1,721,012 research outputs found
Renewable Energy Systems 2020
No full textIn the last few years, several states have experienced a significant growth of the global energy demand [...
Economic assessment of renewable energy systems integrating PhotoVoltaic panels, seawater desalination and water storage
No full textDesign and comparative techno-economic analysis of two solar polygeneration systems applied for electricity, cooling and fresh water production
No full textTwo solar polygeneration systems were investigated for electricity, cooling and fresh water production. In the first scenario (LFPS), the linear Fresnel (LF) solar field was used as thermal source of the Organic Rankine Cycle (ORC), absorption chiller (ACH) and multi-effect desalination (MED) unit. In the second scenario (PVPS), photovoltaic (PV) panels were considered as the electricity source to supply the electricity load that is required for lighting, electrical devices, compression chiller (CCH) and reverse osmosis (RO) units. A techno-economic comparison was made between two scenarios based on the land use factor (F), capacity utilization factor (CUF), payback period, levelized cost of electricity (LCE), levelized cost of cooling energy (LCC) and levelized cost of water (LCW). The calculations were conducted for four different locations in order to determine the effect of solar radiation level on the LCE, LCC and LCW of systems in both scenarios. The results showed that the LCE and LCW of PVPS is lower than that of LFPS and the LCC of LFPS is lower than that of PVPS. Also, the payback period of LFPS and PVPS systems are obtained as 13.97 years and 13.54 years, respectively, if no incentive is considered for the electricity sale
Geothermal Source Exploitation for Energy Saving and Environmental Energy Production
No full textMany European and some other developed countries have addressed the use of geothermal energy systems as a renewable source of energy worthy of investment and development. Geothermal energy is a non-intermittent and potentially inexhaustible source that can be used for energy saving and environmental energy production, as well as to provide heating and cooling to buildings, by increasing the energy efficiency of conventional systems. This editorial paper collects the most significant and recent studies, dealing with geothermal source exploitation, the possible role of geothermal systems in the building retrofit measures, the use of shallow geothermal sources, and specific aspects of systems that exploit geothermal energy
Optimization and dynamic analysis of a novel polygeneration system producing heat, cool and fresh water
No full textThermoeconomic analysis of energy saving measures for hospital facilities equipped with trigeneration plants
No full textHospital and health care facilities consume a huge amount of primary energy. The use of a trigeneration plant based on an internal combustion engine is a very common and reliable energy measure, widely adopted and studied, for reducing primary energy consumption and operating costs of this type of user. With the aim of further decreasing the primary energy consumption of hospital/health care facilities, additional retrofit energy measures are usually implemented. The aim of this work is to point out that if the retrofit of the hospital is carried out after the trigeneration plant installation, the possible energy and economic savings are dramatically limited by the trigeneration system. Unfortunately, this is a common mistake performed by system designers and facility managers. Conversely, energy saving measures must be performed before the installation of the trigeneration unit since they dramatically affect the selection of its capacity and operating strategy. Thus, the correct approach should consider the trigeneration unit installation only after a deep and carful energy retrofit of the hospital, allowing one to correctly select the capacity of the trigeneration unit. In order to prove this conclusion, a case study is performed for a real hospital in Italy. Here, a trigeneration unit has been installed and then additional energy saving measures are going to be implemented. This analysis is carried out by means of a dynamic simulation carried out using the TRNSYS software. In addition, each considered energy measure is validated against the measured data. The system was simulated in the present scenario where energy saving measures are implemented in the facility equipped with the trigeneration unit. In addition, the correct scenario was also simulated, calculating energy and economic performance parameters in the case in which such measures were implemented before the installation of the trigeneration unit. The comparison of the results proved that it is crucial to implement such energy saving measures before designing and installing the trigeneration unit
Smart grid energy district based on the integration of electric vehicles and combined heat and power generation
No full textThe issues dealing with climate change also caused by the private transport sector are attracting more and more attention in European Countries. This work aims to simultaneously address the issue related to the management of the energy demand of the private transport sector and building sector in the framework of the smart grid energy districts. The investigated smart grid is designed for meeting the energy demands of a district, including the energy demand for space heating and cooling, as well as the electric energy of a lot of buildings, occupied by people who only use electric vehicles. The system is equipped with a cogenerator, which is expected to operate according to the base-load operation strategy, constantly producing the rated power for whatever power demanded. Two charging strategies are analyzed and compared with the aim of detecting which strategy better exploits the power produced by the cogenerator. The performed dynamic simulations of the whole system are carried out by means of TRNSYS tool. TRNSYS allows one to use a detailed library of components which carefully model and simulate the devices included in the proposed system model. Suitable control strategies are also developed in order to improve the energy, environmental and economic performance of the smart grid. The results show that this layout allows one to considerably reduce the primary energy consumption and carbon dioxide emissions of the investigated district. As matter of fact, the proposed smart energy grid achieves a primary energy saving index of about 32%, with a payback period of about 6 years. These promising results suggest that the proposed smart energy grid may be useful for addressing the issue related with environmental impact of building sector and private transport sector
Heat metering for residential buildings: A novel approach through dynamic simulations for the calculation of energy and economic savings
No full textThis paper proposes a novel approach in order to accurately calculate the savings due to heat metering. The approach is based on a detailed dynamic simulation of building-plant systems. The building is geometrically modelled in Google Sketchup and linked to the TRNSYS environment, including an extremely detailed model for the simulation of building thermo-physical behavior. All the models are validated using the data provided by the occupants. The model allows one to evaluate the yearly energy demand, energy supplied by radiators, heat gains, etc. A specific case study is developed for a residential building located in Naples (South Italy). The developed model is used to calculate the building energy demand for 3 scenarios: centralized heating system not equipped with heat metering; centralized heating system with thermostatic valves and not equipped with heat metering; centralized heating system with thermostatic valves and equipped with heat metering. Results show that in case of centralized heating systems equipped with thermostatic valves and heat metering devices, thermal energy savings up to 64% can be reached mainly when the system operates for many hours per day, leading to discounted pay back periods lower than 4 years
Economic assessment of renewable energy systems integrating photovoltaic panels, seawater desalination and water storage
No full textThis paper presents a novel methodology for the management of the solar energy and seawater desalination, using water storage systems. The investigated plant includes photovoltaic panels, supplying a reverse osmosis unit for freshwater production. This novel methodology, based on the use of a water storage basin, allows one to avoid electric storage systems, determining a stable water production and maximizing the water self-consumption. The water storage basin allows one to obtain a significantly different trend of the freshwater availability with respect to the photovoltaic production, mainly occurring during the central hours of the day. The plant is dynamically simulated in TRNSYS environment. The proposed plant is assumed to operate in small Mediterranean islands, rich in solar energy and seawater availability, featured by a scarce freshwater availability and dramatically high freshwater costs. As main case study, Pantelleria Island (South Italy) is selected. The system energy performance is calculated implementing accurate models for all the system components. Special control strategies are implemented in order to maximize the system profitability, evaluated by considering both capital and operating costs. The developed system is extremely profitable: the achieved payback period is about 1.3 years, mainly due to high capital cost of freshwater in the reference scenario
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