[akshatrathi]

I wrote the story. The efficiency here isn't breaking the first law of thermodynamics. It's just the industry's way of measuring how much work gets done for a certain amount of input. If the work is heating or cooling, then shifting heat from in one direction or another can be done using heat pumps, which move three units of thermal energy for every unit of electrical energy consumed. Might that explain the conundrum?

[dudus]

But then aren't you comparing apples and oranges when you call both that and the loss as heat and noise from coal as "efficiency"?

[renewiltord]

Well, we're not interested in a thermodynamic comparison. We're interested in a useful-energy-obtained for useful-energy-spent comparison. For instance, if I leave a block in the sun and then bring it inside, I have only expended the energy to move the block out and then move the block in. It doesn't make sense for me to include the sun's contribution to the system because that's not a cost I incur.

The actual apples to apples comparison in efficiency _is_ the heat emitted by the block in my house divided by the cost of moving the block.

[foldingmoney]

This is a property of _what the device is doing_ (moving heat from one place to another) as opposed to being a property of how it's powered, though.