efficiency of everything!

Hi followers,

today im going to write something totally different, so be pepared to read some crazy stuff ^^

Okay, yesterday i had a conversation with a friend of mine (yeah, i have friends.... weird). It was about the efficiency of different motor types because he is a auto mechanic.
Then whe have seen a piece of bun on the floor and i asked "ever wondered what the efficiency of a bun is?"
After that question we had a huge discussion what you have to research to find that out.
I couldnt resist so i have done some research:
effeciency = energy you can use from it / energy you put into something
Example:
A 60W light bulb has a efficiency of 5%. You put 60W of power in it and only 5% are formed into light. the rest is warmth.
I thought buns would be better but read this:

So a normal bun has around 1053 kJoule of energy for your body.
not much because a normal adult man needs 7100 kJ each day. That doesnt mean you should just eat 7 buns each day. But theoretically it would be enough.
Check.

Lets say we already have all incredience at home and wont calculate what energy there would be needed to make the incrediences. That would be to much.
Your body needs for 10min of making the pastry around 55kjoule.
While you just watch 20min of backing the buns your body needs around 58,8kjoule.
A normal oven uses 1500 - 2000 Watt each hour. We bake our bun for 20min so lets say we need 300W just for the oven.
Remember:
Until now, we just have the energy we need for our oven and our own energy.
We dont have the energy which is needed to create all the incrediences. But after 15min of googling i gave up.
300Watt/20min are 1,8MJ (this was also googled) ^^

efficiency = energy output / energy put
efficiency of a bun =  energy we get from the bun / energy you put in to create it
efficiency of a bun =  1053 kJ / (55KJ + 58,8KJ + 1,8MJ)
efficiency of a bun =  1053 KJ / 1.9138 MJ
efficiency of a bun =  0,0055%


Talking about diesel motors would be bad with an efficiency of 30%....
Buns are killing this world!

Bye ;D


Edit:
Made a mistake but corrected it with a mistake. 7000 buns a day? Nonsense! just 7. But i calculated wrong in the first place with the numbers but in the end the result was the same. Fighting mistakes with mistakes. Yeah!