• Energy Research
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Abstract This paper presents a non-stoichiometric equilibrium model for the simulation of biomass downdraft gasifiers. The chemical equilibrium is determined by minimizing the Gibbs free energy. Five elements characterize the biomass and 15 chemical species are considered in the syngas. The model calculates the lower heating value of the syngas and the relative abundances of gasification products. An advantage of this model is that it can easily calculate not only the concentrations of the main gasification products, but also the concentrations of minor product, especially the pollutant chemical species containing Nitrogen and Sulfur. To analyse the model behaviour, a sensitivity analysis on process parameters is presented. The model is validated by comparing its results with the results of simulation carried out with a stoichiometric model and with experimental data found in literature. Finally, the model is applied to the study of the gasification of forest waste.

AbstractAn analysis of Italy's National Energy Budget of in the last decades shows the important role of the civil sector and the impact of fossil fuels in air conditioning systems. The high consumption of fossil fuel is Likely due to the predominance of plants with conventional boilers in buildings. Based on the analysis of the Exergy flow this paper proposes the Cogeneration technology for Air conditioning systems with heat pumps to implement the Rational Use of Energy. The feasibility of a retrofit intervention on existing systems of a large size is shown, by the projection of a cogeneration plant for the buildings of the University of Cagliari currently equipped with fossil fuel plants.

Abstract The heating, ventilation and air conditioning plant of a historical valuable building in the centre of Vicenza (Italy) was retrofitted during 2007-2012 period. An underground water source electrical compression heat pump was installed with a monitoring and data logging system. In this paper the analysis of the performance data of the last three cooling seasons and the last two heating seasons (2014-2016) is developed. The analysis reveals that some critical aspects determined poor energy performance of the plant during the first operation period. Such issues and the technical solutions suggested by the Authors are presented in this work.

AbstractIn the last years, the number of installed biofuels power plants is increased in northern Italy, due to favorable legislation on renewable energy sources, posing the issue to assess the resulting environmental effects. The European legislation on emissions for renewable fuels power plants provides guidelines to be integrated in the local regulations; moreover, local authorities have to identify the critical power plants in terms of pollution and the key parameters to grant licenses for the future plants.The aim of this paper is to describe a methodology and the calculation routine developed to assess the environmental effects of biomass plants in terms of simple indexes. The used approach is based on the Cross-Media Effects described by a European Commission Reference Document. In particular, several indexes are introduced to cover the most relevant environmental effects, as: air toxicity, global warming, acidification, eutrophication and photochemical ozone creation. For every considered pollutant (such as NOx, CO, etc.) directly emitted by the power plant, specific factors have been identified, in order to calculate the contribution to the different environmental indexes. Finally, a numerical evaluation of different biomass power plants, installed in Emilia Romagna region, is provided, in order to assess their environmental cross-media potential and to compare such kind of power plants with large scale, fossil-fuelled power plants.

AbstractEnvironment respect makes both the Legislator ever more careful to define urgent emissions limits than each one responsible to find the best technological and behavioral solutions. The works includes the results of combustion simulations in a MGT burner. The purpose is to verify combustion performances of some between classic and renewable fuels, with a view to design choices. The approaches: a “Laminar Flamelet” model and, especially to verify simply kinetic influences, a partially premixed model.

Today 54 % of the world's population resides in urban areas and in 2050 the projections are for 66 %. Therefore, the issue of city sustainability becomes increasingly important. This paper analyzes city energy sustainability with consideration to the complex built environment, high population densities, anthropogenic activities, energy demands, environmental impacts, as well as limits on both space availability and renewable energy sources. The evaluation considers models of thermal energy consumption for both residential and non-residential buildings based on a GIS tool. The thermal energy-use models consider established statistical methods as well as the introduction of energy-dependent urban-scale variables.

AbstractThe energy sustainability, in the era of sources diversification [1], can be guaranteed by an energy resources utilization most correct, foreseeing no predominance of one source over the others in any area of the world but a proper energy mix, based on locally available resources and needs [2]-[4]. In this scenario, manageable with a smart grid system [5], [6], a virtuous use of RES must be visible, recognizable and quantifiable, in one word traceable [7]. The innovation of the traceability concept consists in the possibility of having information concerning the exact origin of the electricity used for a specific end use, in this case EV charging [8]. The traceability, in a context of increasingly sustainability [9], [10] and smartness city, is an important develop tool because only in this way it is possible to quantify the real emissions produced by EVs and to ensure the real foresight of grid load. This paper wants investigate the real ways to introduce this kind of real energy accounting, through the traceability.

Abstract Artificial lighting has a relevant impact on the electricity uses in non-residential buildings. The calculation method introduced in the relevant EN standards takes into account, only to some extent, the daylighting role on the lighting performances of buildings. An alternative method is under development for the Italian territory, which introduces a climate based approach to properly estimate the day light contribution. The method requires the implementation outdoor global and diffuse illuminance Typical Meteorogical Years (TMY), which calculated starting from solar irradiation data and luminous efficacy models. Different models can be used for this purpose, consequently these differences may lead to different estimates of daylight availability in buildings during the year. This paper explores the impact of different luminous efficacy models on the lighting energy uses in non-residential buildings. A typical office building is used for the study and calculations are carried out for three localities of the Italian territory. The outdoor luminous environment, the reference indoor visual task and the building daylight characteristics are taken into account. Results allow to compare the energy lighting performance of the building applying the different luminous efficacy models and, as a consequence, to select the most suitable model to be used in a climate based artificial lighting calculation method.