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Renewable energy is an essential driver of the energy transition towards a more sustainable world. However, sustainability requires the coordination of the economic, environmental, and social dimensions, turning it into a complex objective. The aim of this study is to review the state of the art of the articles that analyze economic, environmental, and social metrics that can be used to evaluate the impact of renewable. In addition, this work also classifies metrics into two main approaches: macro-studies, corresponding to those that evaluate based on global and aggregated impacts, and micro-studies, corresponding to those that focus on regional and local impacts. A systematic literature review was used to identify and define these main metrics, based on common research databases. Seven metrics were found and described for the environmental impact, four for the economic impact and five for the social impact. The main finding revealed that micro-studies are more prevalent in comparison to macro-studies. Moreover, the systematic literature review allows achieving the objective and highlighting the proposed sustainability assessment framework as crucial for gauging and evaluating impact metrics across the economic, social, and environmental dimensions. The difficulty in isolating and measuring each metric may be attributed to the challenges involved in studying the corresponding impact, whether at the micro or macro level. More targeted studies can help in a more efficient energy transition.

Energy plants based on renewable energy sources can be combined according to the type of energy source (hydro, solar, wind with or without hydro storage). Currently, not enough attention has been paid to assessing the economic efficiency of combined power plants incorporating a hydraulic accumulator. When designing combined power plants, it becomes necessary to choose the composition of such plants and evaluate their economic efficiency. The purpose of this study is to justify the possibility of applying the present value method to select the composition of combined heat and power plants and assess their economic efficiency. The research used the following methods: review, synthesis of existing literature on the subject, system analysis, collection of data on different types of power plants, and calculation of their economic efficiency. A computer program has been compiled with Turbo Pascal 7.0 for the calculations. The calculations have shown that a cost-effective option is a combined power plant based on a wind power plant and a hydropower plant with a hydro accumulator.

Nowadays, microgrids (MGs) play a crucial role in modern power systems due to possibility of integrating renewable energies into the MG system. It is expected in near future collaborating microgrids as a community has a great affect in providing efficient energy for suppliers. Therefore, optimal operation of a MG, as a first step, is an important issue in this field. In this paper, by considering an integrated MG comprised of conventional generators, photovoltaic and wind a particle swarm optimization (PSO) is applied to minimize the cost function of the MG. Finally, the simulation results are discussed and analyzed to evaluate the system operation.

EU countries face two major challenges in the energy sector – the control of carbon emissions and the high dependence on imported primary energy sources. Both European Commission and national governments actively develop, update and upgrade strategies and plans for the energy sector. They aim to ensure the gradual reaching of consecutive targets for increasing the weight of Renewable Energies (RE) in the European primary energy mix. The selection of Renewable Energy investment projects in these sectors involves different groups of experts who have to consider the specifics of different countries, regions, and technologies. The Decision-making process becomes more complicated, as in addition to political goals it has to ensure the efficiency and competitiveness of European economies. Several conflicting objectives have to be balanced with complex social, economic, technological, and environmental factors. Our study explores the application of combined methods and evaluation techniques for improving the assessment and selection of prospective RE projects. We implement an innovative integration of the Analytical Hierarchy Process (AHP) for block criteria systematization combined with objective Shannon Entropy in the MOORA evaluation.

In the process of society, high-density livestock farms have developed rapidly to satisfy the increasing demand for meat products. Excessive wastewater from the livestock farms accordingly brought multiple pollution and deteriorate the environment, with the wastewater containing abundant chemical energy regarded as futility. Furthermore, the ingredients of wastewater varied from distinct livestock farms as a result of different animal feeding habits. Consequently, it is a necessity for specific wastewater treatment applied to a certain farm to control various pollution incidents while effectively recovering the potential chemical energy in wastewater. Microbial fuel cell, a device that converts chemical energy in the organic matter directly into electrical energy by a microorganism, is expected to be integrated with the existing wastewater treatment systems to make up for the shortcomings of existing technologies, improve the treatment efficiency and energy recovery rate. Therefore, it is a predictable trend for the microbial fuel cell to be combined with the traditional farm wastewater treatment system. This article demonstrates two traditional manure treatment methods: composting and biogas fermentation, followed by an evaluation of four advanced wastewater treatment technologies merged with microbial fuel cell. It is concluded that incorporating microbial fuel cells with separate wastewater treatment system will be a consequential sustainable development strategy in the future, with the purpose of fecal water treatment and energy recovery efficiently achieved.

