K. Kavadias

Evaluation of the wind–hydro energy solution for remote islands

Abstract The possibility to create a combined wind–hydro energy station in a medium size island of the Aegean Archipelago is investigated on a techno-economic basis. The proposed solution may be used to face the extremely high electricity production cost in these regions, taking also advantage of the excellent local wind potential. Additionally, a parametrical analysis is performed on a techno-economic basis in order to select the appropriate number of wind turbines and the optimum size of water reservoirs. The calculation results obtained, based on real measurements and on experimental data, validate the proposed solution. More precisely, the electricity demand of the remote system is covered in any case, the imported fuel is minimized, the renewable energy sources penetration exceeds 90%, and the negative environmental effects are remarkably reduced.

Energy and clean water coproduction in remote islands to face the intermittent character of wind energy

In many small- or medium-sized remote islands, there is a significant electrical power shortage, where the water resources are quite limited. This unfavourable situation results in the operation of high cost autonomous thermal power stations and the transportation of fresh water of questionable quality at extremely high prices. Wind energy can definitely contribute on solving these problems at a rational investment and operational cost. To face the intermittent and stochastic wind behaviour, a combined wind-hydro configuration is proposed in collaboration with an appropriate desalination plant. The proposed solution leads to high wind energy penetration rates and bounds the operational hours of the existing internal combustion engines, additionally contributing to the air pollution reduction. Besides, significant water quantities can be produced, remarkably reinforcing the water reserves of the local community with fresh water of desired quality. Consequently, the configuration investigated can efficiently fulfil the electrical energy and the clean water requirements of numerous remote communities on the basis of clean and low cost wind energy, overcoming the intermittent and stochastic behaviour of the wind.

An Optimum Sizing Methodology for Combined Photovoltaic-Energy Storage Electricity Generation Configurations

The electrification of autonomous electrical networks is in most cases described by low quality of electricity available at very high production cost. Furthermore, autonomous electrical networks are subject to strict constraints posing serious limitations on the absorption of renewable energy sources (RES)-based electricity generation. To bypass these constraints and also to secure a more sustainable electricity supply status, the concept of combining photovoltaic (PV) power stations and energy storage systems comprises a promising solution for small scaled autonomous electrical networks, increasing the reliability of the local network as well. In this context, the present study is devoted in developing a complete methodology able to define the size of an autonomous electricity generation system, based on the maximum available solar potential exploitation at mini- mum electricity generation cost. In addition special emphasis is given in order to select the most cost-efficient energy storage confcguration available. According to the calculation results obtained, one may clearly state that an optimum sizing combination of a PV generator along with an appropriate energy storage system may significantly contribute on reducing the electricity generation cost in several island electrical systems, providing also abundant and high quality electricity without the environmental and macroeconomic impacts of the oil-based thermal power stations.

The Contribution of Renewables on Reducing the Electricity Generation Cost in Autonomous Island Networks

The Aegean Archipelago is a remote Hellenic area, including several hundreds of scattered islands of various sizes. The electricity demand in the Aegean Archipelago islands has up to now been covered by the existing autonomous power stations (APS) at very high electricity production cost. In order to face the continuous load demand increase an integrated solution based on the exploitation of the available renewable energy sources potential in collaboration with appropriate energy storage systems is investigated. According to the results obtained, the proposed solution is clearly more cost-effective than the operation of the existing thermal power stations, while remarkable environmental and macroeconomic benefits are also expected.

The role of hydrogen-based energy storage in the support of large-scale wind energy integration in island grids

To confront problems concerning large-scale integration of renewable energy sources, introduction of energy storage constantly gains ground. Benefits stemming from the adoption of energy storage include exploitation of otherwise rejected energy, increased reliability of energy supply and improved operation of a given power system overall. In this regard, contribution of such systems in achieving large-scale integration of wind energy into island grids is currently considered. More precisely, fuel cells and hydrogen storage (FC–HS) are investigated, in comparison with conventional batteries. For this purpose, a simulation algorithm is developed to study the energy performance of different FC–HS configurations used to recover wind energy curtailments. The developed algorithm is then applied to a representative Aegean island of medium–high quality wind potential. Results obtained indicate that FC–HS may become attractive in comparison with conventional batteries, only in the case that the use of hydrogen surplus to cover other energy flows is also put forward.

Energy performance evaluation of a hybrid system in the Athos State

Based on the use of long-term energy measurements for an entire year, obtained from a hybrid station operating in the Monastery of “Simonos Petras” in Northern Greece, evaluation of the system energy management plan is presently carried out. The hybrid system under investigation comprises of a hydropower station, a photovoltaic (PV) generator and a diesel engine, while the entire installation is also supported by the employment of a battery bank. According to the analysis of results obtained, reassessment of the current energy management plan is as proved necessary in order to raise restrictions posed to the energy contribution of the PV generator. For this purpose, the theoretical maximum energy contribution of the PV generator is estimated and replacement of the diesel engine operation is explored, with results obtained being rather encouraging for the system future operation.

Integrated Studies on Renewable Energy Sources. The Soft Energy Application Laboratory, Mechanical Engineering Department, TEI of Piraeus

Publisher Summary This chapter discusses integrated studies on renewable energy sources. The potential of Renewable Energy Sources is very significant in Greece. An important number of applications in wind energy, solar energy, hydropower, biomass, and geothermy are either under development or under scheduling. Emphasis is laid to include not only technical but also economical and socio-environmental factors during the implementation of similar plans. The Soft Energy Application Laboratory of TEl Piraeus supports an integrated program concerning the studies on Renewable Energy Sources, including theoretical knowledge and laboratory work. Additional courses are also offered concerning Environment Protection, Environmental Technology, Management of Natural Sources, and Feasibility Analysis, social cost included. A wide-ranging circle of courses on Soft Energy Applications and Environmental Protection Technologies is, also, the basis for the new sector of the Mechanical Engineering Dept., whose operation is going to start in the next academic semester. Finally, the goal is to prepare young engineers and technical managers with an aim to contribute to the National and European effort in order to accelerate the penetration of RES in the energy market with huge financial, environmental, and social benefits.