• Energy Research
• other engineering and technologies close
• English close
• National Research Council close

A new concept of a system for Combined Heat and Power generation is presented. The concept is based on hybrid use of two renewable energy sources, direct solar (thermodynamic solar) and biomass (indirect solar energy). Biomass combustion is conducted using a fluidized bed combustor. A second source of energy, given by the direct irradiation of the bed with a concentrated solar radiation, is integrated in the same system, using the fluidized bed as solar receiver. A Stirling engine converts heat into mechanical power. A Scheffler type mirror is adopted to allow irradiation of the system in a fixed focal point. Advantages of the proposed solution are illustrated and some preliminary results on the performance of the system, obtained with a simple model, are presented. The principal improvements with respect to existing systems of similar size and primary energy source are illustrated. The most important are the enhanced heat transfer processes that are realized with the help of the fluidized bed, and the possibility of continuous cogeneration during the day. Different working conditions are considered to estimate the contribution given by the burning of fuel, in presence as well as in absence of sun irradiation (as during the night). The distribution of energy shares among the different flux contributes is reported versus the amount of biomass burned per unit time. The results clearly demonstrate the advantage of coupling, in the same system, two sources for heat generation, thus maintaining the option of producing electricity without the supply of biomass fuel.

The relationship between cities and energy consumption has been of great interest for the scientific community for over twenty years. Most of the energy consumption, indeed, occurs in cities because of the high concentration of human activities. Thus, cities are responsible for a big share of carbon dioxide emissions (CO2). However, the debate on this topic is still open, mainly because of the heterogeneity of published studies in the selection, definition and measurement of the urban features influencing energy consumption and CO2 emissions, as well as in the choice of the energy sectors to be considered, in the territorial scale of analysis, and in the geographical distribution of the sample. Therefore, the goal of this research is to systematize and compare the approach, methodology and results of the relevant literature on the relationship between cities and energy consumption over the last twenty years. Furthermore, this critical review identifies the knowledge gap between what is known and what is still under debate and, based on that, it proposes a conceptual framework that will help to outline a new direction for future research and support local policy makers in the definition of strategies and actions that can effectively reduce urban energy use and CO2 emissions. Tema. Journal of Land Use, Mobility and Environment, Vol 10, No 3 (2017): Methods, tools and best practices to increase the capacity of urban systems to adapt to natural and man-made changes

An accurate evaluation of solar energy production in power grids is a crucial aspect for the optimal exploitation of the available resources and for the effective integration of photovoltaic (PV) generators. This is especially advantageous in a smart grid context where a higher penetration of renewable energy sources is expected combined with distributed intelligence and information and communication technology (ICT) infrastructures. In this paper the nonlinear autoregressive network with exogenous input (NARX) is used to perform hourly solar radiation forecasting, according to a multi-step ahead approach. Temperature has been considered as the exogenous variable in the analysis. The NARX topology selection is supported by a combined use of two techniques: 1. a genetic algorithm (GA)-based optimization technique for the determination of the best weight set and 2. a method that determines the optimal network architecture by pruning it according to the Optimal Brain Surgeon (OBS) strategy. The considered variables are observed at hourly scale in a seven year dataset and the forecasting is done for several time horizons in the range from 8 to 24 hours-ahead. 29th European Photovoltaic Solar Energy Conference and Exhibition; 2574-2579

Biomass can play a key role in the development of distributed micro-generation appliances, allowing an easy and safe storage of energy in view of satisfying energy needs for the next future. As result of a recent project, called Megaris [1], a new micro CHP system has been proposed. Essentially, the system consists of a fluidized bed combustor with the heat transfer head of a Stirling engine in direct contact with the bed, where very low emissions can be achieved with a large variety of biomass sources, together with very high heat transfer coefficients towards the engine, raising its efficiency to competitive levels. To develop and optimize a configuration ready for introduction into the market, a reliable and fast model is required. In this work, a hybrid dynamic model is presented, consisting of a set of ordinary differential equations and of a Neural Network submodel introduced for those aspects that cannot be represented by lumped parameter models. The resulting model must correctly reproduce effects due to the fluidization regime that effectively establishes as working conditions are changed, both on heat transfer coefficients and on combustion efficiency. Results of the model are compared with experimental data collected on a prototype of the combustor equipped with a Stirling engine. The model is able to correctly reproduce the dynamic behavior of the system under different working conditions, with the accuracy required to perform design and optimization analysis. Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 724-731

