Soft energy sources in regional energy systems: The case of the Cyclades

We evaluate the potential penetration of renewable energy sources in the region of the Cyclades, which is a complex of Greek islands in the Aegean Sea. The Cyclades area has a significant endogenous potential of wind, solar and geothermal energy. Future energy demand is forecast for two paths. RESOM, a linear programming regional energy optimization model, has been adapted to represent the regional energy system. The results of four scenario runs provide insight on the impact of renewable energy sources.     

Optimal wind-hydro solution for Aegean Sea islands' electricity-demand fulfilment

Energy shortage and clean-water deficit, especially during the summer, are among the main factors delaying the economic development of Aegean Sea islands. All these islands possess an outstanding wind potential. However, the stochastic behaviour of wind speed leads to significant disharmony between wind energy production and electricity demand. Hence, the prospect of creating a combined wind-hydro energy production station is found to be a vital solution for all these islands, under the preconditions of maximum energy autonomy and limited first installation cost. Accordingly, a methodology of optimal wind-hydro solution estimation is developed and subsequently applied to several typical Aegean Sea island cases, in order to define the most beneficial configuration of the proposed renewable station. All numerical calculations are based on real data, like long-term wind speed measurements, demanded electrical-load and operational characteristics of the system components. In all cases analyzed, the renewable energy sources penetration exceeds 85%, while a significant part of the system's wind energy surplus is forwarded to a desalination plant for clean-water production.     

Energy design investigation for the Greek area of the North Aegean Sea

This paper describes an investigation of the energy design in the area of the North Aegean Sea. The future energy consumption is predicted until 2010 using simple statistic models for each economic sector such as domestic, tertiary and agricultural, transport, industry, etc. Three different energy design scenarios have been developed for predicting the energy consumption for each economic sector. These scenarios present three major energy evolutions: a conventionally expected energy evolution (business as usual); an energy saving evolution; and a combination of energy saving with simultaneous exploitation of renewable energy sources. The energy design investigation for the area of the North Aegean Sea is mainly based on simple statistic analysis on data describing the energy balance for each economic sector and kind of energy use. This energy balance analysis for the area of the North Aegean Sea has been performed in the present study in order to be furthermore used in the energy design investigation.     

Renewables portfolio,individual preferences and social values towards RES technologies

The massive deployment of renewable energy sources represents a high priority for Greece in order to comply with the Directive 2009/28/EC on the promotion of the use of energy from renewable sources by 2020. In this perspective, Aegean islands especially Lesvos, are endowed with a considerable potential of a portfolio of renewables, a fact that the entrepreneurial interest has already been targeted. However, regulatory attempts for a massive penetration of renewables do not take seriously into account preferences and risk perceptions of local communities where the proposed projects are to be installed. The aim of this study is to investigate individual preferences and social values towards specific technologies of renewables in Lesvos island. We apply an open-ended contingent valuation survey in order to analyze factors shaping public attitudes towards a portfolio of renewable technologies and estimate the economic welfare (Willingness To Pay) of the preferred technologies. We argue that such information is relevant for energy policy design and the establishment of effective measures for the promotion of renewable energy sources.     

Present situation and future prospects of electricity generation in Aegean Archipelago islands

The Aegean Archipelago is a remote Hellenic area, including several hundreds of scattered islands of various sizes. In these islands more than 600,000 people are living mainly in small remote communities. The main economical activities of the islanders are apart from tourism, seafaring, fishery, agriculture and stock farming. One of the major problems of the area is the insufficient infrastructure, strongly related with the absence of an integrated and cost-effective electrification plan. In this context, the present work is concentrated on analyzing the present situation and demonstrating the future prospects of electricity generation in the Aegean Archipelago islands. For this purpose, one should first investigate the time evolution of the corresponding electricity generation parameters (i.e. annual electricity consumption, peak power demand, capacity factor, specific fuel consumption) for the last 30 years. Subsequently, the corresponding diesel and heavy-oil consumption along with the electricity production cost for every specific autonomous power station of the area are investigated. Special attention is paid in order to estimate the contribution of renewable energy sources (RES) in the energy balance of each island. Finally, an attempt is made to describe in brief the most realistic electricity production solutions available, including the operation of hybrid RES-based power plants in collaboration with appropriate energy storage facilities. Additionally, the idea of connecting the islands of the area with the mainland and interconnecting them is also taken into consideration.     

