Hardly anyone doubts that we will have to make profound changes to our energy model, without waiting too long. Currently, most of the energy comes from fossil fuels, and its dependence is total in the transport sector: 95% of the energy comes from petroleum products. Fossil fuels are running out, however, but if they were not, we would have another inevitable reason to look for an alternative: the need to fight climate change.

However, the problem is not merely representative. One of the main features of fossil sources is the high energy density – which is declining, by the way; a barrel of oil today gives us less energy than one of 50 years ago; in a brief stretch of history we have had access to a great deal of energy. In this prosperity, Western society has built its current way of life and social organization itself. In this respect, the countries that are experiencing rapid development also want to go. But it won't be possible. The new energy model, in addition to using other sources, will require a reduction in consumption, as the enormous energy intensity of oil, coal, etc. cannot be obtained from these sources. It's not just about taking efficiency improvement measures, too, of course; we have to start to be aware that we're going to have to live with a lot less energy.