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Utilizing electricity from renewable resources is very attractive to decrease the dependence on fossil fuels. As a result, hybrid power systems are gaining more attention. This paper focuses on the optimal design and dynamic simulation of renewable-based, hybrid standalone power systems. The designed system is able to meet the energy need of a building with 5 kW peak electricity demand. Both the technical and economic feasibility of the system was investigated under various climatic conditions of Turkey. Diesel fuel consumption, energy cost and annual CO2 emissions were estimated and compared with the diesel generator-only system. A parametric analysis was also conducted to understand the impact of the capacity of the PV array, wind turbine and the battery on the CO2 emissions and the levelized cost of energy. The system in each location was optimized based on the minimum energy cost and CO2 emissions. (C) 2020 Elsevier Ltd. All rights reserved.

A method for predicting the lake trophic status relying on wintertime monitoring data was developed. The technique is based on A. G. Volokhonskii’s approach, according to which the values of the minimum energy costs calculated for the virtual model of the process of involving mineral nutrients in phytoplankton cells are universal criteria of these nutrients’ availability to phytoplankton. Statistically significant one-parameter linear dependence between the average annual concentration of total phosphorus (Pt) and the values of minimum energy costs (Ep), which characterize mineral phosphorus levels in February, was detected. A classification of the trophic status of lakes ofKazakhstan depending on the values of the minimum energy costs of mineral phosphorus in February was developed.