Italy's "Energy Efficiency" plotted as a ratio of the GDP (constant dollars) to the energy consumption (data from the World Bank)
There is an old story in Italy (but also in other Mediterranean regions) that tells of a man who tried to train his donkey to work without food. So, he gradually reduced the beast's daily ration of hay. Later on, the man reported that, unfortunately, the donkey had died just when it had learned to go without any food at all.
The man of the story must have been an economist. He was trying to optimize the system and he had defined the "efficiency" of the donkey as the ratio of the work performed divided by the amount of hay consumed. He had found that reducing the amount of hay improved efficiency and, with impeccable logic, had brought the idea to its natural conclusion.
Something similar seems to be taking place with the economy of whole countries. Economists define as "efficiency" the ratio of the GDP produced per unit of energy consumed. Noting that this ratio has been increasing for many Western economies during the past decades, they conclude that economies are becoming more and more efficient. They even speak of "decoupling", noting that the GDP can keep increasing while the energy consumption remains constant - or decreases. This is supposed to be a wonderful thing.
Unfortunately, the problems with this optimistic interpretation appear stark clear with the case of Italy. Notice, in the graph above, how this "efficiency" shot up just when the Italian economy started to collapse, with a decline in GDP, loss of more than 25% of the Italian industrial production, massive increase in unemployment and all the related disasters. (See here, and here for reports about the post-peak Italian economy)
The increase in efficiency shown by the graph is a pure illusion. The Italian economy is not becoming more efficient but, simply, contracting. Industries are closing down and people become unemployed. As a consequence, less energy is consumed in manufacturing and for transportation. At the same time, other elements of the economic system, say, rents or property taxes, remain relatively unaffected; government spending, for instance, tends to go up. Hence, the GDP doesn't decrease as fast as energy consumption and the ratio of the two increases (*). Obviously, that's nothing to be happy about.
Concepts such as "efficiency" and "decoupling" seem to be based on highly aggregated parameters; too much to provide a useful interpretation of what's happening in a country's economy. That doesn't mean that the economy cannot get more efficient with time, just as a donkey may learn to work even with a reduced hay reaction. But, without energy, and especially without cheap and abundant energy, an economy simply starves and, eventually, it suffers the fate of the donkey of the story.
(*) The increase in the GDP/energy consumption ratio can be simulated by a dynamic model and it can be shown that it is just an effect of the time lag in the process of transformation of natural resources into capital. But that will take another post to explain.