Almost all of production in a modern economy comes from machines. Machines have been utilized to augment both manual and intellectual capacity. Machines require energy. Therefore our economy runs on energy.

Think about it. Why do most people have jobs sitting on their asses typing on a computer instead of searching for food and doing other obvious things related to survival? Because machines are doing the work for us! Because Energy!

Let's be real, it's really hard to find an occupation that doesn't involve an energy consuming machine.

Take for example: Food. Factory farms, tractors, pesticides all guzzle gasoline like crazy. People assume that if gasoline disappears, you can just start biking to work. The reality is, if gasoline disappears, people will begin to starve.

Another example: Big Data and IT. What do you think those servers are running on? Hopes and dreams or Energy? Take your pick.

The cities of america are constructed in ways so that the laborer must get in a car and consume a bunch of energy just to get his ass to the location where he actually does work... Our entire infrastructure is built around energy. It goes further then that, our urban infrastructure is built on the assumption that energy is limitless; suburban infrastructure relies on gasoline, once that's gone, so is suburbia.

Modern civilization and energy are intrinsically linked. The same way green house gasses and global warming are linked. There is no controversy. Period.

In short economic growth is Bounded by an upper limit and that upper limit is indeed energy.