Int. J. Global Energy Issues, Vol. 23, No. 1, 2005 43

The energy system

Christopher Koroneos*, George Roumbas and Nicolas Moussiopoulos Heat Transfer and Environmental Engineering Laboratory, Department of Mechanical Engineering, Aristotle University of Thessaloniki, PO Box 483, Thessaloniki, GR-54006, Fax: +302310996012 E-mail: [email protected] E-mail: [email protected] E-mail: [email protected] *Corresponding author

Abstract: The economic growth of the Dodecanese islands in Greece has been based solely on tourism and the electricity production is very critical in sustaining this economic growth. The electricity production is solely done with the use of diesel and heavy fuel oil. Even though there have been some efforts in introducing renewable energy of various forms, the results remain dismal. Due to this situation, it becomes necessary that the growth of energy demand must be given primary consideration. In the present work the energy system of Dodecanese islands is divided in the seven economic sectors in order to be evaluated.

Keywords: electricity production; demand projection; Greece; Dodecanese.

Reference to this paper should be made as follows: Koroneos, C., Roumbas, G. and Moussiopoulos, N. (2005) ‘The Dodecanese energy system’, Int. J. Global Energy Issues, Vol. 23, No. 1, pp.43–70.

Biographical notes: Christopher Koroneos is an Associate Professor at the Department of Management of Energy Resources at the Aristotle University of Thessaloniki and special Scientist at the Laboratory of Heat Transfer and Environmental Engineering of the Aristotle University of Thessaloniki in Greece. He was previously teaching at Columbia University in New York, where he also received his BS, MS and PhD in Chemical Engineering.

George D. Roumbas is a graduate from the Department of Chemical Engineering from 1992 to 1997 of Polytechnic School of the Aristotle University of Thessaloniki (AUT). His research interests are in the areas of fluid mechanics, liquid and solid waste treatment, environmental engineering, energy engineering and life cycle analysis. At the present time he is a research assistant at the Laboratory of Heat Transfer and Environmental Engineering Department of AUT, in Greece. He has been involved in several EU projects (FP5 and ALTENER programmes).

Nicolas Moussiopoulos is a Full Professor at the Aristotle University of Thessaloniki and the Director of the Laboratory of Heat Transfer and Environmental Engineering. He is also an Honorary Professor at the School of Mechanical Engineering of the Universitaet Karlsruhe. His research work deals primarily with the development of atmospheric wind and dispersion/chemistry models. He coordinated several large international research projects and is the author of more than 300 scientific publications, among them more than 80 in

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44 C. Koroneos, G. Roumbas and N. Moussiopoulos

peer-reviewed journals. Professor Moussiopoulos is a member of the German Academy of Natural Scientists Leopoldina and in 2002 he was awarded the Order of Merit of the Federal Republic of Germany.

1 Introduction

The prefecture of Dodecanese, with as capital city, is on the south-eastern part of Greece and it comprises 200 islands of which 19 are inhabited. The total population of the islands was 1,64,000 based on the national census of 1991 this figure has increased by 16.3% based on the national census held in 2001 reaching at 1,90,071 inhabitants. All the islands have a lot of common features but they differ a lot in terms of size, morphological characteristics and population. The prefecture of Dodecanese has the 1.7% of the total population of Greece with the second highest natural population growth rate in the country: 4.1 births/1000 inhabitants. The contribution to the national gross domestic product GDP is 2.1% (seventh greatest contribution) from which 89% comes from services sector (35% from hotel and restaurant services). The GDP per capita is 14,086 EURO which is the fourth in the country and 118% of the average GDP per capita in Greece. The area of Dodecanese is 2,600 km2 with Rhodes covering 54.2% of the total. The three biggest islands, Rhodes, , , cover about three-fourths of the total area of Dodecanese (Figure 1). This indicates the difficulty in providing services to all the small-scattered communities.

