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Author Topic: Measuring Bee Energy in Watts  (Read 1225 times)

Offline BlueBee

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Measuring Bee Energy in Watts
« on: April 01, 2011, 07:00:47 PM »
More entertainment for y’all.   Have you ever wondered how much power your bees are generating?  Is it 1 watt?  10 watts?  100 watts?  1kw?  1.21 GigaWatts?  Can we use bees to make a flux capacitor?  There are easy ways to figure this out and there are hard ways to figure this out.   

The hard way to figure this out is to use Newton’s laws of heat transfer and integrate over the surface area of a hive using calculus as I suggested in a previous post.  That requires a lot of data and expensive equipment to compute.  To be as accurate as some want, you would need to measure the temps at every point on the surface.  That would require either a IR camera or a boat load of thermisters. 

However there is a much easier way to find out how much power your bees are making if that is your goal.  The easier way requires very little math, less sensors, is pretty low cost, and measures the amount of energy your bees are generating IN WATTS by using an equivalence principle.

The method is to set up two identical hives in the same location; I’ll call them hive #1 and hive #2 here.  Hive# 1 will have your bees in it, while hive #2 will be void of all bees.   Next add some temperature probes in each hive at the same locations.  Put some thought into where to put them (ie NOT in the cluster, NOT near the cluster).  Finally add 4 of my bee heater blocks into the bee-less hive #2 in the same area where the bees are located in hive #1.  Don’t turn on the bee heaters yet.

Start measuring the temperatures in each hive.  Since the bees will be making heat in hive #1, hive #1 will be warmer than hive #2 since the bee heaters in hive #2 are turned off at this point.  (Needless to say, this whole experiment will work much better with foam hives, but that is a different story)  Now start ramping in electrical power to my bee heaters in hive #2.  Keep ramping in power until your steady state temperature readings in hive #1 = hive #2.  At that point, the electrical heat going into hive #2 equals the bee heat energy going into hive #1. 

This is the point of thermal equivalence between the two systems.  When both hives are measuring the same temps in a steady state, then the heat sources within the hives must be putting out the same amount of energy (First Law of Thermodynamics).  Hence if we know the electrical heat flowing into hive #2, by equivalence we know the amount of heat the bees are generating in hive #1.

Computing electrical energy going into hive #2 (as heat) is easy.  Electrical power going into a resistive load is P = VI.  Where V is the voltage drop over the bee heaters and I is the current flowing through the bee heaters.  When V is in volts and I is in amps, the power is in watts.

When both hives are thermally equal, the electrical watts going into hive 2 = the number of watts the bees are generating in hive 1.

Offline deknow

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Re: Measuring Bee Energy in Watts
« Reply #1 on: April 01, 2011, 11:26:29 PM »
...although I don't know upon what he bases his numbers, Jurgen Tautz has some interesting bee-energy numbers in "The Buzz About Bees"