The term 'energy transition' is used in every country slight differently. For example, Germany installs Renewables, the U.S. wants to be independent from foreign oil and developing countries want to have a well-working energy system with stable supplies. 

The article also has a short overview over energey transitions humanity has already seen. according to Smil (2010), the first was the taming of fire, the second was agriculture and the third was the utilisaion of fossil fuels. The fourth is then electrification (invention of devices, standardisation and the making of the grid). One could thus say we are amidst the fifth, which the authorof this article (Christian de Perthuis)  can't really describe as easily as the first four - he says it will free us of fossil fuels and result in a low-carbon industry.

Anyway, he rightly points out that transitions took a long time to take effect (at least several decades). I would add that maybe even the definition phase (of what is actually about to happen in the given socio-technological context) always took some time and obviously we are not done with that phase yet.

However, that is my takeaweay. The author closes with the following statement:

The elasticity of the concept of energy transition suits decision-makers nicely because it allows them to postpone choices regarding climate issues, though doing so makes future decisions all the more difficult. The history of energy systems, defined as complex assemblies articulating mixes of primary sources with the forces of transformation and types of use, teaches us that transitions take much longer and are more structuring than seems at first. Committing to them on the wrong basis risks paying much more in the long run.

http://www.energypolicyblog.com/2013/04/21/energy-transition-ambiguity-of-the-notion-of-variable-geometry/