Figure 1 Map of Dodecanese

The Dodecanese energy system 45

The energy syste m of Dodecanese islands uses fuel oil, diesel and petrol for the production of electricity and the transportation and agricultural sectors. The islands have various electricity grids that allow to satisfy electricity needs in a more optimal manner. In order to examine the energy flow in the Dodecanese islands the energy consumption is divided into the following sectors (Figure 2): • Residential sector includes all the domestic activities that consume energy such as lighting, cooking, air conditioning, space heating, water heating, and other electric uses. This sector contributes 17.9% to the total annual energy consumption. • Commercial sector includes the energy consuming activities (lighting space heating, air conditioning) that refer to commercial activities (food stores, entertainment, etc.). This sector represents the 6.3% of the annual energy consumption. • Hotels sector is examined separately from the commercial sector because the energy consumption in this sector occurs in the summer period due to tourism. It contributes 9.4% to the annual consumption. • Public sector includes public buildings, schools, street lighting, etc., and constitutes the 2.9% of annual consumption. • Transport sector includes vehicles for private use and buses. It has the major contribution in the total annual energy consumption (56.9%). • Agricultural sector is mainly made up of greenhouses and has the small contribution of 1.8%. • Industry refers to industrial activities and has a small contribution of 5%. The primary energy input consists mainly of fossil fuels (95.5%) while renewable sources contribute only a small percent (4.5%). The fossil fuels used are gasoline, diesel, heavy fuel oil and light petroleum gas (Figures 2 and 3): • Gasoline is used as fuel in transportation vehicles and makes up the 20.9% of the total primary energy input and 21.9% of the total fossil fuels consumption. • Diesel represents 35.3% of the total fossil fuels consumption and 33.7% of the total primary energy. The primary use is for electricity generation (40.3%) and as fuel for vehicles (46%). The rest is used for space and water heating in residential, commercial, hotels and public sectors and for heating in industrial and agricultural sectors. • Heavy fuel oil (HFO) has the largest contribution in the primary energy input (40.1%) and represents 41.9% of the total fossil fuel consumption. It is mainly used for electricity generation (95%) and only a small percent is used in industrial and agricultural sectors for heating. • Light petroleum gas (LPG) contributes only a small percent (0.9%) to the primary energy input and is used in residential sector for cooking. Renewable energy sources are used in the residential sector for domestic activities. Biomass is used for cooking, space heating and water heating while solar power is used only for water heating. In hotels sector there is a large contribution of solar power in water heating.

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Figure 2 Overview of energy balance in Dodecanese islands (values 1992)

Figure 3 Distribution of total primary energy input in Dodecanese islands (1992)

The Dodecanese energy system 47

Electricity represents the 24.5% of the total energy demand in the islands (Figure 4). It must be mentioned that this electricity figure includes diesel and HFO that have been used as production fuels.

Figure 4 Energy input after power generation

Due to the fact that residential, commercial, hotels and public sectors have common characteristics (energy is consumed in cooking, water heating, space heating, air conditioning, lighting and other electric uses) they will be examined together. On the other hand electricity generation and consumption will be examined separately.

2 Residential, commercial, hotels, and public sector

Residential, commercial, hotels, and public sectors represent the 36.3% of the total energy demand in Dodecanese islands (Figure 2). The residential sector comes second in energy consumption (17.9% of the total energy demand) after the transportation sector. The energy consumption in these sectors is due to activities such as cooking, water heating, space heating, air conditioning, lighting and other electric uses. Lighting and various electric uses (29.1%), water heating (28.6%), and space heating (28.6%) contribute the most in the total energy consumption for these sectors (Figure 5). The distribution of energy consumption for each of the above sectors varies for the different activities (Figure 6): • in residential sector space heating has the major contribution in energy consumption (47.8%), followed by lighting and various electric uses (24.3%), cooking (14.3%), and water heating (11.7%). • in commercial sector the most energy is consumed in lighting and various electric uses (49.8%) and air conditioning (46.5%). • in hotels sector water heating contribute the most in energy consumption (88.6%). • in public sector the major energy consuming activity is lighting (79.8%).

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Figure 5 Distribution of energy consumption residential, commercial, hotels, and public sectors

Figure 6 Energy consumption distribution for each sector

The energy supply for these sectors is provided mainly by electric power (62.7%) followed by diesel (14.5%), which is used for space heating mainly, and for water heating. Biomass (11%) is used for cooking and space heating while solar power (7.9%) is mainly used for water heating (Figure 7).