The Cogeneration laboratory is a research facility in the University of Málaga (UMA) that allows for the behavioural study of a renewable energy installation combining solar resources and micro-CHP. Energy generation in the system is provided by a 3 kWp photovoltaic array, two solar thermal connectors and a Whispergen EU1 Stirling micro-CHP unit. Energy storage in the facility is provided by water tank and lithium-ion battery. This laboratory is managed through a programmable Mitsubishi PLC that permits the simulation of different thermal and electrical load profiles, as well as the mode of operation. The electrical energy management is controlled by the solar inverter. Environmental data, are measured using a top of the line weather station.The system’s real time status is logged through the programmable PLC. All this data is transferred and analysed in a purpose-built MATLAB-based software, where power and energy balances are conducted, efficiencies are calculated, and a CO2 emissions evaluation is studied.The CO2 emissions analysis is carried to evaluate the carbon dioxide emissions generated by the facility when the electrical and thermal demand are provided by the joint solar and micro-CHP system. These emissions come from the burning of natural gas in the micro-CHP Stirling engine, and the usage of electricity from the grid. With the current mode of operation, a reduction of up to 70% in CO2 emissions has been achieved, with an energy generation that exceeds the demand.

The present paper shows the background analysis to develop the optimization strategy of a neighborhood heating network sited in Padua, including it in a wider project of district renovation. The case study accounts several different end users: scholastic and offices buildings, a social housing residence and residential buildings. The analysis starts from a systematic assessment of the buildings, evaluating the need of refurbishment of the envelope and of the distribution system. Further analysis focuses on the optimization of the existing heat generation system, integrating three condensing boilers, with an air to water heat pump and a ground source heat pump, which work more efficiently during base-load periods. The management of the district heating network have been investigated using the dynamic simulation tool TRNSYS, the control strategy of the delivery temperature has been tested based on the outside temperature and verifying to satisfy comfort conditions inside the buildings. A sustainable solution is the recovery and drainage of rainwater, that can be reused for the toilets’ flushing. Therefore, the project solution identified aims at a more rational use of energy sources, which is the simplest and cheapest way to proceed on the decarbonization path that is a mid-term target for the Padua administration.

The increasing use of variable generation technologies (VGTs) in power systems, such as wind and photovoltaic generation, has introduced new challenges in the definition of capacity remuneration mechanisms for promoting system reliability. In this context, in this article we propose a novel framework for determining the capacity value of VGTs to contribute to the generation system adequacy, as well as a corresponding method for allocating capacity payments in hydrothermal power systems. We show that the capacity value of VGTs increases with the presence of water reservoirs, since VGTs help relieving hydropower plants from using scarce water resources during off-peak hours thus making more resources available to supply the demand during peak hours.

For an effective grid integration of a large share of intermittent renewable energy sources such as a photovoltaic and a wind power, the flexible operation of the centralized or decentralized thermal power plants are required as a control reserve of demandsupply balance (frequency control). It is cleared that the Solid Oxide Fuel Cell and Gas Turbine (SOFC/GT) with additional air compressor system offers high efficiency in the wide range load operation. The efficiencyload ratio curve of the Gas Turbine Combined Cycle (GTCC) and SOFC/GT with air compressor system are applied to the secondary control reserve (SCR) operation units, and the daily schedule of power units in the modelled power grid is calculated. Since the efficiency at low load is high in SOFC/GT with air compressor system, the total fuel cost of the modelled power grid diminishes in the case that the SOFC/GT with air compressor system is operated at low load as a load frequency control (LFC) unit for the SCR.

Many earlier studies have assessed the DH generation mix without taking explicitly into account future changes in the building stock and heat demand. The approach of this study consists of three steps that combine stock modeling, energy demand forecasting, and simulation of different energy technologies. First, a detailed residential building stock model for Herten is constructed by using remote sensing together with a typology for the German building stock. Second, a bottom-up simulation model is used which calculates the thermal energy demand based on energy-related investments in buildings in order to forecast the thermal demand up to 2050. Third, solar thermal fields in combination with large-scale heat pumps are sized as an alternative to the current coal-fired CHPs. We finally assess cost of heat and CO2 reduction for these units for two scenarios which differ with regard to the DH expansion. It can be concluded that up to 2030 and 2050 a substantial reduction in buildings heat demand due to the improved building insulation is expected. The falling heat demand in the DH substantially reduces the economic feasibility of new RES generation capacity. This reduction might be compensated by continuously connecting apartment buildings to the DH network until 2050.

The present study addresses the growing significance of renewable energies as a replacement for conventional gas and oil heating systems. Given the dynamic nature of these renewable energies, the integration of thermal simulations into building planning is becoming increasingly important. However, a significant portion of German standards remains static, especially the heating load calculation according to DIN EN 12831-1:2017-09. As the norm calculates the heating performance based on the day with the lowest temperatures, there is a risk that, among other things, the supply temperature will be incorrectly designed on milder days. The heating curve plays a crucial role, but it is usually adjusted only after the building's heating system is installed.