Fossil energy: From conventional oil and gas to the shale revolution

The fossil fuels have provided more than 80% of the total energy consumption for more than 100 years; although in perspective renewables are expected to be the fastest growing energy sources, it is likely that fossil fuels will dominate energy use at least through 2050. This is still due to the increased worldwide need for energy, to their superior energy intensity and reliability and to the very huge numbers that underline world exposition to fossil fuels, not easily substitutable. A few brief considerations, regarding the chain of production, transport and use of the energy carriers, make us realize that the success that oil has had as an energy source cannot be attributed only to its great availability and the relatively cheap price but also to the ease with which liquid hydrocarbon derivatives can be transported, stored and distributed for their final use. In fact, their liquid state enables their energy density per unit of volume to be optimized, and this has great advantages especially for the storage and the distribution of the carrier. This does not mean that there are not challenges and dilemmas in the exploitation of conventional reserves, such as for example the decline of great reservoirs for lacking of suitable technology and reservoir management, the increased produced water from oil reservoirs and related management and the need to cope with the issue of climate change due to the CO2 emissions. Attention will then be paid towards unconventional resources, especially those that have lead to the “shale” revolution: the deployment of huge reserves of shale oil and gas have deeply modified the overall energy picture in the last ten years, especially in the United States. By moving towards 2040–2050, oil and gas will remain crucial energy components, maybe with some less crude-oil production but more natural gas and higher use of electricity, produced both by gas and by renewables and also pushed by the advent of electric vehicles