The Dodecanese energy system 49

Figure 7 Distribution of energy supply

Electricity is mainly consumed in lighting and various electric uses (46.5% of the total electricity consumption in these sectors), water heating (27.2%), and air conditioning (14.9%) (Figure 8).

Figure 8 Electricity consumption distribution in residential, commercial, hotels, and public sectors

Air conditioning, lighting and other electric uses consume electric power while cooking, space heating, and water heating are supplied with energy also by different sources: • for cooking the energy input consists by large percent by light petroleum gas (LPG) (47.7%), electricity (44.3%) and biomass (8%) (Figure 9). • for space heating diesel (42.7%) has the major contribution in the energy supply followed by biomass (Figure 10). • for water-heating electricity is mainly used (59.7%) but also solar power has a considerable contribution (27.6%) (Figure 11).

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Figure 9 Energy input distribution for cooking

Figure 10 Energy input distribution for space heating

Figure 11 Energy input distribution for water heating

2.1 Industrial and agricultural sectors

The industrial sector has a small contribution in the total energy demand (5%) (Figure 2). The energy demand is mainly provided form HFO (61%), which is used for producing heat (Figure 12). Generally this sector is not developed in Dodecanese islands due to the orientation of local economy to tourism.

The Dodecanese energy system 51

Figure 12 Energy distribution in industrial sector

The agricultural sector also is not developed for the same reasons and has a very small contribution to the total energy demand in the islands (1.8%) (Figure 2). Diesel has the major contribution in the energy supply followed by electricity (Figure 13).

Figure 13 Energy distribution in agricultural sector

2.2 Transportation sector

Transportation is the biggest energy consumer. It contributes 57% in the total energy consumption picture (Figure 2). Gasoline is the basic fuel used for sharing 57% of the total energy demand (Figure 14). The rest 43% come from diesel.

Figure 14 Distribution of energy demand for transportation per fuel

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3 Electricity production and consumption

Electricity is produced mainly in autonomous power stations (APS), which are located in several islands of the Prefecture. The Wind Park of Karpathos is of low installed power and contributes a minor percentage in the satisfaction of the overall energy demand. Also, small photovoltaic units have been installed to cover strictly limited needs (in small residencies and islets). There are three main grids: • Lipsi – – Kalimnos – Kos – Nissiros – • Rhodes – • Karpathos – Kassos. Several other small islands are autonomous and are supplied by individual thermal stations. The fuels used for electricity production for the whole prefecture of Dodecanese are diesel and heavy fuel oil (HFO). HFO has the major contribution to electricity generation (73.7%) (Figure 15).

Figure 15 Distribution of energy input (Tj) for electricity production (1992)

The electricity supply and production for each island is as follows: • Rhodes. The total installed capacity in Rhodes is 145.060 kW. The island Halki is connected to the grid of Rhodes and is supplied by it. • Kalimnos – Kos – Nissiros. The islands Kalimnos, Kos, Leros, Nissiros, Tilos, Lipsi, , and are interconnected and constitute the greater electrical grid of the Prefecture. Electricity is produced by two power stations that are located in the islands of Kalimnos and Kos (net capacity 11,800 and 36,017 kW respectively). Moreover, a third one is located in Nissiros (310 kW), however, after the connection of the island to the Kos, the system remains idle. In order to fulfil the needs of the system a new power station of 50 MW has been constructed and is in operation in Kos. • Karpathos. In Karpathos, the existing power station is operating using diesel fuel and it supplies electricity to Karpathos and the island of Kassos. • . There is a plan to connect this island to the grid of a northern island . The existing power station is going to be shut down. The peak load is going to be covered by a small unit. The power station at present uses diesel fuel.

The Dodecanese energy system 53

• Simi. The electricity needs are covered by a power station producing 1,600 kW using diesel fuel. • – Megisti () – Astipalea. Each of the above-mentioned islands is supplied by autonomous power stations using diesel or heavy fuel oil. None of these islands is interconnected. The annual electricity production in the Dodecanese islands shows continues increase and thus the fuel consumption increase for electricity generation. Based on the annual electricity production and the total annual fuel consumption the overall specific consumption is more or less constant and averages at 0.28 kg fuel (diesel and HFO) per kWh produced (Figure 16).

