Combined network and storage development. Renewable integration efficiency assessment

In the framework of the European "Fit-for-55"package, targeting climate neutrality by 2050 and a 55% reduction in greenhouse gas emissions by 2030, the Transmission System Operator (TSO) has to guarantee increasing penetration of renewable variable generation while fulfilling high standards of security of supply, market efficiency and level of service. New approaches for cost-effective power system development strategies definition and flexibility requirements are needed, under the uncertainties related to the variability of renewable generation and load profiles evolution. This paper presents a novel approach for the long-term transmission planning, addressing the challenges issued by increasing renewable energy integration. The target capacity assessment methodology developed by the Italian TSO is firstly applied for the identification of optimal additional transmission capacity and storage system needs, deriving an integrated and cost-effective development strategy for a test power system in a very ambitious future scenario. Once the optimal case is obtained, market-based indexes are assessed to evaluate the level of renewable energy integration reached in each case under study.