A thermodynamical critique of efficiency

Apparently, in economics efficiency is evaluated by comparing actual output to potential output. If you want to increase efficiency, increase production, regardless of costs! To me this sounds like the runaway train scene in The Marx Brothers' Go West. In Samuelson's first chapter on macroeconomics, he relates efficiency and whether or not the economy is within its PPF to the ratio of GDP to potential GDP, clearly conflating productivity with efficiency.

In thermodynamics, efficiency is the ratio of work done to energy spent or, in economic terms, the ratio of production to resource use. The amount of work done per unit time is called power.
To make an analogy, it seems that if a new fridge cools ten times as much as an old one at 100 times the energy cost, it might be called "more efficient" by an economist. A physicist would call it "more powerful" but "less efficient".
If standard economic analysis of the energy market confuses productivity with efficiency in this way, it's no wonder we're running out of fossil fuels as quickly as we are.