Figure 16 Annual electricity production and fuel consumption

As mentioned, the basic fuel used for electricity generation is HFO. Its contribution to electricity generation was more less constant but in the year 1998 increased due to the installation of new generators that use HFO in the islands of Rhodes and Kos (Figure 17).

Figure 17 Fuels used for electricity generation (1994–1998)

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Electricity production and consumption in Dodecanese islands has a seasonal behaviour and is fluctuating monthly. Consumption peaks up in the summer months due to tourists influx in that period (Figure 18).

Figure 18 Monthly consumption of electricity for the year 1998

In order to meet the fluctuating demand excess generation capacity is also built into the system for the satisfaction of peak loads. As a consequence, the power system produces electricity at only a fraction of the capacities of its individual plants. The ratio of the actual output of the generating capacity in kWh to the theoretical maximum output of the capacity operating at peak design resource levels is defined as capacity factor. Very low generation capacity factors reflect the serious institutional and operational problems in the investigated power systems. Based on the installed capacity of the APS systems and the annual production, an overall capacity factor of less than 33% is estimated. The characteristics of Autonomous Power Stations vary significantly. In the Prefecture there are only three great Autonomous Power Stations: APS of Rhodes, APS of Kos–Kalimnos (two power stations in the same grid) and APS of Karpathos. In these power stations about 97% of the total annual electricity production is generated, with APS of Rhodes having the major contribution (Figure 19).

Figure 19 Distribution of the electricity produced in Dodecanese islands

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The power stations at Rhodes, Kos and Kalimnos use HFO to cover the base load demand, and diesel to meet peak demand. The other APS systems use only diesel for both base and peak demand. APS of Rhodes is the major consumer of HFO and till the year 1997 the APS of Kalimnos was the second. In the year 1998 Kos has the second place in HFO consumption due to the installation of new generators (Figure 20).

Figure 20 HFO distribution of consumption

Kos and Rhodes had the biggest consumption of diesel for power generation until the year 1977. In the year 1998 however, this pictured changed as the diesel units in these islands were replaced with HFO units or taken out of operation (Figure 21).

Figure 21 Diesel consumption

The annual production elements by APS for the years 1994–1998 are shown in the tables and figures below for each island. There is a continuous increase in the production of energy for each of the islands, for the years 1994 through 1998 that we had data for. For the island of Kalimnos the decrease in power production (Figure 25) is due to the large increase in power production in the island of Kos due to the installation of power engines in the island. Kalimnos, Kos, Nissiros and Tilos are connected in the same grid. In the Figures 22–30, the electricity production and fuel consumption in the APS are showed.

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Figure 22 Electricity production and fuel consumption, APS of Agathonisi

Figure 23 Electricity production and fuel consumption, APS of Astipalea

The Dodecanese energy system 57

Figure 24 Electricity production and fuel consumption, APS of Kalimnos

Figure 25 Electricity production and fuel consumption, APS of Kos

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Figure 26 Electricity production and fuel consumption, APS of Karpathos

Figure 27 Electricity production and fuel consumption, APS of Megisti

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Figure 28 Electricity production and fuel consumption, APS of Patmos

Figure 29 Electricity production and fuel consumption, APS of Simi

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Figure 30 Electricity production and fuel consumption, APS of Rhodes

The capacity of electricity production of each autonomous station and the cost of production differ greatly (Table 1). The cost of electricity production rises for the small capacity units. Due to this high cost it becomes economically feasible to install Renewable Energy Systems (RES) to the small islands. The excess production of electricity of these systems could be channelled to the bigger islands through the grid.

Table 1 Total electricity production and production by APS (1994)

Electricity Peak load Cost Power station Capacity (kW) production (MWh) (kW) (Euro/kWh) Agathonisi 163 0.6989 Astipalea 1,250 2,457 880 0.3644 Kalimnos 11,800 71,064 39,400 0.0526 Karpathos 5,300 16,576 4,550 0.1742 Kos 36,017 80,381 0.11037 Megisti 360 718 200 0.8051 Nissiros 310 The power station is idle Patmos 3,260 7,820 2,480 0.1867 Rhodes 145,060* 396,503 94,000 0.08566 Simi 1,600 5,523 1,370 0.2018 Interconnected system 33,940,663 0.0297 *The value refers to installed capacity and not out-coming capacity.

