out to about 92 Watts… not much more than a light-bulb*!

In order to tap into this energy source, we need to adopt one of the energy currencies of the body. Some ideas might be glucose, ATP, or the electron transport chain (although the latter two are generally intracellular processes, so I’m guessing it’d be harder and potentially more dangerous to try these). Further, there should probably be some regulation of utilising the body’s energy, so that if these energy substrates drop too low in concentration then the implants should either switch off and warn their user that blood glucose levels are low.

As a result of this, it’ll give you an excuse to eat more delicious food to power your implants. Or, if you’re trying to lose weight, you could run the main processor overnight to encode your previous day’s memories to xvid – or regularly present the vocabularies of 5 foreign languages to your brain as you dream – hablo castiano un pocho 😉 )

But then, a negative consequence of having more implants is exactly this – your body will have to work harder to sustain them. Depending on the strength you place on metabolic rate affecting longevity, more implants could then start reversing the gradual increase in lifespan we’ve been seeing during the last couple of centuries. Of course, they’ll be plenty of others trying to come up with engineered ways to halt or reverse this metabolic aging.

Anyhow, I hope the cyberneticists are taking this all into account, because it first gives designers an idea of the wattage they have to play with and also because I’d really prefer to avoid having to plug myself in at night!

* 1906 * 4.18 kJ/kcal * 1 day / 8.64e4 sec = 92.2 Watts. And upon conducting research about this, NASA and HP labs have made the comment in the past that the human body produces about the same amount of energy as a 100 Watt light-bulb needs.


#1   Cass on 06.08.09 at 5:59 pm

In my research on electric bikes, I found that the human body apparently can put out about 100 watts per hour when cycling at full tilt: a whole heap more above BMR, so if you’re cycling a lot you’ll need to eat quite a bit more. Of course, it’s way more efficient to get the motive power for an electric bike from more direct sources (preferably renewable power) than eating more to cycle, so I’d say with any cybernetic components it would probably be more efficient to find a more direct power source than metabolic energy. How about nanotube solar cell hair extensions? 😀

#2   Joel on 06.08.09 at 7:34 pm

Hehe, I reckon you should look into that, then you’ll be ready to jump on the demand and become a market leader in personal (and fashionable) power sources!

#3   Linas on 08.30.09 at 2:01 pm

When its cold outside, and cold inside, and your bundled up in a blanket … that 100 watts explains a lot about why it seems to take forever to get warm. Its also why swimming in cold water can really drop your core temp — there’s just not enough power to keep you warm.

#4   Joel on 08.31.09 at 10:16 am

@Linas Yeah – that’d be the case when it’s really cold, but note that the 100W figure is just a basal metabolic rate when you’re body is at rest. If it’s trying to keep itself warm, it’d probably use more… (which is one reason why people get hungrier in winter, besides the instinctual desire to add a layer of insulating fat).

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