Lighthouse island 1: Unije
Location and general description:
The Cres-Lošinj archipelago is located in the Kvarner Gulf, in the Northern Adriatic Sea with a total surface of 503 km2. The average temperature in the islands ranges from 7,3 ºC in January to 23,8 ºC in July.
Regarding the distribution grid, Cres island included a meshed 10(20) kV grid counting with 2 35/10 kV and 1 35/20 kV substations, implying a total of 20 MVA, while Lošinj island includes three substations of 110/35 and 35/20 and 35/10 kV, respectively, with a total capacity of 64 MVA.
Both islands are connected to the mainland grid by a 110 kV submarine cable. Although Unije just count with 88 permament inhabitants, this number increases up to 200 during weekends and to more than 800 during holiday periods due tourism, specially in summer season. Finally, Unije counts with the Energy Self-Sufficient Island Plan.
Demand and consumption:
Total island of Unije: 1209.24 MWh
Generation capacities in the archipelago includes a 5 MW PV plant in the islands of Cres and 1 MW PV plant in Unije that will be completed and coupled with a BESS during INSULAE project, benefiting from previous investments made on the island.
The rest of the inhabited island do not have any generation capacity, but they are interconnected with the rest of the islands. Hence, an underwater cable is going from the Island of Losinj to Srakane and then to Susak and Unije which are bigger islands.
Regarding water supply, the lake of Vrana, located in the Cres island, is the main source of fresh water and it is transported by boat to Unije. In this sense, desalinization plant will be operated during INSULAE project to improve the water supply of the island and contribute to the energy system management.
The power of the small Islands relies on the power cable that connects them to Lošinj, being stability and energy quality one of the main problems of the islands. There are specific problems on the islands especially during summer days when the grid is overloaded and the stability of the network (n-1 criteria) is threatened.
Hence, innovative approaches in energy storage systems are very interesting in this particular case. Besides, as a consequence of the tourism, there is a water lack during vacation periods.
The lake of Vrana supplies the island of Unije with fresh water but the massive tourism is threatening the natural water supply of the lake. Thus synergies between water supply network and the grid will be tackled during INSULAE, while preserving the environmental resources and local ecosystems.
The islands from the Cres-Lošinj archipelago are a representative case of many islands from the Mediterranean Sea, in terms of similar climate conditions, relative scarcity of water, little interconnection with the mainland and heavily influenced by tourism seasonality.
Additionally, Unije can serve as a pilot island included in an Archipelago thus the solutions adopted in the island will be easy replicated and use in the rest of the Kvarner Archipelago as INSULAE projects counts with the municipality of the whole archipelago in the consortium.
Innovations addressed and solutions to be implemented:
Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb.
Ericsson Nikola Tesla d.d.
Institution Regional Energy Agency Kvarner.
Vodoopskrba and odvodnja Cres Lošinj (Water supply and drainage Cres Lošinj Ltd).