Optimum energy storage techniques for the improvement of renewable energy sources-based electricity generation economic efficiency

The high wind and solar potential along with the extremely high electricity production cost met in the majority of Greek Aegean islands comprising autonomous electrical networks, imply the urgency for new renewable energy sources (RES) investments. To by-pass the electrical grid stability constraints arising from an extensive RES utilization, the adaptation of an appropriate energy storage system (ESS) is essential. In the present analysis, the cost effect of introducing selected storage technologies in a large variety of autonomous electrical grids so as to ensure higher levels of RES penetration, in particular wind and solar, is examined in detail. A systematic parametrical analysis concerning the effect of the ESSs’ main parameters on the economic behavior of the entire installation is also included. According to the results obtained, a properly sized RES-based electricity generation station in collaboration with the appropriate energy storage equipment is a promising solution for the energy demand problems of numerous autonomous electrical networks existing worldwide, at the same time suggesting a clean energy generation alternative and contributing to the diminution of the important environmental problems resulting from the operation of thermal power stations.     

Techno-economic comparison of energy storage systems for island autonomous electrical networks

The oil-dependent electricity generation situation met in the Aegean Archipelago Islands is in great deal determined by increased rates of fuel consumption and analogous electricity production costs, this being also the case for other island autonomous electrical networks worldwide. Meanwhile, the contribution of renewable energy sources (RES) to the constant increase recorded in both the Aegean islands’ annual electricity generation and the corresponding peak load demand is very limited. To compensate the unfavorable situation encountered, the implementation of energy storage systems (ESS) that can both utilize the excess/rejected energy produced from RES plants and improve the operation of existing thermal power units is recommended. In the present study, a techno-economic comparison of various RES-ESS configurations supported by the supplementary or back-up use of existing thermal units is undertaken. From the results obtained, the shift of direction from the existing oil-dependent status to a RES-based alternative in collaboration with certain storage technologies entails – apart from the clear environmental benefits – financial advantages as well.     

Increasing renewable energy sources in island energy supply: case study Porto Santo

While the energy supply of most islands depends mainly on expensive oil derivatives’ importation, the others are linked by usually a weak electricity grid connection to the mainland. Due to high energy costs the islands are proving to be excellent test beds for the introduction of new technologies, and some islands are trying to become so-called renewable islands, to satisfy their energy demand mainly or entirely from indigenous and renewable sources, thus increasing the security of supply, and employment opportunities, without necessarily increasing the costs. Islands that have energy sources, such as hydro or geothermal energy, can easily integrate them into the power system, but those with mainly intermittent renewable energy sources are confronted with the necessity of energy storage. The most promising technologies are reversible hydro where geography allows, and storing hydrogen where it does not. The stored hydrogen can later be used for electricity production, and also for transport. This paper describes the H₂RES model for optimisation of integration of hydrogen usage with intermittent renewable energy sources on the example of an isolated island in the Madeira archipelago, Porto Santo. It shows that it is possible to significantly increase the penetration of renewable energy sources, albeit at a relatively high cost, with hydrogen storage technology. The H₂RES model, which includes reversible hydro and batteries as storage technologies, can serve as a valuable tool for island energy planning.     

Renewislands—Renewable energy solutions for islands

Increase of the global energy demand and environmental problems relating to fossil energy utilization request the new energy sources to replace the traditional fossil fuels. With respect to energy production, most of the islands in European Union and in the other parts of the world, depend on importation, mainly from oil and its related products. The global development of renewable energy technologies can assure sustainable supply of power for islands. To overcome the limitation of the sources of renewable energy, hydrogen is utilized as a storage medium integrated with intermittent renewable energy sources such as wind and solar. This paper introduces the programme of “Renewislands—Renewable Energy Solutions for Islands”, the work tasks, details of the design of the activities to develop solutions integrating intermittent renewable energy supply (RES), fuel cell (FC) and hydrogen infrastructure to promote RES and innovative decentralized power systems penetration in islands; main results achieved in each work packages are presented; in addition, the development of intermittent renewable energy penetration in specific European Islands are reviewed briefly.     

Techno‐economic and environmental analysis for grid interactive solar photovoltaic power system of Lakshadweep islands

The Lakshadweep group of islands in Arabian Sea is one of the two major groups of islands in India. In these islands the main source of electricity is diesel generators, the diesel being transported from the main land to produce over 9 MW of electricity. Considering the remoteness of the island and the polluting nature of the existing plants, it is desirable to adopt a strategy to utilize available potential of non‐polluting renewable energy sources for these ecologically sensitive islands. A techno economic and environmental analysis for grid interactive solar photovoltaic power system of Union Territory of Lakshadweep islands is presented. This paper also examines the pollution aspect of power generation through Diesel Generator set and highlights the environmental benefits in using solar energy. Experiences of grid interactive solar photovoltaic power system installed recently in different islands are discussed and suggestions have been made for improving its efficiency and performance. Copyright © 2004 John Wiley & Sons, Ltd.     

