The use of nanofluids as a heat transfer fluid in solar energy conversion systems greatly improves photothermal conversion. In this study, numerical studies have been carried out using a volumetric solar collector to convert solar radiation into thermal energy. Because the collector is a translucent medium, 2D radiative heat transfer and energy equations are solved using ANSYS Fluent, which takes into account the absorption and scattering of nanoparticles. The results show that, ewhen hybrid nanofluids are used, the amount of heat obtained from solar radiation increases due to the temperature rise in the collector, hence improving the storage capacity of the collector.
Electric Vehicle (EV) penetration is rapidly increasing across the world and utilization of these in vehicle-to-grid (V2G) services can provide benefits to not just operation costs, but also resilience. To optimize the operation of EVs, as well as other local generation, demand and storage, the concept of microgrids has widely been used in the literature for smart control of local resources. During disruptive events such as microgrid islanding, EVs can act similarly to battery storage to minimize loss of critical loads. In this paper, day-ahead schedules are generated for EV operation in an urban multi-energy microgrid (MEMG) every 15 minutes for a 24-hour period. At each 15-minute timestep, individual EVs are updated based on a rolling EV dispatch strategy and real time data is fed back into the day-ahead schedule. After a predetermined time, an outage causes the microgrid to enter islanded mode. The combined and individual benefits of preventive and corrective control of EVs in increasing resilience is assessed, in addition to a comparison of the value of two novel rolling EV dispatch strategies. Results show that both control strategy and EV dispatch strategy can have a considerable effect on resilience enhancement provided by EVs.
This paper describes the design and optimization of the model-based predictive control (MPC) of a substation in the district heating system of the VUB campus. A properly controlled energy exchange improves the economy of the entire system while minimizing the pollutant emissions and fossil fuel consumption; the main goal of the European energy plan until 2030. The designed MPC modifies the flow rates in the substation, based on temperature evolutions and continuously provides an optimal return temperature in the network, while dispatching the desired amount of thermal power to the building. Compared to the installed proportional integral (PI) control, a reduction in substation return temperature of 10 °C can be obtained. The environmental and economic benefits of this reduced substation return temperature were assessed via a techno-economical model of the condensing boiler in the DHS, showing a 13% increase in overall efficiency, 11% of operational savings and a reduction of 5 ton in CO2 emissions, when compared with the experimental data of December 2020.
Based on an isentropic adiabatic compression of pure CO2 typical approaches using the isentropic relation are compared with properties calculated from a fundamental equation of state in form of the Helmholtz energy. The comparisons focus on the estimated energy consumption of the compression, the estimated end temperature, and a reasonable thermodynamic behavior.
This paper proposes and examines a highly integrated microgrid based on a reversible solid oxide cell, aimed at satisfying electrical and thermal loads of a 20-unit residential complex as well as the requests of electric and fuel cell vehicles. Such a system has been conceived as a profitable ready-made solution to be embedded into existing plants already equipped with renewable energy sources (i.e., wind farm and photovoltaic panels) by means of a reversible solid oxide cell and energy storage technologies. A dynamic programming-based routine has been suitably implemented as an algorithm for both electrical and thermal sides of the plant managing the power split indices. In addition, an external routine has been deployed to consider the economic aspects; in particular, attention has been paid to a levelized cost of energy analysis allowing for comparisons with current reliable energy generation technologies. The analyses involved parametric assessments of multiple reversible solid oxide cell sizes and economic discount rates while fixing the lifetime of the plant at 30 years. In accordance with the results of the optimal microgrid design, by exploiting 100% of the rSOC working time (shared by mode as 40% fuel cell and 60% electrolyzer) a simple payback period of 5.97 years has been achieved along with a levelized cost of energy index value in the 0.1 €/kWh-0.2 €/kWh range.
