# Energy Transition on Sifnos: An Approach to Economic and Social Transition and Development
## 6 Uncertainties  
### The Interconnection of Sifnos with the Mainland Grid  
The Independent Power Transmission Operator (IPTO), namely the utility in charge for the mainland grid in Greece, has scheduled the Greek islands' interconnection with the mainland electrical grid [77]. This inevitably raises concerns with regard to the necessity for the construction of the hybrid power plant, as the insular grid will have been strengthened as a part of a considerably larger interconnected network. The obvious question is if the storage plant will still be required or, since the insular grid will be supported by the mainland one, if a single wind park will be enough for the compensation of the electricity demand on an annual basis. Firstly, although the necessity of the interconnection of Sifnos with the mainland grid is doubtless, on the other hand, it cannot guarantee the dynamic security and the energy supply safety, given the recorded failures and faults on islands interconnected with mainland grids or with neighboring insular grids. Interconnection cable faults in the Aran Islands, Ireland (5 August 2016) [78], in Menorca, the Balearic Islands, Spain (23 May 2015 and in October 2017) [79], in Tilos, Greece (17 January 2016) and in Kassos, Greece (25 July 2003) have led to total or partial loss for 1 day in Tilos, 3 days in Aran Islands and 6 days in Kassos. It is thus concluded that the only way to ensure a secure power supply in an insular system, regardless of whether it is interconnected or not, is the maintenance of guaranteed power production on the island.  
Guaranteed power production can be supplied either by keeping the thermal generators in stand-by operational mode, or with the installation of electricity storage plants. The first alternative requires that the operator uses the fixed electricity production unit (EUR 121.45/MWh on Sifnos) [8]. By accounting for the electricity production cost in the mainland grid (EUR 58.099/MWh in summer 2021 [9]) and the transportation losses, the total electricity production cost on Sifnos will be configured higher than EUR 200/MWh. Consequently, in this way, firstly the anticipated drop in the electricity production cost is not achieved, at least to expected extent, while, secondly, the electricity production on the  
Figure 19: The overall energy transition plan on Sifnos with the opening developmental perspectives.  
island will still be dependent on imported fossil fuels, and hence the major objective of the energy transition objective for energy independence is not fulfilled.  
At the same time, the necessity of the introduction of electricity storage plants even in the Greek mainland grid has been assessed by the Greek Ministry of Energy and Environment as an essential step for the secure integration of the continuously increasing installation of RES projects. The Ministry has announced the forthcoming administrative and licensing process for the installation of single electricity storage plants, namely not necessarily as a component of a hybrid power plant. The enactment of the development process for electricity storage plants, together with a relevant framework which will ensure their economic viability through the assessment of a sensible and justified electricity selling policy, will guarantee the technical feasibility and the economic viability of the hybrid power plant on Sifnos, even in the case of a potential future interconnection of this insular community with the mainland grid.