The technical analysis of a hybrid wind-photovoltaic energy system with hydrogen gas storage was studied. The market for the distributed power generation based on renewable energy is increasing, particularly for the standalone mini-grid applications. The main design components of PV/Wind hybrid system are the PV panels, the wind turbine and an alkaline electrolyzer with tank. The technical analysis is based on the transient system simulation program TRNSYS 16. The study is realized using the meteorological data for a Typical Metrological Year (TMY) for region of Novi Sad, Belgrade cities and Kopaonik national park in Serbia. The purpose of the study is to design a realistic energy system that maximizes the use of renewable energy and minimizes the use of fossil fuels. The reduction in the CO2 emissions is also analyzed in the paper.

The raw clay “Klokoti” from middle Bosnia was beneficiated by method of wet separation which results in removing fraction over 20 μm. The raw clay was characterized by chemical composition, grain size distribution and characteristic temperatures on heating microscope. The beneficiated clay was characterized by chemical composition and characteristic temperatures. The phase composition of raw and beneficiated clay was observed by RDA while the microstructure was monitored on scanning electron microscope (SEM). The sintering process was performed at 1100oC, 1250oC, 1320oC and 1400oC with two hours holding time at the highest temperature. The obtained results indicate a big content of coarse quartz in raw clay and gradually increase of crystalline mullite content with increasing temperature of sintering. Beneficiated clay at higher temperature of sintering produces larger glassy phase content, which is result of larger fluxing content in its composition. It is also observed that from beneficiated clay by sintering at 1250°C crystallize the most mullite along with minimum porosity and the lowest glassy phase content.

This paper studies different rotor topologies for the design of a 2 MW doubly-fed reluctance generator for a wind turbine application. There have been several papers that put forward different options for this type of machine and the control has been extensively studied. This paper uses the same stator size and application to enable comparative operation. This machine has two 3-phase winding sets — a 4 pole and an 8-pole arrangement, and a 6-pole reluctance type of rotor. Different designs for the rotor are investigated in terms of either their duct arrangement or solid salient pole structure. The key issue for this machine is the coupling between the stator winding sets.

As a metropolitan city, Belgrade is a dwelling place for about 25% of total citizen number of Republic of Serbia, and at the same time regional cultural, educational, scientific and business center with its own energy production. Belgrade represents a significant consumer of final energy to support the living standard of the occupants. Energy production is based on domestic coal and imported fossil fuels such as oil and natural gas resulting in a high impact to the environment by emission of harmful substances. Multi-criteria method is a basic tool for the sustainability assessment in metropolitan cities. The design of potential options is the first step in the evaluation of buildings. The selection of a number of residential buildings is based on geographic position and type of heating. This paper presents the sustainable assessment of energy system for residential building sector in Belgrade. In order to present the energy system options for residential building sector, three sets of energy indicators: economical, social and environmental are taken into consideration.

The taxonomical relationship between Salvia pratensis and S. bertolonii has been unclear for a long time. Salvia bertolonii has alternatively been considered a synonym, a subspecies, a problematic subspecies and a form of Salvia pratensis. However, both these two species are sometimes used in traditional medicine instead of sage (Salvia officinalis) or as an adulteration for the same drug. In order to confirm the status of S. bertolonii, together with the potential identification characteristics for differentiation from sage, both taxa were analyzed through the analysis of their essential oils, together with the micromorphological characteristics of the leaf surface and the anatomy and morphology of the leaves. The obtained results show that there are clear differences in the quantity of essential oil (0.073% for S. pratensis and 0.0016% for S. berolonii). The major compound in the essential oil of S. pratensis was E-caryophyllene (26.4%) while in S. berolonii essential oil caryophyllene oxide was the major component (35.1%). The micromorphological differences are also pronounced in the leaf indumentum (density and distribution of certain types of non-glandular and glandular trichomes). Clear distinction between the investigated Salvia species is also observed in the leaf anatomy (in S. pratensis leaves are thinner, palisade tissue is made of 1-2 layers of cells, and leaves of S. bertolonii are characterized by 2-3 layers of palisade tissue cells, and consequently thicker).

