A large number of various sized islands are spread throughout the south-east Mediterranean Sea. Most of these small islands face serious infrastructure problems, like the insufficient power supply and the low quality of electricity available at very high production cost. In an attempt to improve the life quality of all these isolated communities, an investigation concerning the financial viability of an integrated electrification solution based on one or more photovoltaic generators and an appropriate energy storage system is described. The main target of a similar solution is to maximize the contribution of the photovoltaic generator and minimize the life-cycle electricity generation cost of the remote island networks investigated. In addition, special emphasis is given in order to select the most cost-efficient energy storage configuration available. According to the results obtained for high and medium–high solar potential regions, the proposed configuration is found to be more cost-effective than the existing thermal power stations. Several side benefits like the improved electrical network reliability and the minimization of the environmental and macroeconomic impacts resulting from the replacement of the imported oil should also be considered.
The Greek territory includes a large number of islands of various sizes, spread throughout the Aegean and Ionian Archipelagos, Fig. 1. Although most large and medium-size islands present an acceptable status of life, this is not the case for the small and very small ones. In this context, due to the severe infrastructure problems and the imported oil-based electricity generation, the corresponding production cost is extremely high (Fig. 2). Additionally, the considerable increase of population during the summer season, owed to the visiting tourists, often leads to extensive electrical black outs due to the insufficient power supply [1]. On the other hand, the specific areas are favoured by a considerable RES potential [2], both wind and solar, that should not be neglected.
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Fig. 1.
Aegean–Ionian islands investigated and solar potential distribution of the Greek territory [2].
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Fig. 2.
Small Greek islands' peak load demand, APS annual energy production and electricity generation cost (€/MWh) [1].
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To confront the electrification problems and ameliorate the life quality of the specific areas [3], [4] and [5], the adoption of alternative electricity generation schemes, such as RES based energy storage configurations [6], [7], [8], [9] and [10], should be investigated. In this context, the aim of the present study is the financial evaluation of combining photovoltaic (PV) plants with energy storage systems (ESS) for the electrification of small, remote island electrical grids. Several small and tiny Greek islands with a population of less than 2000 and 500 habitants [11], respectively, comprise the target group of the specific research. Their hourly electricity consumption being less than 1 MWh and their peak load demand being inferior to 3 MW (see also Fig. 2) justify the decision to test the PV-ESS solution. Besides, one cannot neglect the support expected from the local habitants in favour of the RES based solution proposed [12] and [13].
Further, although the first installation cost of a combined PV-ESS configuration is relatively higher than the corresponding of an equivalent thermal power station, the high solar potential of the area and the extremely high production cost of the local APS already mentioned allow for the comparison of the two electricity generation schemes. In this context, by applying an appropriate sizing methodology, various representative PV-ESS configurations are dimensioned in order to minimize the operation of the local thermal power station (APS). Finally, since the optimum sizing of an ESS [14], [15] and [16] ensures higher system reliability and potential financial gains [17], by using different energy storage technologies [18] and [19] the designation of minimum life-cycle cost solutions [20] and [21] may be configured.
In the current paper, an integrated methodology is developed in order to determine optimum PV-ESS configurations for the electrification of small remote islands. The criteria for the adoption of the proposed solution encounter maximum energy contribution of the PV-ESS configuration and electricity generation cost lower than the respective of the local APS. In this context, the developed methodology is applied in small remote island typical cases. Both mature and more novel energy storage technologies are tested, while the influence of significant factors such as the solar irradiance levels and the local economy main parameters is evaluated.
From the results obtained, the electricity generation cost of the proposed solution is in most cases significantly lower than the marginal production cost of the existing autonomous power stations, even reaching 0.18 €/kWh, i.e. 42% less than the respective value for the APS operation. Significant change of results is caused by the variation of both the solar irradiance values and the local economy factors. Note, however, that only in few cases of maximum energy autonomy “do” and zero State subsidy “γ” did the electricity generation cost of the PV-ESS exceed the respective of the local APS.
Under the given circumstances, the proposed photovoltaic-energy storage configuration is thought to comprise a cost-effective energy scheme, able to solve the urgent electrification problem of the numerous small, remote islands. Apart from the financial gains expected, the increased reliability regarding the security of supply along with the minimization of atmospheric pollution and macroeconomic cost due to the imported oil, should also be considered.