There is already a movement towards the installation of these systems. There is a wind farm installed in Karpathos (Table 2) that could become a major new supplier of electricity to the island. Small experimental units of Photovoltaic Systems, of capacity 0.7 kW, have been installed in small islets to examine their operation and production for future use (Table 3).

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Table 2 Installed wind turbines/wind farms in Karpathos

1993 1994 1995 Number of wind turbines (WT) 6 Installed capacity of WT (kW) 5 × 55 and 1 × 175* Total installed capacity (KW) 275 (450)* Energy production (MWh) 267 934 185 Penetration level 1.6 5 0.92

Table 3 Individually installed photovoltaic plants

Island Number of PV plants Αlimia 1 Κinaros 1 3 Marathos 5 Nimos 2 Ro 1 Saria 2 Siskli 1 Stroggili 1 Sirna 2

4 Electricity demand projection

The electricity consumption for three uses, domestic, industrial and other, from the year 1990 to 1997 (Figure 31) shows that the distribution of electricity consumption has not changed much through the years. The other uses refer to commercial, hotels, agriculture, public buildings and streets.

Figure 31 Distribution of electricity consumption

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The total consumption of electricity on the other hand has shown a steady increase from the year 1981 through 1997 with an average increase rate of 8.15% (Figure 32). The biggest contribution to the increase is from the ‘other uses’, which is due to the increase in tourism, with average increase rate 9.43%, the domestic consumption follows with an average increase rate of 7.16% and last, the industrial consumption with an average increase rate of 3.67%. The rate of change of annual electricity demand is fluctuating strongly between the years 1981–1996 for the three uses and especially for the industrial demand, but it is always positive for the total demand, showing a continuous increase (Figure 33).

Figure 32 Electricity consumption 1981–1996

Figure 33 Rate of change of annual electricity demand

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The electricity consumption in the domestic sector depends on the population and its standard of living. The electricity consumption per household depends strongly on the number of persons per household and on its ability to accumulate and use electrical devises. In order to evaluate the future electricity demand per household it is logical to assume that the increase rate of the annual electricity consumption will decrease, leading the electricity consumption to saturation. The estimation of the future electricity consumption is based upon the logistic function, which does not increase indefinitely: DH× DH DH(t ) = 0 ∞ +−×−× DH00 (DH∞ DH ) exp(rt ) where DH(t) is the annual electricity consumption at time t, DH0 is the annual consumption for t = 0, DH∞ is the annual consumption at saturation t → ∞ and r is a chance rate. The values of the above constants are determined by regression analysis and the results are presented in Figure 34.

Figure 34 Electricity demand/household projection for Dodecanese Islands

The saturation point is predicted at 5,000 kWh per household (DH∞). The total domestic electricity consumption will depend on the increase of number of households, which is related to the population increase and its standard of living. The domestic electricity consumption for the Dodecanese islands is given by the following equation. TDH(t) = DH(t) × NH (population, economic welfare, t) where, the function NH is the number of households. The estimation of the future number of households is based on the following equation: Population growth NH(t ) = . Number of persons per household The population growth (P(t)) is related to gross domestic product (in EUROS) per capita (GDPC) with the following equation:

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=× × + Paaa(GDPCC )01 exp( GDP ) 2 .

The values of the a0, a1, a2 constants are determined by regression analysis and the results are presented in Figure 35. The evolution of GDPC is estimated using a logistic function. GDP× GDP GDP (t ) = CC0 ∞ C +−×−× GDPCC0C (GDP∞ GDP 0 ) exp(rt )

Figure 35 GDP/capita vs. population

The number of persons per household (h(t)) is correlated with the following equation: =× ×+ ht() b012 exp( b t ) b .

The values of the b0, b1, b2 constants are determined by regression analysis and the results are presented in Figure 36.

Figure 36 Number of persons/household

The total domestic electricity consumption for the Dodecanese islands is then given by the following equation: P(GDP (t )) TDE(tt )=× DH( ) C . ht() The results are presented in Figure 37. The saturation point is at 476 GWh.