Development of advanced technology applicable for efficient prevention of heavy earthquake damage and total collapse of existing and new bridges in future earthquakes was challenging motivation of the second author to start with realization of long-term pilot-innovative project entitled: “High Performance Seismic Isolation of Bridges”. The developed new technology for qualitatively improved seismic protection of bridge structures is based on application of the patented “GOSEB3” system for construction of seismically safe structures. Qualitative step of GOSEB3 (generation-3) innovative seismically-resistant bridge system, is created with full multi-level global optimization of seismic energy balance. The innovative project was officially nominated by the Government of the Republic of Macedonia to represent new and advanced national achievements in the field of INVENTIONS AND SCIENCE. The research activities have been continued in the frame of 3-year bilateral scientific project Macedonia-Serbia (2005-2007). The new “GOSEB3” high performance seismic isolation system for bridges, actually represent very important technical innovation capable of integrating the advantages of seismic isolation, seismic energy dissipation and effective displacement control. Furthermore, the new seismic isolation system for bridges based on multi-level seismic energy absorption and optimized seismic energy balance shows very high seismic control performances and can be used for full seismic protection of new and seismic revitalization of existing bridges in longitudinal and in transversal direction under the effect of very strong earthquakes. The present research activities are continued to provide conditions for wide practical application of the invented GOSEB3 seismic isolation system..

Abstract Biomass use for power generation has become an attractive option for the increase of energy production with the increase of efficiency, decrease of environment degradation and waste utilization. Justification of the biomass use benefits requires a multi-criteria assessment based on the evaluation of economic, environmental, technological and social aspects. In this respect, the need for the evaluation of biomass-fired power plant is of great interest for the validation of benefits of biomass resources. The paper presents an outline of a multi-criteria method for the evaluation of the General Sustainability Index as the quality measurement of different potential options of the biomass-fired power plant and their comparison with other new and renewable power plants. A number of options are evaluated with appropriate selection of indicators reflecting economic, environment, technological and social parameters. Among options under consideration there are those reflecting mixed fuel of biomass and fossil organic fuel power plants. Special attention is devoted to the use of constraints giving priority to individual criteria. It is shown that the potential quality merit, which describes the priority of individual options under specific constraint is the potential tool for the energy system evaluation. This decision-making procedure enlightens the potential priority of biomass-fired power plants in comparison with other renewable energy sources.

The size and number of wind farms contributing to the energy production is continuously growing. The rating of wind turbines has increased from less than 1 MW a few years ago to 2- to 3-MW being installed today with 5-MW machines under development. The interaction of the wind farm, reactive power compensators, and the associated power network is being investigated. Because the loads and the wind farms' output fluctuate during the day, the use of reactive power compensation is ideal for the power system network. The purpose of this study is to provide wind farm developers and interested researchers with some valuable insights into the reactive power compensation techniques for wind farm power systems

Solar energy systems are becoming potential option for numerous applications. It has been shown that the application of solar energy system is strongly dependent on criteria’s used in their evaluation. Single criteria evaluation of solar energy systems has shown its deficiency due to limited possibility to compare them with other potential options. In particular, present economic system is based on the econometric analysis with priority given to the optimum obtained by the economically justified optimization function. For this reason, it has become needed to introduce multi-criteria evaluation procedure in the assessment of solar energy system and its comparison with other potential options. This paper presents evaluation of the solar photovoltaic system and its comparison with other renewable energy system options for stand-alone application. In this evaluation following energy systems will be taking into a consideration: grid electric energy supply, wind energy system, gas turbine with cogeneration, small hydro energy system and solar photo-voltaic energy system. In the evaluation of these systems the multi-criteria evaluation procedure is used. The multi-criteria evaluation procedure will comprise a following criteria’s: economic, environmental, technological and social indicators. Each of indicators will be based on the sub-criteria which are defined in the paper. The sustainability index as the agglomeration function indicators will be used in the determination of the rating among the options under consideration. Special emphasize in evaluation is given to to the conditional priority of indicators leading to the investigation of the effect of the indicator priority to the finale rating among options.Copyright © 2004 by ASME