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Off-grid power systems represent one of the key solutions for rural electrification. Most of the analyses or tools already present in literature do not consider the final users' energy needs as the starting point of the process nor they consider the inherent uncertainties about loads and resources. Comprehensive stochastic procedures that look at the atypical features of rural contexts and include estimation errors into the design phase are strongly required. In this paper, we present Poli. NRG (POLItecnico di Milano - Network Robust desiGn): a novel software package for the robust design of off-grid electric power systems. Poli. NRG is composed of four blocks which separately face the different design phases: (i) the data inputs gathering block provides a methodology to collect field data as regards weather condition and load demand; (ii) the inputs processing block elaborates the inputs to obtain load and sources profiles over the entire lifetime of the plant; (iii) the system modelling and simulation block simulates different off-grid system configurations and evaluates the related techno-economic performances; (iv) the output formulation block finds the most robust design for the targeted context through specific optimization methods. After a comprehensive description of the software, we have applied it to size a PV + BESS microgrid system to supply power to a peri-urban area of Uganda. The results confirm that parameters' uncertainties deeply affect the design of the system and motivate the robust design approach proposed. Poli. NRG is devoted to map those uncertainties and provide information for decision makers. [ABSTRACT FROM AUTHOR]

Chongming’s current energy system is highly import-dependent and the distributed energy system with high renewable energy penetration should be taken into consideration. In this paper, a simulation model based on EnergyPLAN software with 2014 as the reference year is developed to represent Chongming’s present energy structure. Four future scenarios which propose different further energy constructions have been observed. Results show that reductions in primary energy consumption, electricity import, annual operating costs as well as CO 2 emissions are realizable when switching to an energy system with a high share of renewable sources combining natural gas CHP (Combined Heating and Power). After preliminary discussions, the feasibility of different renewable sources penetration are analyzed through calculating the excess electricity production (CEEP). The estimated optimal combination is generated when the PV fraction is 20% while wind energy fraction is 80%. Moreover, the analyses have taken into account that several flexible techniques are needed in order to balance supply and demand and to ensure the grid voltage and frequency stabilities. As a result, through the recommended three techniques, the excess production can be avoided as far as a renewable energy input of up to nearly 60%. [ABSTRACT FROM AUTHOR]

This paper seeks to analyse the differences between environmental impact assessment software tools by examining the results that they give when applied to a multi-megawatt wind turbine. Seven different life cycle impact assessment software tools are compared: CML 2001, Eco-indicator 99, Ecopoints 97, EDIP, EPS 2000, IMPACT2002 and TRACI. In Acidification and Eutrophication two groups are found: one includes the results provided by CML, Ecopoints 97, EDIP, EPS and TRACI and the other those of Eco-indicator 99 and Impact2002. In Abiotic Depletion all the results are similar except those of the EPS method, which gives negative figures. Likewise in Ozone Layer Depletion the results provided by Ecopoints 97 differ from the rest. In Human Toxicity and Ecotoxicity markedly different results are obtained by each of the LCIAs studied. In some categories major differences are found between the results provided by the 7 LCIAs examined. Which of the impact assessment software tools currently available in LCA software is chosen is therefore a critical issue. The results provided by the different software tools are not always similar, and this needs to be realised and taken into account when using the resulting data in decision-making processes. [ABSTRACT FROM AUTHOR]

Abstract: The present paper represents a part of a research study performed by authors in the field of energy management systems based on independent or connected to public supply network renewable energy systems. The main objective deals with the design and implementation of such management system so as to facilitate decision-making role in providing management and energy availability for consumers, both economically and in terms of safety power supplying. The requirements, the technical solutions, the electronic and software technologies are identified and followed by a prototype implementation to validate the proposed solution. The research results illustrate that by using such management information systems, the renewable energy sources in both individual and hybrid configurations, independent of the permanent or intermittent primary energy resource availability, can be effectively used. [Copyright &y& Elsevier]

Abstract: A high penetration of the Renewable Energy Sources (RES) can create stability, reliability and power quality problems in the main electrical grid due to their stochastic nature. The microgrid is one of the analysed solutions to solve this problem. In this context, the storage becomes necessary to better harness the energy generated by RES and to maintain the proper operation of the microgrid. This paper addresses the control of the bidirectional DC-DC converters used to interface a parallel connected Hybrid Energy Storage System (HESS) formed by a Vanadium Redox Battery (VRB) and a SuperCapacitor (SC) bank. The linear controllers have been widely used due to their simple design and implementation. However, their operation is limited to a certain operation range. The variability of the analysed system makes the use of a more robust controller necessary. In this work a PI based two-loop control system and a PI type sliding mode controller (SMC) are compared by means of simulations using the Matlab-Simulink software. Some rules are fixed to facilitate the design process of the SMC and the advantages of using a nonlinear controller are stressed. [Copyright &y& Elsevier]

Abstract: The work presented in this paper focuses on desalinating sea water system using a humidification–dehumidification process as it is supplied with water heated by geothermal energy as clean and renewable natural resources of energy. Computer simulation of the behavior under various working conditions of the desalination system was carried out to predict the variations of key output. Such variables include the ratio of sea water mass flow rate related to air mass flow rate, cooling water temperature difference across the condenser, geothermal source inlet temperatures to the heat exchanger and the amount of produced distilled water. To validate the computer program, a comparison between the experimental and theoretical results was conducted, and a good agreement had been obtained. The result showed that, the optimum value of the ratio between sea water mass flow rate to air mass flow rate was found to be in the range of 1.5 to 2.5. Improvement in the fresh water productivity at the optimum ratio of sea water mass flow rate to the air flow rate was observed by increasing both the geothermal source inlet temperature and the cooling water temperature difference across the condenser. [Copyright &y& Elsevier]

Abstract: The paper presents the aerodynamic design of a ventilation device suitable for remote open areas, such as desert terrains. The device is attached to the top of an enclosure roof and employs wind energy to create a partial vacuum in a specially designed duct to draw out the stale air from within the enclosure. The design is developed with the aid of fluid flow simulation software that is employed to predict the flow details corresponding to different geometric shapes so that an efficient shape may be found. The software is also employed to predict the performance of the adopted shape for different operating conditions and the results are presented in the form of characteristics curves and a correlation equation. Reliability of predictions is backed by results of experimental validation presented elsewhere, and by performing a detailed grid-dependence study, as well as a domain extent sensitivity analysis. [Copyright &y& Elsevier]