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One of the world’s topical issues is the necessity of energy consumption reduction in order to conserve less and less natural resources and protect the environment. The article deals with the need to develop the waste energy recovery solutions that reduce energy consumption among the industrial consumers. In order to identify the sources with recoverable potential and establish energy recovery solutions, thermography of the hot air and hot gas exhaust circuits from industrial technological facilities were performed, followed by monitoring the operation parameters and measuring the energy consumption. The energy consumption reduction is analyzed by comparative interpretations of the hourly consumption, before and after applying the optimal recovery solution. The analysis of the results revealed that the waste energy recovery during the technological facilities operation has, besides the economic benefit, also other positive energetic effects, technical and not at least ecological ones.

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In this paper presents the mathematical modelling of the flowing river eutrophication process based on model kinetic equations QUAL2E and developed using Scilab-Xcos program. This can be seen graphically by the evolution over time of: algal mass, organic nitrogen, ammonia, nitrite nitrogen, nitrate nitrogen, organic phosphorus, soluble phosphorus, dissolved oxygen concentration and Biochemical oxygen demand for the oxidation of organic substances containing carbon in water of a river, in the case of discharge of a certain wastewater flow untreated, having a certain organic loading.

Exceeding intermitence and the stochastic character associated with most renewable energy sources in order to maintain the balance between generation and consumption require the most efficient energy storage methods. This balance is important to maintain the quality of the power supply by adjusting the frequency and voltage of the grid. Storage is the capture of the energy produced at a given time for later use. It is known that electricity cannot be stored directly unless it is stored in condenser batteries or in superconducting coils. Other methods of electricity storage presuppose the conversion of these into other forms of energy: mechanical storage, electrochemical storage. The optimization of RES operation and, implicitly, of the energy system implies the choice of a suitable conversion / storage system that must take into account a number of factors, such as: capacity and minimum storage time, loading and unloading conditions, minimum number of cycles download loading, power supply required by the storage system, system lifetime. It is not to be neglected the space required for the installation of the storage systems and their impact on the environment during their exploitation as well as during the post-use and recycling period. There are RES that contain natural storage systems (hydro-electric power plants and biomass and biogas generators). The article proposes an analysis of how to store electricity by approach a Pelton water-water-turbine hybrid system. The heat pump consumes electrical energy for action, producing a thermal effect. By integrating a system with Pelton water storage tank and turbine on the heat pump outlet circuit, the lost hydraulic energy can be recovered. The experimental hybrid system was made to develop HRES optimization models. Hybrid systems may exceed the limits of individual generators in terms of efficiency, economy, reliability and flexibility. An energy storage system can alleviate the problems associated with uncertainties and fluctuations from renewable sources. The large number of random variables and parameters in a hybrid energy system requires optimization to increase the efficiency of hybrid system components to achieve economic and technical benefits.

Abstract. Among the issues of the public services of economic interest, the water supply of urban and rural localities (areas where investment in this sector is limited) is of particular importance in maintaining social cohesion, raising the quality of life and ensuring sustainable development. The purpose of this analysis is to propose solutions for insuring and improving the water supply of isolated consumers in mountain rural areas, which is why a mountain tourist mountain hut has been chosen for this study. In this context, this paper addresses as a solution for the sustainable management of natural resources the use of rainwater. It is proposed to redesign the sanitary installation so that plumbing items that do not require drinking water can be fed through a separate installation. The proposed solutions are based on a comparative analysis of the microbiological parameters and the quality indicators between precipitation water and spring water with which the mountain hut is fed by an individual system. It is concluded that the recovery, storage and the use of the rainwater plays an important role in ensuring the supply of drinking water for the mountain cabin during periods when the water flow of the spring is low (in winter) and it contributes significantly to saving the freshwater resource in the area where the mountain hut is located.

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