The particularly challenging objective of eliminating the net balance of anthropogenic climate-altering gas emissions to address the current climate crisis cannot be achieved until a few decades from now, as it requires radically shifting energy production from fossil to renewable sources.

The scientific community agrees that, in the meantime, the replacement of fossil fuels with synthetic fuels that have a lower impact on climate-altering gases, could facilitate the aforementioned transition.

For example, through electrolysis, and therefore consuming electricity, hydrogen can be produced which can be used directly as an energy carrier for end uses, e.g. in industry, or it can be produced through appropriate chemical processes and used for producing synthetic fuels, with a lower climate-altering emission balance. Water electrolysis technologies are flexible and therefore also offer the electricity system other advantages, e.g., they can be used to absorb part of the overgeneration resulting from massive penetration of renewable generation from non-programmable sources, and they can also provide the system regulation services. These types of systems are categorised as ‘Power-to-X’.

The simulation tools used to carry out studies on the development scenarios of Energy Systems in the coming decades must be able to consider these types of systems appropriately. Therefore, we added a new functionality of Power-to-X plant simulation to the sMTSIM medium-term electricity system simulator which RSE has been using since years in its scenario analysis of the Italian and European electricity systems.

This work therefore presents the mathematical formulation of the new functionality that has been added to the sMTSIM simulator, i.e., the possibility of modelling consumption units that use electricity for producing a synthesis gas (hydrogen, methane or other) which can be used directly to immediately satisfy a given requirement or be stored to satisfy said requirement at a later time. A test case based on a scenario of the Italian Electricity System at 2050 is also proposed.