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Figure 37 Domestic electricity demand projection for Dodecanese Islands

The commercial-services sector shows a continuous increase and has the largest contribution to GDP (Figure 38). The increasing economic activities in this sector result in the highest contribution to the total electricity consumption (Figure 31).

Figure 38 Contribution to GDP of commercial-services sector

The ratio of GDP (in Euros) produced by the commercial-services and the electricity consumption (GDPE), shows continuous increase (Figure 39) and the estimation of the future values is based on a logistic function. The saturation point is predicted to be at 6.5 Euros/MWh. GDP× GDP GDP (t )= EE0 ∞ . E +−×−× GDP00 (GDPEE∞ GDP ) exp(rt )

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Figure 39 GDP in Euro per MWh electricity consumed in commercial-services sector

The electricity consumption in commercial-services sector is modelled by assuming a linear relationship between the electricity consumption and the GDPE. The results are presented in Figure 40. The saturation point is predicted at 523 GWh.

Figure 40 Electricity consumption in commercial-services sector

The economic activity in the industrial sector shows that no significant development is expected (Figure 41(a)) and there is a decreasing contribution to the GDP (Figure 41(b)).

Figure 41 Industrial sector (a) GDP production and (b) contribution to % GDP

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The electricity consumption in this sector is not expected to increase significantly. The estimation of the future electricity consumption is based upon a logistic function: DIND× DIND DINDI(t ) = 0 ∞ . +−×−× DIND00 (DIND∞ DIDN ) exp(rt ) The saturation point in industrial sector is estimated at 48.3 GWh and the results of the regression analysis are presented in Figure 42.

Figure 42 Industrial sector demand

The results of the above analysis are summarised in Figure 43. According to the estimates deriving by the application of the model the total electricity annual demand will continue to increase. The commercial-services sector is estimated to reach saturation point faster and by the year 2010, 97% of the saturation value will be reached. The projection results are summarised in Table 4.

Table 4 Estimated saturation of consumption

Estimated % saturation Demand Saturation (GWh/yr) 2010 2020 Domestic 476 64 71 Commercial-services 523 97 99 Industrial 48.3 74 84 Total 1047.3 81 86

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Figure 43 Electricity demand projection for Dodecanese Islands

The contribution of the domestic sector to the total electricity consumption, according to the estimates of the model, will decrease initially but as commercial sector will reach saturation, the contribution will start increasing (Figure 44). These results are expected due to the expected increase of tourist activity in the future, in Dodecanese islands.

Figure 44 Percentage contribution to the total future electricity demand

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This work is based on the production and consumption of energy for the years 1981 through 1999. The data that have been collected for the islands of Rhodes and Kos for the years 2000–2002 fit the prediction model well.

5 Conclusions

The increasing touristic activity in the Dodecanese islands has a major contribution to the welfare of the inhabitants and the resulted electricity demand. Because the economy is mainly based on tourism, the major electricity consumption comes from commercial-services sector. According to the estimation made, the demand of commercial-services sector will be saturated more rapidly (99% of saturation up to 2020), but the domestic demand will continue to increase due to the economic growth. The energy demand issue in islands has a specific nature, as small energy production schemes are usually needed and applied, which on the other hand are geographically distributed and incapable of central management in an island cluster. Concerns for the environment and improving the quality of life in island societies are factors that have an ever-increasing influence on the decision-making process in the area of technological development. Technological policies based on the specific nature of islands and an assessment of their resources must be used to address many of the constraints inherent in the island factor. Technology, in broad terms, is considered to be the basis of any initiative for sustainable island development. Fragile island environments require energy production technologies and energy resource management that is ecologically rational, suited to the areas concerned and their resources, and whose impact the environment can be absorbed without profound consequences. The fact that islands economies are so heavily dependent on energy, plus the extra financial, environmental and infrastructure costs that occur by using current, non-renewable energy sources, means that solutions must be sought in the context of technological flexibility and in an increased contribution of renewable energy sources in the energy balance of the islands. Integrated systems are necessary on an island planning scale, in order to provide a feasible territory for sustainable development, bearing in mind social and economic development with energy demands, environmental protection, resource management, land-use control and infrastructure development. Islands are also an ideal case for pursuing sustainable development strategies because of the high level of interdependence between economy, society, and environment, combined with the autonomy of each island territory.

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