A new method to energy saving in a micro grid

Optimization of energy production systems is a relevant issue that must be considered in order to follow the fossil fuels consumption reduction policies and CO2 emission regulation. Increasing electricity production from renewable resources (e.g., photovoltaic systems and wind farms) is desirable but its unpredictability is a cause of problems for the main grid stability. A system with multiple energy sources represents an efficient solution, by realizing an interface among renewable energy sources, energy storage systems, and conventional power generators. Direct consequences of multi-energy systems are a wider energy flexibility and benefits for the electric grid, the purpose of this paper is to propose the best technology combination for electricity generation from a mix of renewable energy resources to satisfy the electrical needs. The paper identifies the optimal off-grid option and compares this with conventional grid extension, through the use of HOMER software. The solution obtained shows that a hybrid combination of renewable energy generators at an off-grid location can be a cost-effective alternative to grid extension and it is sustainable, techno-economically viable, and environmentally sound. The results show how this innovative energetic approach can provide a cost reduction in power supply and energy fees of 40% and 25%, respectively, and CO2 emission decrease attained around 18%. Furthermore, the multi-energy system taken as the case study has been optimized through the utilization of three different type of energy storage (Pb-Ac batteries, flywheels, and micro—Compressed Air Energy Storage (C.A.E.S.)

Energy study of a non-residential and historic building in transient conditions

The purpose of this manuscript is to analyse the interventions of energy retrofit of a non-residential and historic building, through dynamic simulation by the use of the TRNsys code. The study is made up of some steps: - the analysis of the building and utility data, including study of the installed equipment and analysis of energy bills; - the survey of the real operating conditions; - the selection and the evaluation of energy conservation measures; - the identification of interventions of energy retrofit; - TRNsys simulation of the effects of these interventions on the energy behaviour of the building. The present paper aims to present the results of the study, to discuss the expected energy behaviour of the building and to comment on the options for introducing energy conservation technique

Improving building energy efficiency: case study

The main purpose of this study was to conduct a study for improving energy efficiency of an important building in Rome, the Headquarters of the Italian State Monopoly. The study was conducted by comparing conventional analysis tools with innovative ones, in order to evaluate the possible solutions, both structural and plant, aimed at the use of renewable sources and at energy saving. After making a thermo graphic survey, the first and useful step for a good energy audit, conduct building energy was simulated, at first in steady state by the use of a software widely used at the professional level, then in transient state by the use of TRNSYS, a finite difference method software which is able to simulate more accurately conduct building energy. The next step was to propose possible redevelopment of a structural and energy plant that promotes the building energy rating higher, finding the right balance between the energetic and economic aspect. Among the interventions plant, two possible workarounds have been proposed and designed in detail: - installation of a photovoltaic system; - installation of a solar cooling system. Both solutions lead to a reduction of electricity consumption with a significant impact in economic and environmental term

Solar cooling: a case study

Throughout the years various methods for heat prevention and indoor temperatures control in the summer have been used. The alternative cooling strategies are based on various passive and low energy cooling technologies for protection of the buildings via design measures or special components to moderate the thermal gains, or to reject the excess heat to the ambient environment. All these techniques aim to reduce summer cooling loads and electricity demand for air conditioning. During the summer the demand for electricity increases because of the extensive use of heating ventilation air conditioning (HVAC) systems, which increase the peak electric load, causing major problems in the electric supply. The energy shortage is worse during ‘dry’ years because of the inability of the hydroelectric power stations to function and cover part of the peak load. The use of solar energy to drive cooling cycles for space conditioning of most buildings is an attractive concept, since the cooling load coincides generally with solar energy availability and therefore cooling requirements of a building are roughly in phase with the solar incidence. Solar cooling systems have the advantage of using absolutely harmless working fluids such as water, or solutions of certain salts. They are energy efficient and environmentally safe. The purpose of this paper is to describe a Solar Cooling System to be installed on the roof of a building in Rome, the headquarters of the State Monopoly. The medium size power plant is composed of the following components: − Solar Collectors; − Thermal Storage Tank; − Absorption Chiller; The plant design is based on a dynamic simulation in TRNSYS, a dynamic simulation tool used by engineers all over the world to make energy calculations in a transient state

