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Summary: In the modern world, only conventional energy resources cannot fulfil the growing energy demand. Electricity is a fundamental building block of a technological revolution. Today, most of the electricity demand is met by the burning of fossil fuels but at the cost of adverse environmental impact. In order to bridge the gap between electricity demand and supply, nonconventional and eco‐friendly means of energy generation are considered. Renewable energy systems (RESs) offer an adequate solution to mitigate the challenges originated due to greenhouse gasses (GHG). However, they have an unpredictable power generation with specific site requirements. Grid integration of RESs may lead to new challenges related to power quality, reliability, power system stability, harmonics, subsynchronous oscillations (SSOs), power quality, and reactive power compensation. The integration with energy storage systems (ESSs) can reduce these complexities that arise due to the intermittent nature of RESs. In this paper, a comprehensive review of renewable energy sources has been presented. Application of ESSs in RESs and their development phase has been discussed. Role of ESSs in increasing lifetime, efficiency, and energy density of power system having RESs has been reviewed. Moreover, different techniques to solve the critical issues like low efficiency, harmonics, and inertia reduction in photovoltaic (PV) systems have been presented. Unlike most of the available review papers, this article also investigates the impact of FACTS technology in RESs‐based power system using multitype flexible AC transmission system (FACTS) controllers. Three simulation models have been developed in MATLAB/Simulink. The results show that FACTS devices help to maintain the stability of RESs integrated power system. This review paper is believed to be of potential benefit for researchers from both the industry and academia to develop better understanding of challenges and solution techniques for REs‐based power systems and future research dimensions in this area. [ABSTRACT FROM AUTHOR]

Summary: Human activities are directly related to fossil fuel consumption and cause global warming and climate change effects by emitting greenhouse gas into the lower atmosphere. To reduce and adapt to such effects, renewable energy sources such as surface dams, including hydroelectric energy (HE) generation units, are gaining importance. In the current literature, HE potential calculations are based on formulations that are quite simple, clear and do not distinguish between different situations. In this paper, two classification methodologies are proposed for better assessment of HE production. The first one is based on the concept of the hypsographic curve to distinguish different drainage basin features into "Young," "Mature" and "Old." The second classification takes into account the newly defined energy index (EI) principle, which helps to classify the HE generation capability of drainage basins into "Very low," "Low," "Normal," "High" and "Very high." The application of the proposed methodology is presented for three drainage basins from the upstream sub‐basins of the Tigris River in Turkey. A comparison of the results shows that the proposed methodologies not only give numerical values but also sets linguistically rational and logical rules for the HE potential of a drainage basin. In the upstream basin of the Tigris River, the EI values vary between 0.705 and 0.122, corresponding to the "High" and "Low" categories, respectively. It is recommended that these two classification procedures be considered before the construction of any dam for HE production. [ABSTRACT FROM AUTHOR]

Summary: This paper is concerned with innovative approaches to renewable energy sources computation methodologies, which provide more refined results than the classical alternatives. Such refinements provide additional improvements especially for replacement of fossil energy usages that emit greenhouse gas (GHG) into the atmosphere leading to climate change impact. Current knowledge gap among each renewable energy source calculation is rather missing fundamentals of plausible, rational, and logical explanations for the interpretation of results. In the literature, there are rather complicated and mechanically applicable methodologies, which require input and output measurement data match with missing physical explanations. The view taken in this review paper is to concentrate on quite plausible, logical, rational, and effectively applicable innovative energy calculation methodologies with simplistic fundamentals. For this purpose, a set of renewable energy methodological approaches is revisited with their innovative structures concerning solar, wind, hydro, current, and geothermal energy resources. With the increase in the renewable energy utilizations to combat the undesirable impacts of global warming and climate change, there is a need for better models that will include physical environmental conditions and data properties in the probabilistic, statistical, stochastic, logical, and rational senses leading to refined and more reliable estimations with application examples in the text. Finally, new research directions are also recommended for more refined innovative energy system calculations. [ABSTRACT FROM AUTHOR]

SUMMARY Although the energy crisis has been slightly abated in the recent times, the possibility of a crisis caused by extremely high oil prices is still imminent. Simultaneously, the environmental crisis represented by climate change is further the major concern which requires an immediate solution. Hence, in this research, economical and environmental assessment of utilizing renewable energies in comparison with natural gas have been investigated which resulted to choose the best economically-environmentally alternative for power generation. Equivalent uniform annual value and scaling-weighting check list with experts' comments through analytical hierarchy process have been applied for economical and environmental assessment, respectively. Afterward, the results of normalized economical and environmental assessment have been coalesced to gain a combined economical-environmental perspective. As economical surveys, four scenarios have been considered. The results reveal that the best choices are conventional steam cycle, combined cycle, and biogas if power is sold to consumer (other technologies have negative net present value in this scenario), respectively, without considering the social costs and the emission reduction. If power is sold to government, biogas, conventional steam cycle, combined cycle, and wind are technological priorities. In case of considering social costs and emission reduction incomes, the best choices are biogas, combined cycle, and conventional steam cycle, respectively, if power is sold to consumers. If not, the priorities are biogas and wind. Furthermore, environmental surveys have indicated that wind is the most applicable environmentally friendly energy to produce electricity with negative impact magnitude (NIM) of 1.3 (out of 10). In addition, photovoltaic, biogas, and hydropower remain at the next levels with NIM of 1.6, 1.7, and 3.2 (out of 10), respectively. While conventional steam cycle has 6.2 of NIM. Eventually, the combination of economical and environmental evaluation reveals that wind farms and biogas plants with normalized weight of 3.10 (310%) and 2.34 (234%) are the best choices of electricity generation method, respectively. Moreover, the least applicable one is conventional steam cycle with normalized weight of 0.63 (63%). To sum it up, wind farms and biogas plants are about five and four times more economical-environmental beneficial than conventional steam cycle power generation. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]