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There are regions in the Republic of Croatia (underdeveloped, devastated by war, depopulated, as well as islands and mountainous areas) which are still disconnected from the electricity network or where the current network capacity is insufficient. In addition, these regions have good renewable energy potential. Since the decentralized energy generation (DEG) covers a broad range of technologies,...
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...
A stand-alone power system that consists of a photovoltaic array and wind generators for the exploitation of renewable energy sources (RES), and that is capable of storing excessive energy in the form of hydrogen via water electrolysis for subsequent use in a polymer electrolyte membrane (PEM) fuel cell is currently being installed at Neo Olvio of Xanthi in Greece. The performance of two power management...
Unlike the present energy system based on fossil fuels, an energy system based on renewable energy sources with hydrogen and electricity as energy carriers would be sustainable. However, the renewable energy sources in general have less emergy than the fossil fuels, and their carriers have lower net emergy. Because of that they would not be able to support continuous economic growth, and would eventually...
The first Romanian passive office building has been constructed by the AMVIC Company in Bragadiru, 10 km south of Bucharest. The overheating rate and the cooling load are higher for a passive building than for a standard building. The internal heat sources and the maximum allowed indoor temperature do markedly affect the cooling load. A time-dependent model shows that cooling is necessary during April-September...
The paper presents the stochastic optimization algorithm that may eventually be used by electric energy suppliers to coordinate charging of electric-drive vehicles (EDVs) in order to maximize the use of renewable energy in transportation. Due to the stochastic nature of transportation patterns, the Monte Carlo simulation is applied to model uncertainties presented by numerous scenarios. To reduce...
The present article analyses the effects caused by variable power. The analysis concerns a country-scale electricity system with a relatively high penetration of seasonally variable hydro power plants and wind farms in the total electricity generation in 2030. For this purpose, the Latvian electricity system was chosen as an appropriate case study, as around half of its electricity is already generated...
The building sector is one of the largest energy consumers. Even though cooling needs do not contribute a large share to the overall energy demand in temperate climates, recent trends show a tendency of large growth. This growth is related to two main drivers: cheap and affordable air-conditioning units that have overrun the market and the more frequent occurrence of hot and extremely hot weather...
This paper analyzes the concept of a decentralized power system based on wind energy and a pumped hydro storage system in a tall building. The system reacts to the current paradigm of power outage in Latin American countries caused by infrastructure limitations and climate change, while it fosters the penetration of renewable energy sources (RES) for a more diversified and secure electricity supply...
Hybrid renewable power generation systems considering storage of energy and/or hydrogen involve considerable complexity as heterogeneous equipment need to be interconnected and activated or deactivated at different time instances. This work employs generic and flexible decision making models to develop complex power/hydrogen management strategies and investigate their performance on systems integrating...
The scope of this article is to investigate the effects of introducing a WP-PSS (Wind Powered Pumped Storage System) in isolated electricity systems assuming unfavourable conditions such as low onshore wind potential and low PSS head height. These disadvantages can be compensated with the installation of offshore wind parks, larger reservoirs and double penstocks to allow simultaneous water fall and...
The variable electricity output of the RES (renewable energy sources) power plants, such as wind and hydropower, is an important challenge for the electricity system managers. This paper addresses the problem of an electricity system supported mainly on hydro, thermal, and wind power plants. A binary mixed integer non-linear optimization model with hourly time step is described. The model is applied...
The growing concerns about climate change and security of supply opened way to a significant investment in the exploitation of RES (renewable energy sources) for electricity generation. The possibility of achieving 100% RES systems is being debated but concerns about costs, storage and backup capacity still prevail. This paper addresses the topic of renewable energy scenarios for the electricity sector,...
The integration of large amounts of variable renewable generation can increase the demand on flexible resources in the power system. Conventional hydropower can be an important asset for managing variability and uncertainty in the power system, but multi-purpose reservoirs are often limited by non-power constraints. Previous large-scale variable generation integration studies have simulated the operation...
This paper presents the possibility of exploiting low-temperature heat from the generators' cooling system within a hydro power plant, using a HTHP (high temperature heat-pump) that enables heating at up to 85 °C.The results based on theoretical calculations are presented for heat-flows, the powers of the compressors, and COP (coefficient of performance) values for the cases when using the refrigerant...
Development of the utilisation of renewable energy sources and energy efficiency represents the main policy for sustainable development. The overall target of the European Union Directive on the promotion of the use of energy from renewables (RES) is to achieve at least a 20% share of energy from renewables in the gross final energy consumption in 2020. The mandatory national target for Slovenia is...
A hybrid energy system, based on renewable energy sources and with hydrogen storage, can become an alternative for stand-alone electricity and heat supply. The objective of this work is to evaluate the feasibility of a completely renewable supply of power and heat for an isolated household, and a comparison to reference and alternative energy supply scenarios. In this paper, an energy system using...
This article examines different passive and active heating systems for swimming pools. The passive systems introduced in this article are:* The swimming pools' enclosure.* The placement of floating insulating covers on the pools' surfaces whenever they are not used.The examined active systems in this article are:* A biomass heater.* A biomass heater and solar collectors combi-system.* Vertical geothermal...
In this study, different effects of EVs (electric vehicles)/PHEVs (plug-in hybrid electric vehicles) with V2G (vehicle-to-grid) connection capability and renewable energy sources used as DGs (distributed generators) on a power distribution network are analyzed. A power distribution network including CPGs (conventional power generators) located in powerhouses, different types of renewable energy sources...
The current energy policy requires a constant technology development towards more sustainable energy transformation systems. Cogeneration and the use of renewables are two important solutions available to achieve this goal. If cogeneration is applied locally, e.g. as CHP (combined heat-and-power generation) modules with internal combustion engines, it leads to additional advantageous effects due to...
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