Impacts of Non-Programmable Renewable Sources Penetration on the Italian Energy System: A Tool for Scenario Analyses

The penetration of renewable sources in the national energy mix is necessary for most of the industrialised countries in order to comply with the ever-challenging constraints imposed by environmental impact reduction policies. However, a big family of renewable sources have the peculiarity of being non-programmable, that is very variable throughout hours and seasons. While the traditional electrical grid management philosophy has always been oriented towards the timely fulfilment of the demand via a set of conventional uninterruptible (or hardly so) large power plants complemented with a set of quickly adjustable smaller power plants, the integration of non-programmable renewable (NPR) power plants may represent a challenge. The planning of this kind of plants has to be accurately assessed as an over-installation may result in an overproduction of electricity that the existing electrical network cannot be able to transmit and the system to absorb. The paper presents a tool, inspired by previous NREL studies, to evaluate the effects of the penetration of NPR sources in the Italian energy mix. The study starts from the definition of the load profile of the country and it assesses the percentage of load that can be fulfilled by NPR sources until possible, taking into account the un-flexibilities of the electrical system, mainly due to the base load power plants that can hardly be adjusted. If more NPR electricity is instantly produced, this represents a waste (of energy and money). Thanks to the developed tool, a set of possible scenarios for the different geographical areas of Italy are presented and discussed, focusing in particular on the increase in the flexibility of the electrical system and in the penetration rate of NPRS.