Human power consumption
July 2009 (index)
What is the power consumption of the human body? No doubt there are various measurements that could be made using complex and expensive equipment, but we can make a reasonable estimate using simple maths.
Power is energy per time: Watts are Joules per second. So to work out power consumption it's helpful to know energy consumption. If you have some packaged food lying around it may well tell you the answer.
A handy packet of biscuits tells me that adult energy consumption is roughly 2,000 kcal per day.
Some biscuits
Helpful, but ideally I'd like to know this in Joules. I could try Google, but again the biscuits come to the rescue: I can convert between Joules and calories becuase the packet tells me that the energy of one biscuit in both units, so 292 kJ = 70 kcal.
That's roughly 4 kJ per kcal. So 2000 kcal per day is roughly 8,000 kJ or 8,000,000 Joules per day.
Next, how many seconds are there in a day? 60 in a minute, so 60x60 in an hour, and 60x60x24=86,400 in a day.
So human power consumption in Watts (Joules per second) is about 8,000,000 divided by 86,400 or about 100 Watts.
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