Stable power supply of an independent power source for a remote island using a Hybrid Energy Storage System composed of electric and hydrogen energy storage systems

We propose a self-sustaining power supply system consisting of a “Hybrid Energy Storage System (HESS)” and renewable energy sources to ensure a stable supply of high-quality power in remote islands. The configuration of the self-sustaining power supply system that can utilize renewable energy sources effectively on remote islands where the installation area is limited is investigated. It is found that it is important to select renewable energy sources whose output power curve is close to the load curve to improve the efficiency of the system. The operation methods that can increase the cost-effectiveness of the self-sustaining power supply system are also investigated. It is clarified that it is important for increasing the cost effectiveness of the self-sustaining power supply system to operate the HESS with a smaller capacity of its components by setting upper limits on the output power of the renewable energy sources and cutting the infrequent generated power.     

Investigation of hydrogen production potential from different natural water sources in Turkey

Hydrogen production from the electrolysis of water by sea or lake waters used as electrolyte plays a crucial role in providing sustainable hydrogen production. Production of hydrogen from these natural sources is highly utilized from small scale to complex applications due to water resources' inconsumable potential. In this study, the hydrogen production potential of Turkey's different regions such as the Black Sea, Aegean Sea, Marmara Sea, Mediterranean Sea, Lake Van, Ağcaşar Dam, Yeşilırmak, and Kızılırmak rivers are investigated. Solar energy potential values are used as the current sources for simulating their renewable energy hydrogen production values. According to the results, higher hydrogen production rates are obtained from the Marmara and Lake Van regions. It is concluded that the hydrogen production potential is highly dependent on the pH values of the water source and the salinity rate of seawater that is descending from the Mediterranean Sea to the Black Sea region. Besides, solar radiation, sunshine duration, and water temperature are the other essential factors. Moreover, Mediterranean Sea water (Içel-Anamur) has about 23% higher hydrogen production than Lake Van and has the most increased hydrogen production by 80 L m^-2 in May and June.     

Short-term forecasting of wind speed and related electrical power

Wind speed and the related electrical power of wind turbines are forecasted. The work is focused on the operation of power systems with integrated wind parks. Artificial neural networks models are proposed for forecasting average values of the following 10 min or 1 h. Input quantities for the prediction are wind speeds and their derivatives. Also, spatial correlation of wind speeds and its use for forecasting, are investigated. The methods are tested using data collected over seven years at six different sites on islands of the South and Central Aegean Sea in Greece.     

Energy policy and an action plan for renewable energy sources (RES) for the Hellenic islands of the North Aegean region

The resource base for RES is vast, but only a small fraction is being exploited with available technology. The full potential of RES for the European Union (EU) is estimated at 408 Mtoe by 2020. Here, we review data on energy supplies and demand with emphasis on RES and also assess the potential for energy conservation by using RES in remote regions. Our case study deals with the Hellenic islands of the North Aegean region. These islands have a high RES potential because of their dependence on external energy sources, absence of control over fossil-fuel costs and periodic power shortages, especially during summers when energy demands peak as a result of tourism.     

Multi-objective optimisation of renewable energy systems for pollution mitigation – a case study of Kavaratti Island,India

Islands represent a unique challenge in terms of electrical energy supply. A great deal of work has been carried out on this specific aspect of energy supply on different islands in the world. Unfortunately, due to island-specific energy usage profile, resources and different kinds of environmental conditions, a study of one island cannot be easily extended to other islands. The Lakshadweep group of islands in the Arabian Sea is one of the two major groups of islands in India having diesel generators (DGs) as the main source of electricity. Considering the remoteness of the island and the polluting nature of existing DGs, it is desirable to adopt a strategy to utilise the available potential of non-polluting renewable energy sources (RESs) for these ecologically sensitive islands. A multi-objective optimisation methodology is applied in Kavaratti Island, Lakshadweep, where various RESs exist and can be exploited to generate electrical energy and to mitigate environmental pollution. A specific mathematical model is developed with two objective functions, namely cost and environmental pollution that work reversibly. Application of the proposed mathematical tool leads to a Pareto set, satisfying the multiplicity of criteria, namely environmental pollution, energy demand, per-unit generation cost and resource constraints.     

