Apr 14 2010
Net Energy vs Efficiency
Hello again–
Between all of the supplements, the math, and the study guide, I’m having trouble figuring out the differences between net energy and efficiency. Because net energy is the amount of usable energy, that is, total energy minus energy needed to create that energy, while efficiency is input equals output divided by percent efficient, which to me sounds like two different ways of saying the same thing.
Maybe it is just the way that I am reading it and need a real life example to clear it up, but either way, I would appreciate any way to simplify this for me.
I can see how they would seem pretty similar, but I think the key difference between the two is net energy is how “efficient” harvesting the energy (mining it from natural resources etc) where efficiency is how much of the harvested energy is actually being used for what we want it to be used vs how much is given off as heat.
In net energy, we are putting in energy to get back energy, in a light bulb, we are putting in energy to get back energy(lumens?). That is, unless you just use your wand for some Lumos action, right Syd?!
So I guess in principle, they are the same thing, just where they are applied in the material flow economy is different. Net energy is the furthest upstream, while efficiency is the furthest downstream.
ehh..sorta, RG. Net energy has more to do with energy put into getting the fuel versus energy obtained when it is burned. If it takes 3 times more energy to extract and refine oil sands compared to barrel of light crude, then why would we want it? Efficiency is HOW WELL a device does its job (or a person). So if a light bulb is supposed to make light, but it only converts 5% of the electricity input into light then it is not very efficient is it?