Dear Adrian,
The "calorie" used by the food science folks is the so called "large calorie"
whereas, the calorie you show below is the small calorie used by chemists.
Those 200 calories listed on the beer can are actually 200 kcal. This is why
after peddling the machine at the gym as fast as I can for about half an hour I
look up at the display and see that my score is only a disappointing 1 beer. If
(oh, if only ...) what you wrote were true, I could burn off that can of beer on
the way back up the stairs from the refrigerator.
One the good side, yes, you can power a fuel cell off someone's blood supply.
(It would be great if you had a selective membrane that only passed "bad"
cholesterol to the converter.) Also, I have given some thought to a system that
uses low pH stomach acid against high pH intestine secretions to run half
cells. This is much easier than having to break down big organic molecules.
However, if you want electricity from food it is hard to beat the basic sodium
pump used in neurons. Ask any electric eel or fish about this one.
-Ken
Adrian Tymes wrote:
>
> > How many kilowatt hours per beer? (or vice versa)....
>
> It depends on the total calories (cal. per beer * number of beers):
> 1 calorie = 4.186 joules
> 1 joule = 1 watt second
> 1 watt second = 1/(1000 * 3600) kilowatt hours
> So, 1 calorie = 4.186/36000000 kilowatt hours =~ 1.163 * 10^-6 kWh
> Assuming about 200 calories per beer, that's 4000-5000 beers per kWh.
> Of course, this is also assuming 100% efficient conversion; double the
> beers if only 50% of the energy can be converted to electricity with
> the rest lost to heat.
>
This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:56:22 MDT