1,721,001 research outputs found
Sistemi di accumulo elettrochimico per applicazioni stazionarie
No full textI sistemi di accumulo energetico possono svolgere un ruolo molto importante in quanto consentono di assorbire energia quando la potenza di generazione è in eccesso rispetto al carico, e di erogarla in situazioni opposte. Fra le varie tipologie di sistemi di accumulo energetico un ruolo speciale lo rivestono gli accumulatori elettrochimici nei quali, per l’appunto, l’energia è immagazzinata sotto forma di energia potenziale chimica e che si caratterizzano per la loro grande versatilità, rapidità di risposta, modularità.
L’articolo passa in rassegna le varie tecnologie di accumulo elettrochimico che sono usate o potenzialmente utilizzabili per applicazioni stazionarie, specificando i tipi di servizi di rete che possono svolgere, e vantaggi e svantaggi delle varie opzioni realizzative.
Verranno in particolare analizzate, in alcune delle varianti realizzative più utilizzate, batterie al piombo, al nickel-idruri metallici, al litio, al sodio-zolfo, al sodio-nickel-cloro (ZEBRA) nonché le batterie a flusso, le cosiddette “redox”
Implementation of the Modified Preisach Scalar Model in the Finite Difference – Time Domain Numerical Modelling
No full text
Analysis and Simulation of Rotating Magnetic Field Diffusion through a Parallelogram Hysteresis Model
No full textThis paper deals with the rotating electromagnetic
field diffusion into hysteretic materials. A simplified vector
formulation based on a parallelogram hysteresis model has been
investigated, in order to significantly reduce the computational
effort. Vector saturation and loss properties are discussed. Whole
simulation has been done by the use of a finite element time
domain algorithm
Energy, exergy and economic analysis of a novel geothermal energy system for wastewater and sludge treatment
Full text linkWastewater treatment is one of the most energy-consuming processes in the water sector, requiring both electric and thermal energy. In order to improve their sustainability, renewable energy sources can supply such energy demands in wastewater treatment plants, especially in small islands, where the lack of connections with mainland and environmental restrictions promote the use of unconventional fuels and technologies for energy production and waste treatment. For this reason, in this work, the use of geothermal energy is proposed for electric and thermal energy generation for wastewater and sludge treatment. An energy, exergy and economic analysis for the developed system is carried out. The study is carried out for a district wastewater treatment plant on the island of Ischia, in southern Italy, which presents diffused low-medium enthalpy geothermal sources, considered in this work to power an organic Rankine cycle system for electric energy production and to heat the desiccant flow for sludge drying. The proposed system reduces sludge to be disposed by around 70% and it covers 100% of the electrical energy demand of the wastewater treatment plant, with a production of 1.68 kWh per kg of processed sludge. Despite the high investment, the revenues deriving from the avoided sludge disposal and the electricity production, make the system convenient, with a simple payback of about 5 years and a saving of CO2 equivalent emissions equal to 628 tons/year. Therefore, the energy, exergy and economic analysis of the proposed system shows that the geothermal source is a viable and environmentally sustainable solution to produce electrical and thermal energy for wastewater and sludge treatment plants, especially in small islands or energy isolated systems, where electric energy supply and sewage sludge treatment are commonly critical challenges
A new example of circular economy: Waste vegetable oil for cogeneration in wastewater treatment plants
No full textWaste vegetable oil is generated from different sources, such as domestic, commercial and industrial activities, and it requires proper management. Due to the increase in the generation of waste vegetable oil, concern for its management has intensified. The most common management option for waste vegetable oil is the conversion into biodiesel, which improves the chemical-physical characteristics of raw waste vegetable oil for its use but is characterized by significant energy consumption and environmental impact. Therefore, straight waste vegetable oil as fuel, after mechanical pre-treatments and with suitable operational strategy, is suggested in the available literature. In this work, waste vegetable oil from the separate collection is proposed as a source to fuel a combined heat and power unit producing energy for wastewater and sludge treatment plants, which is high energy-demanding. The operation of the combined heat and power unit is analyzed considering data from an experimental campaign carried out to investigate the performance of internal combustion engines powered by waste vegetable oil. Such experimental data are used to carry out the feasibility analysis of a combined heat and power system for an actual wastewater treatment plant located in the Campania region, southern Italy. The system appears to be economically feasible with a simple payback around 3.44 years, a net present value higher than 19.0 M€ and an interest rate of return of 26.7%. Moreover, it produces 70.0% less equivalent carbon dioxide emissions, with respect to a similar system powered by fossil fuels. Therefore, waste vegetable oil as a locally available and renewable energy source may contribute to realize smart and resilient communities, since it improves securing domestic energy supply and waste valorization
Geothermal energy for wastewater and sludge treatment: An exergoeconomic analysis
No full textThe highest economic and environmental costs of wastewater treatment plants are related to waste disposal, which is mainly sludge disposal, and energy supply. Such challenges are even more critical in islands, where there are many environmental, landscape, and geographical constraints that make the use of conventional technologies difficult. For this reason, a geothermal energy system for wastewater and sludge treatment, and power production is proposed. Such a system is assessed through an exergoeconomic analysis, performed in Engineering Equation Solver environment, that allows determining the exergoeconomic costs of geo-fluid, electricity production, and sludge drying. The sensitivity analyses, carried out to assess the effect of several design parameters, have highlighted that the geothermal source temperature significantly affects the system operation and consequently the exergoeconomic costs, which range 77–95 c€/kWhex for sludge treatment and between 4.8 and 6.6c€/kWhex for electricity production. Finally, multivariate optimization has been carried out to find the conditions that minimize the exergoeconomic costs of the system. The total hourly exergoeconomic cost of the system products, namely sludge and electricity, is minimized when the geothermal source temperature is equal to 110 °C and the 58.91% of the desiccant flow is recycled. Overall, this study outlines that an exergy-based economic analysis is fundamental to assess the economic viability of innovative integrated solutions based on renewables
- …
