A multidisciplinary approach for an effective and rational energy transition in Crete Island, Greece.

This article proposes a mixture of actions for the development of an effective and rational energy transition plan for all sectors and for all types of onshore final energy use in Crete. Energy transition is initiated with an appropriate capacity building campaign. The plan is based on the introduction of energy saving measures and the exploitation of all the locally available energy resources (wind, solar, geothermal potential, biomass), integrated in a cluster of centralized and decentralized power plants and smart grids to produce electricity and heat and for the transition to e-mobility. The core of the energy transition in Crete will be a set of 14 wind parks and Pumped Hydro Storage systems (PHS) for electricity generation and 12 Combined Heat and Power plants, properly designed and dispersed in the insular territory. Economic analysis is executed for the proposed essential power plants on the island. Biomass, solar and geothermal potential can cover the heating demand in Crete several times. Heat can be produced with a specific cost of 0.05 EUR/kWhth from cogeneration plants fired with solid biomass and biogas. The wind parks-PHS systems exhibit payback periods of approximately 10 years with a final electricity selling price at 0.12 EUR/kWhel. The article shows that 100% energy transition in Crete constitutes a feasible target

Computational Simulation and Dimensioning of Solar-Combi Systems for Large-Size Sports Facilities: A Case Study for the Pancretan Stadium, Crete, Greece

The article examines the introduction of solar-combi systems in large-size sports facilities. The examined solar-combi systems consist of solar collectors, a biomass heater and thermal storage tanks. In a sense, they constitute hybrid thermal power plants. The full mathematical background is presented on the operation of such systems, along with a proposed operation algorithm, aiming at the maximization of the captured solar radiation. A case study is implemented for the coverage of the thermal energy needs for hot water production and swimming pools heating, met in the Pancretan Stadium, Crete, Greece. In this way, the article aims to indicate the technical and economic prerequisites that can guarantee the feasibility of the examined systems, highlighting the significant potential contribution of such systems towards the realization of energy transition plans from fossil fuels to renewables. The economic feasibility of the introduced system is based on the avoiding diesel oil and electricity procurement cost, consumed for the coverage of the thermal energy demands under consideration. The optimum dimensioning of the examined case study results to an annual thermal energy demand coverage balance of 55% by the solar collectors and 45% by the biomass heater, giving a payback period of 5–6 years

Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete

This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the solar collectors. An automation system is also designed and proposed for the realization of the newly introduced algorithm. The solar-combi system is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m2 of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available solar radiation in the specific area, the proposed solar-combi system can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWhth

Concentrating Solar Power Advances in Geometric Optics, Materials and System Integration

In this paper, the technological advances in concentrating solar power are reviewed. A comprehensive system approach within this scope is attempted to include advances of highly specialized developments in all aspects of the technology. Advances in geometric optics for enhancement in solar concentration and temperature are reviewed along with receiver configurations for efficient heat transfer. Advances in sensible and latent heat storage materials, as well as development in thermochemical processes, are also reviewed in conjunction with efficient system integration as well as alternative energy generation technologies. This comprehensive approach aims in highlighting promising concentrating solar power components for further development and wider solar energy utilization

A Comprehensive Analysis of Wind Turbine Blade Damage

The scope of this article is to review the potential causes that can lead to wind turbine blade failures, assess their significance to a turbine’s performance and secure operation and summarize the techniques proposed to prevent these failures and eliminate their consequences. Damage to wind turbine blades can be induced by lightning, fatigue loads, accumulation of icing on the blade surfaces and the exposure of blades to airborne particulates, causing so-called leading edge erosion. The above effects can lead to damage ranging from minor outer surface erosion to total destruction of the blade. All potential causes of damage to wind turbine blades strongly depend on the surrounding environment and climate conditions. Consequently, the selection of an installation site with favourable conditions is the most effective measure to minimize the possibility of blade damage. Otherwise, several techniques and methods have already been applied or are being developed to prevent blade damage, aiming to reduce damage risk if not able to eliminate it. The combined application of damage prevention strategies with a SCADA system is the optimal approach to adequate treatment

