Beehive energy budget

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Monthly Hive Energy Budget

I used the data from Dave Cushmans site for population, number of foragers, number of drones and from this worked out the cost of heating the hive, feeding the inhabinents, cost of flights and the egg laying pattern on a monthly basis.

This gives me the energy coming into the hive and the energy expended by the hive. Then starting in November with 15 kg of honey stores and see where we get to by the end of 12 months.
 
Very interesting topic, but truth is ... If it wasn't raining outside I would be working with the bees on the longest day instead of at a computer screen.

Ah for those hazy days of summer we used to have, or was that on the TV?
 
:iagree:2ins of rain last night and a temp. of 12c at 13:21...
Very interesting topic, but truth is ... If it wasn't raining outside I would be working with the bees on the longest day instead of at a computer screen.

Ah for those hazy days of summer we used to have, or was that on the TV?
 
I just love the fact we have members who will do this because I find it all fascinating. Thanks to one and all. As has been said, there are so many variables - but getting your head around averages and scale of things is great.
 
collected energy

1 foraging bee collects 500J of energy as 30mg of nectar in one flight
1foraging bee makes 3-10flights per day over a period of 10-20 days
a colony has 100,000-200,000 foragers per year
they make 15 million flights 12 for collecting nectar 2 million for pollen 1 million for propalis and water and 1.5 million by drones
a colony collects 600 kg nectar which converts to 300 kg honey
plus 30 kg pollen (15 mg per flight) and 20kg propalis
1kg honey converts to 12 million J
colony collects total energy of 3,600 MJ
 
Expended energy
population
queen lays 200,000 eggs in a year
population is 50,000 in summer and 20,000 in winter
total number of foragers is 150,000 with a typical life of 12 week
population turns over four times a year
drones have population of 10,000 for 6 months of the year. Eat 38MJ. So total cost 40MJ (3kg honey)
drones live for 90 days sexually mature after 38 days so fly for 50 days at 3 flights per day so make 1.5 million flights which costs 15 MJ
foragers
1flight collects 500J but costs 10J
15 million flights cost 150 MJ (12.5 kg honey )

heater bees

total energy expended 3,600 MJ
summer 2,000 MJ (166 kg honey )
winter 2 MJ (0.5 kg honey )
total other tasks summer 1,000 MJ (80kg) winter under 50MJ



other activities

new comb built by swarm 100,000 cells using 1200g of wax uses 90 MJ (7.5 kg honey )
royal jelly
water
eating



winter stores 15 kg honey or 180 MJ
 
Here is the data:
First the basic data collected from Dave Cushman's site. This for a Varrora free colony and as a coparison shows the population after a swarm. Then it shows the various cohorts of bees during any one month, drones, foragers, house bees, etc.

From this data you can take a stab at estimating the amount the colony eats, (population plus brood), how much energy is expended in flying and how much in heating the hive. The assumption in the latter case is that the more brood you have the higher the energy bill. Population is expressed as individual number of bees and the heating, etaing and flying costs as MJ.

View attachment 6770
 
Beehive energy budget

Using the above data you get the following results expressed as energy into the hive, energy expended, the balance (or difference between those two numbers for the month) and finally the overall energy position of the hive. I have assumed that the hive starts in November with 15kg of honey stores.

View attachment 6772
 
Of course this is a simple model and there are many assumptions and there is more work to be done on it to make it a better balance by the end of the year. There are further costs to the colony associated with the brood which I have not allowed for and would increase the energy expenditure. These need to be added in.

The next step is to see the effect of a swarm on the energy budget, or of bad weather in a particular month or of a high varrora count.

For me there were a number of surprising things that came out of the exercise.

1) The very large amount of energy the hive generates during the course of the year which is equivalent to 900 KWh or the energy to keep a lightbulb lit for 15 hours.

2) The very small cost of running the hive over the winter. The real cost to the colony is once the queen starts laying. The small winter population of bees is under real stress as it has a small number of foragers (even if the weather is good they cannot collect much energy) and a limited number of heater bees to heat a rapidly expanding brood. This is really where the stores come in which is 'funding' this expansion.
 
Good as ball park guesses? Not looked at others, but one obvious example stood out clearly.

Assuming bees in hive are end of month values, I had difficulty in reconciling 19 500 eggs laid in Feb/March, yet the colony expands by 27 000 by the end of April. Assuming 10 000 eggs laid in aerly April produced bees in April (an over-estimate, and the rest would be still as brood). That means that just 1 500 bees have expired in those two months. The attrition rates quoted for earlier in the year would indicate this is not quite right?

So a bit simplistic (should be a split table for the swarmed colony as the subsequent values are for an un-swarmed colony) but it shows the trends.

Some of the totals, I noticed, are fairly inappropriate and/or awry.

So beware in drawing definitive conclusions from the data. Trends are OK.
 
equivalent to 900 KWh or the energy to keep a lightbulb lit for 15 hours.

A few zeros missing here?
 
I didn't realise that the drones acted as heater bees, thought they were completely ornamental apart from their main task!
 
I didn't realise that the drones acted as heater bees, thought they were completely ornamental apart from their main task!

You are right. They produce heat but hey are not heater bees.
Why bees kill drones when night temps turn too cold ....??? Why their kill their hearth?
 
Good as ball park guesses? Not looked at others, but one obvious example stood out clearly.

So a bit simplistic (should be a split table for the swarmed colony as the subsequent values are for an un-swarmed colony) but it shows the trends.

Some of the totals, I noticed, are fairly inappropriate and/or awry.

Quite right, this is a work in progress and I want people to comment and add further data, build on this.

The totals are end of month totals and taken from spider graphs so that are not full reflections of the course taken day by day, so naturally the totals do not add up. For instance Mays population starts at 35k and ends up at 52k which is quite a steep growth curve and not at all reflected in simple start and end totals. Likewise the data is from a variety of dates ranging from 1984 up to 2011 and a range of hives in different parts of the country, different hives, etc.

Likewise I have not managed to account for all the expenditure so that you end up with far too much honey at the end of the year.

But if you have more accurate date then lets have it.
My data source was this page:
http://www.dave-cushman.net/bee/populationdynamics.html
 
I didn't realise that the drones acted as heater bees, thought they were completely ornamental apart from their main task!

What drones do is a bit of a mystery but there is some evidence that they contribute to the heating of the brood since they are large and have powerful flight muscles but they are not heater bees as such. Heater bees drop down into empty cells within the brood area and heat themselves and the surrounding comb till exhaustion and they stagger off to a nearby nectar cell.bee-smillie
 
The extra food the fat bees eat :drool5:
Are you all accountants or maths teachers here, here's my angle on it, bees collect nectar turn it into honey I collect the honey happy days :sifone:
 

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