Water resources play a fundamental role in the national energy system, both directly in hydroelectric plants and indirectly in other components of the system that use water at one or more stages of the production cycle (cooling, biomass cultivation, carbon capture and sequestration – CCS). At the same time, water is crucial for civil, agricultural, public, and industrial uses, and this multiple use often leads to conflicts that must be resolved through priority management.

Although information on water availability and demand at the national level is still relatively scarce, the need for a comprehensive view of the qualitative and quantitative interactions between the water system and the energy system has gained increasing importance in recent years. This has led to a series of international studies on the so-called Water-Energy Nexus (WEN).

The overall objective of this line of research is to contribute to the improvement of energy system sustainability through a better understanding of the water-energy interaction. This study has developed a statistical model to evaluate hydroelectric power production based on national hydrological data and plant characteristics.

Interactions between water and energy in other areas, both for the national energy system and for civil and economic uses, have been addressed by developing a methodology that, starting from available data and identifying key parameters, allows for evaluation over several years.

In particular, an update of available data, thanks to recent publications, has led to a review of methodologies for estimating water flows for the industrial sector and for cooling thermoelectric plants.

The estimated data have been used to create a schematic representation, through a Sankey diagram, of water-energy flows at the national level, highlighting both the supply (water resources) and production/import phases (energy resources) as well as the consumption for various uses of resources.

The resulting diagram provides a snapshot of the situation for the years 2016-2018 but is intended to be continuously updated based on new data availability.