Combining hydro and variable wind power generation by means of pumped-storage under economically viable terms

Pumped hydro storage (PHS) systems which are located at isolated regions and are able to exploit the rejected wind energy amounts produced by local wind farms, seem to gain interest worldwide and to become essential in regard to higher shares of renewable-generated electricity. Despite the high wind potential encountered in many Greek island regions, the wind energy contribution to the electrification of these areas is significantly restricted due to imposed electrical grid limitations. In this context, the current work examines the economic viability of a wind-based PHS system (wind-hydro solution) which provides the local electrical grid of an Aegean Sea island, Lesbos, with guaranteed energy amounts during the peak load demand periods. Based on the maximization of the project’s net present value, the optimum system configuration is proposed while many other feasible solutions are revealed. According to the results obtained the implementation of this project demonstrates excellent technical and economic performance, while at the same time renewable energy sources (RES) contribution is doubled reaching almost 20% of the Lesbos island electrical energy consumption.     

Increasing the penetration of renewable energy resources in S. Vicente,Cape Verde

In this article different scenarios are analysed with the objective of increasing the penetration of renewable energies in the energy system of S. Vicente Island in Cape Verde. An integrated approach is used to analyse the electricity and water supply systems. The H₂RES model, a tool designed to simulate the integration of renewable sources and hydrogen in the energy systems of islands or other isolated locations, is applied.     

Wave energy potential in the Baltic Sea and the Danish part of the North Sea, with reflections on the Skagerrak

Wave power, along with renewable energy-generating sources like tides and streams, is underestimated considering its advantageous physical properties and predictability. This paper examines possible examples of wave power installations in the Baltic Sea and the Danish part of the North Sea. Hindcasting data is used allowing estimations of wave energy generated and results show promising areas in the North Sea, but also several parts of the Baltic Sea are of interest. The study is based upon linear generator technique, placed on the seabed using point-absorbers arranged in arrays of up to several thousand units. The study aims at showing the physical possibilities of wave energy, including economical feasibility and environmental advantages of wave energy even in moderate wave climates. With discussion from two examples in the Baltic Sea, one in the Danish North Sea and a new pilot study site in the Swedish part of Skagerrak, this study show feasible illustrations of wave energy takeouts. Project examples vary in size due to distance to grid, grid voltage, and may thus be economically feasible. Examples also show considerations in societal and nature conservation matters, including aspects such as industrial and military interests, archaeological or marine reserves and local geology. The authors conclude that wave energy electric conversion is an option that needs more attention and which has several advantages compared to conventional renewable sources. Sound engineering, in combination with producer, consumer and broad societal perspective is advised for a sustainable development of wave energy conversion.     

Hydrogen as an energy vector in the islands’ energy supply

Hydrogen as an energy vector can increase penetration of renewable and intermittent sources in the energy supply of the islands and it can serve as an energy vector that may allow reaching 100% renewable energy supply of island communities. This article presents summary of the results of several case studies: Island of Mljet—Croatia, Porto Santo—Madeira, Terceira—Azores, and Malta. The islands were analysed by RenewIslands methodology and it was decided to apply hydrogen as an energy vector. Different scenarios for each island were modelled by H₂RES software and required installed powers of necessary technological options are described for chosen scenarios.     

A simulation-optimisation programme for designing hybrid energy systems for supplying electricity and fresh water through desalination to remote areas: Case study: the Merssini village,Donoussa island,Aegean Sea,Greece

The aim of the present paper is to develop and apply a software tool for designing hybrid renewable energy systems. The hybrid system consists of a wind generator and photovoltaic modules which are the renewable technologies for energy production. The programme has been applied for simulating a hybrid system with the above mentioned technologies in order cover the electricity and water needs of the Merssini village on Donoussa island in the Aegean Sea of Greece. The Merssini village is occupied by 20 year-round residents while the population is doubled during the summer period. The village is non-electrified and faces a problematic scarcity of fresh water. In the analysis that follows, the considered technical data as well as the results of programme runs for winter and summer seasons are presented. The electricity consumption consists of both the household and desalination plant consumption. The system is supplemented with batteries and a micro hydraulic plant for energy storage. The simulation programme was used to optimise the design of the system as well as to manage the energy supply and energy storage. The results prove that this simulation programme constitutes a valuable tool for the determination not only of the optimum combination of technologies, but also the optimum energy management of complex hybrid systems.