A new tri-generation system: thermodynamical analysis of a micro compressed air energy storage

There is a growing interest in the electrical energy storage system, especially for matching intermittent sources of renewable energy with customers’ demand. Furthermore, it is possible, with these system, to level the absorption peak of the electric network (peak shaving) and the advantage of separating the production phase from the exertion phase (time shift). CAES (compressed air energy storage systems) are one of the most promising technologies of this field, because they are characterized by a high reliability, low environmental impact and a remarkable energy density. The main disadvantage of big systems is that they depend on geological formations which are necessary to the storage. The micro-CAES system, with a rigid storage vessel, guarantees a high portability of the system and a higher adaptability even with distributed or stand-alone energy productions. This article carries out a thermodynamical and energy analysis of the micro-CAES system, as a result of the mathematical model created in a Matlab/Simulink® environment. New ideas will be discussed, as the one concerning the quasi-isothermal compression/expansion, through the exertion of a biphasic mixture, that will increase the total system efficiency and enable a combined production of electric, thermal and refrigeration energies. The exergy analysis of the results provided by the simulation of the model reports that more than one third of the exergy input to the system is lost. This is something promising for the development of an experimental device

SYSTEMS FOR LIGHT DIFFUSION THROUGH TRANSPARENT MATERIALS: PERFORMANCE INDEXES RELATED TO THE CONTAINMENT OF LUMINANCE AND TO THE REMOVAL OF THE UV COMPONENT

This article relates the results of some research, the first phase of which has been presented in a CIE Convention in 2002. The subject of the research is the study of the materials usually employed for light diffusion, in particular the commercial and exhibition applications. In both cases, the role these materials have in the removal of the most damaging component of light, that is the power issued in UV fields, is pivotal. Altogether, the research involved different types of glass, micro-drilled metal plates, plastic materials and film

Bioclimatic design, assisted by numerical simulation in a transient state

The bioclimatic design aims to realize designing, localizative technological, plant-engineering choices, in order to have a housing model that satisfies comfort requisites through microclimate passive control and the control of the energy for heating plants. The study in this field is booming and, thanks to fast and effective calculation systems, the researchers can achieve reliable outcomes in reasonable times. Starting by a good thermal-energetic design and a bit of intuition, the bioclimatic design issue has been tackled scientifically and sistematically. So, we reached spe-cific and general conclusions useful to quantify and select the most used technics in this field. Our work doesn’t aim at a strict demonstration but at a study through which verify, understand and in-crease the knowledge of thermal-energetic phenomenon of building-environmental interaction. Many of the simulations in transient state have been made on matters we considered the most influential on the global behaviours of residential buildings. The matters on which we focused are: thermal cover (ther-mal insulation and inertia), glazed surfaces, screenings (static and mobile), in direct geothermal energy, vent (natural and artificial, diurnal and nocturnal). All this work has the aim to create the right balance between naatural cooling and heating during a while year, in order to guarantee thermal comfort to residents, thereby decreasing to a minimum the use of plants during the summer and the winter. The consequent designing-technical choices come from scrupulous interpretation of the outcomes, achieved by extrapolating from generic treatment the compatibility with the climatic conditions. In this per-spective, the authors, with the research, are using their knowledges to get innovative outcomes and integrate the research with empirical matters. residential buildings. The matters on which we focused are: thermal cover (ther-mal insulation and inertia), glazed surfaces, screenings (static and mobile), in direct geothermal energy, vent (natural and artificial, diurnal and nocturnal). All this work has the aim to create the right balance between naatural cooling and heating during a while year, in order to guarantee thermal comfort to residents, thereby decreasing to a minimum the use of plants during the summer and the winter. The consequent designing-technical choices come from scrupulous interpretation of the outcomes, achieved by extrapolating from generic treatment the compatibility with the climatic conditions. In this per-spective, the authors, with the research, are using their knowledges to get innovative outcomes and integrate the research with empirical matters

Caratterizzazione acustica del territorio urbano in presenza di insediamenti produttivi a ciclo continuo.

Tran

Acoustical comfort evaluation inside urban public buses

Hong Kong - Chin