For the efficient exploitation of deep-water oil and gas resources, the microscopic mechanism of gas hydrate growth in the presence of waxy oil needs to be studied urgently. This work applied molecular dynamics (MD) simulations to explore the effect of wax molecules on methane hydrate growth. Based on the analysis of crystal growth, wax crystallization, and potential energy, the simulation results indicated that the addition of non-surface-active wax molecules inhibits hydrate growth, while the addition of surface-active wax molecules could extend the growth time of hydrate, thereby achieving more hydrate formation.
Current energy systems models do not generally provide a detailed analysis of environmental impacts. Even integrated assessment models (IAMs) that attempt to replicate the complex interactions between the economy, technosphere and biosphere at the global scale fail to consider impacts beyond the use of simplified relationships between parameters. This is troubling as energy technologies produce a range of environmental impacts within their life cycle beyond the carbon emissions that occur during the eventual energy production phase. Ignoring the nexus between energy systems, resource use and environmental impacts can also result in misleading information and misguided policy making. Life cycle assessment (LCA) methods provide far more detailed evaluations of processes within energy systems. Furthermore, combining LCA data with bio-economic metabolism approaches could enable the complex relationships between environmental impacts, material constraints and bio-economic functions to be assessed. Knowing that LCA outputs have previously been coupled with the well-established MuSIASEM approach to social metabolism, here we propose applying this synergy to the field of energy systems modelling. We introduce the ENBIOS module, a versatile methodology developed within the SENTINEL project that combines the bottom up, high resolution capabilities of LCA with the hierarchical multi-scale upscaling abilities of MuSIASEM for the analysis of energy systems at all scales. The module brings a more systemic methodology to the assessment of environmental impacts than previous approaches while offering a first attempt at quantifying the raw materials and circularity aspects that apply to energy systems. Recommended data inputs and possible indicators are also provided.
UNEP stresses the contribution of the individual consumption decisions to the global problems (i.e., loss of biodiversity, climate change, food and water security). These ecological problems are threatening the core of a sustainable development: the Food-Energy-Water-Nexus. Therefore, it will be analyzed how the different social groups of Germany contribute to the German consumption patterns. Seven social groups are selected and differentiated according to their income levels. For this analysis, the new German household expenditure survey (EVS) data sets of 2018 are used. To make the results comparable and independent of the household size of the social group, the equivalence income and expenditures of the social groups are determined. The equivalence data enables to measure the distribution of the household income and its expenditures for food, energy and water. Additionally, the empirical skewness is defined to determine the asymmetry of the income and consumption expenditures distribution. The new skewness equation is developed to analyze the distribution over the various household groups. Hence, it is possible to define the social asymmetry of the German society.
In response to climate change criticality, a number of policies have been implemented and imposed on all major sectors of energy production and consumption. European Green Deal policies and national climate and energy targets are leading to significant regulatory interventions that are having a major impact on the overall operations and decision-making of the companies and organizations. What do companies think about this and what is their social acceptance and attitude towards the newly imposed measures and energy efficiency? In this study, 711 companies are surveyed to determine their awareness, attitude and knowledge about climate policy and energy efficiency. The results show that company size influences overall understanding and attitudes towards climate and energy efficiency measures. The results show the most common energy efficiency measures implemented by companies that have contributed to significant energy savings. Media and emails are rated as the most common means of communication used by companies to obtain information on energy efficiency.
To increase the use efficiency of energy source production, the simulation modelling of hydrogen thermochemical Cu-Cl cycle integration into the existing gas-steam power plant is elaborated. The hydrogen produced is stored in tanks and consumed when the market price is favourable. The results of the modelling showed that the production and use of hydrogen, in combination with fuel cells, are expedient for the provision of tertiary services in the electricity system. In the event of a collapse of the electricity system, hydrogen and fuel cells could be used to produce electricity for the own use of the thermal power plant. The advantages of independent production of electricity are especially reflected in the start-up of a gas-steam power plant, as it is not possible to start a gas turbine without external electricity.