Criteria-Based Model of Hybrid Photovoltaic–Wind Energy System with Micro-Compressed Air Energy Storage

Utilization of solar and wind energy is increasing worldwide. Photovoltaic and wind energy systems are among the major contributing tec4hnologies to the generation capacity from renewable energy sources; however, the generation often does not temporally match the demand. Micro-compressed air energy storage (micro-CAES) is among the low-cost storage options, and its coupling with the power generated by photovoltaics and wind turbines can provide demand shifting, modeled by efficient algorithms. A model based on criteria that are preset according to the demand is presented. The model decides on the distribution of the generated energy, depending on the state of the energy storage and the preset criteria of each storage technology. The satisfaction of the demand by the energy production and micro-CAES is compared to that of storage batteries. The demand originates in a case study of a household and optimal configurations of photovoltaics and wind turbines, and the storage capacities and costs are compared. An optimal configuration of 30 photovoltaic panels and two wind turbines was found for micro-CAES. The annual stored energy of micro-CAES was 114 kWh higher than that of the system with batteries

Combined Operation of Wind-Pumped Hydro Storage Plant with a Concentrating Solar Power Plant for Insular Systems: A Case Study for the Island of Rhodes

Insular power systems are a special case of infrastructure for power production due to their particular land morphology with extensive hills and ridges. For a higher renewable energy share in the power production, a dedicated design according to local constraints is required. The high wind and solar resources of such cases can be utilized with offshore wind turbines and concentrating solar power, respectively. In addition, pumped-hydro storage is a mature and suitable technology for such terrain. A case study is presented in the island of Rhodes to obtain a renewable energy penetration higher than 70%. The technical and financial requirements for this implementation support the design of this system, while the introduction of concentrating solar power enables significant energy savings during the periods of peak demand of the island. An annual RES penetration close to 80% can be achieved with the combined operation of both plants. The economic viability of the required investment can be ensured with selling prices of the produced electricity in the range of 0.20 EUR/kWh

Combined Operation of Wind-Pumped Hydro Storage Plant with a Concentrating Solar Power Plant for Insular Systems: A Case Study for the Island of Rhodes

Insular power systems are a special case of infrastructure for power production due to their particular land morphology with extensive hills and ridges. For a higher renewable energy share in the power production, a dedicated design according to local constraints is required. The high wind and solar resources of such cases can be utilized with offshore wind turbines and concentrating solar power, respectively. In addition, pumped-hydro storage is a mature and suitable technology for such terrain. A case study is presented in the island of Rhodes to obtain a renewable energy penetration higher than 70%. The technical and financial requirements for this implementation support the design of this system, while the introduction of concentrating solar power enables significant energy savings during the periods of peak demand of the island. An annual RES penetration close to 80% can be achieved with the combined operation of both plants. The economic viability of the required investment can be ensured with selling prices of the produced electricity in the range of 0.20 EUR/kWh

Electricity supply on the island of Dia based on renewable energy sources (R.E.S.)

This paper presents a methodology for determining the specifications of an isolated R.E.S. power production system on an environmentally sensitive ecosystem. The wind and solar power constitute the primary power generation system and diesel generators act as backup. Real wind and solar potential measurements are used. The wind atlas of the island has been constructed. The specifications of the proposed system are optimized by the life cycle cost method. The renewable energy sources (R.E.S.) total annual energy production exceeds 90%. As a result, the dependence on the diesel generator set annual energy production is limited and the system's operational cost is not practically influenced by the increasing fossil fuel prices. The introduction of a small size desalination plant for the production of drinkable water is also investigated. Both the available R.E.S. potential and the minimization of environmental impacts are considered for the siting of the equipment. The methodology of the present paper may be applied to other regions rich in R.E.S. potential, where the introduction of small size environmentally friendly isolated R.E.S. power systems is investigated.Wind Photovoltaic Renewable Energy Power Hybrid