In this work, thermocouple particle densitometry (TPD) has been demonstrated to be a valid tool for the analysis of combustion-formed carbon nanoparticles. The TPD methods has been successfully used to describe both particle volume fraction and the chemical evolution of carbonaceous nanoparticle in an ethylene/air premixed flame. Scanning mobility particle sizer (SMPS) and Raman spectroscopy have been used in comparison with the TPD analysis and to corroborate the TPD results. As a result, TPD has shown excellent agreement to the SMPS particle volume fraction measurements along the entire flame, starting from the very low values at the inception region. Furthermore, TPD has shown a clear evidence that the two classes of carbon nanoparticles, i.e. the two modes of the particle size distribution, strongly differentiate in terms of their graphitization degree based on the different values of emissivity of the material deposited on the thermocouple. While primary soot particle, i.e. those with diameter 10-20 nm, present emissivity of approximatively 1, thus acting as a black body, nucleated nanoparticles present emissivity values of about 0.5-0.6 indicating that they have a lower graphitization degree, i.e. higher content of organic carbon as compared the grown ones. Finally, Raman scattering, measured directly on the thermocouple previously coved by carbon nanoparticle, supported the TPD analysis. The possible use of TPD as valid, reliable and cost-effective combustion aerosol sensor in hot gas-stream is discussed.

This paper explores the feasibility of adopting ecological based planning in low-income residential development. It explicates that in developing countries efforts by housing authorities have been on housing provision irrespective of the environmental threats to sustainability. As these houses are built, future of urban ecology is under threat. The questions regarding this phenomenon are several: how do low-income populations perceive environmental issues of urban settlements? How capable and willing are the local authorities to embrace and apply ecological based planning in residential development? What are the facilitating instruments of ecological-based planning? What are the prospects of integrating ecological based planning to low-income residential development? What are the restraining factors towards embracement of ecological based planning and how best can they be harnessed towards future ecological cities? The case study of Hatcliffe residential area in Harare shows that there are many challenges to overcome uncoordinated planning approaches, ineffective policies and legislative frameworks, weak institutional settings, financial constraints, outdated planning standards and regulations, poverty, lack of environmental stewardship and lack of political will among others. The study findings call for robust environmental conservation strategies, strong environmental stewardship, responsive institutional and funding mechanism backed by realistic legislative frameworks and robust policy rectification. Tema. Journal of Land Use, Mobility and Environment, Vol 7, N° 1 (2014): Smart Cities Challenges: Smart Environment for Sustainable Resource Management

When the degradation growth of a unit depends only on its age, a widely accepted model to describe the degradation phenomenon is the non-homogeneous gamma process, which proved to be suitable to model such degradation phenomena as wear, fatigue, corrosion, crack growth, erosion, and consumption. In this paper, a Bayesian inferential procedure using the Markov Chain Monte Carlo technique is proposed for the non-homogeneous gamma process with power-law shape function. All the process parameters are left to be assessed, and prior information is formalized on some quantities having a "physical" meaning. Both vague and informative priors are provided. Point and interval estimation of the process parameters and of some functions thereof are developed, as well prediction on some observable quantities that are useful in defining the maintenance strategy is proposed. Finally, the proposed procedure is applied to a real dataset consisting of the sliding wear data of four metal alloy specimens.

Coating systems protect metal substrates from environmental corrosion attack. However, although having good performances, the presence of specific metal ions in their composition represents a potential source of environmental contamination. The necessity to conciliate corrosion protection with environmental impact is; thereby, primary. This work was designed to study the performance of low environmental impact conversion coatings (surface pre-treatment and high-solids epoxy primer), such as those free from hexavalent chromium (Cr VI), layered on different substrates of aluminium alloy [Al 7075 (T6) unclad and Al 2024 (T3) unclad] widely used in aerospace applications. Substrate surfaces were first treated by environmentally friendly Cr-free products. Successively, on pre-treated substrates, high-solids, chromate-free epoxy primer was applied. The capability to protect substrates from corrosion phenomena was evaluated following exposure of 4 groups of samples to in situ marine atmosphere at the Genoa Experimental Marine Station (G.E.M.S.) of CIV.R.-I,SMAR., located in the port of Genoa, for 8, 16, and 24 months and in accordance with UNI EN ISO 8565:1997 Standard. Accelerated degradation of conversion coating was also studied by electrochemical impedance spectroscopy. To characterize the coating systems, the interface metal substrate/conversion coating, sections from different samples were submitted to microscope techniques. The experimental results reported in this paper give useful information regarding the protective power against substrate corrosion of some Cr-free conversion coatings that have, as compared to traditional Cr VI containing products, a lower impact on workers' health and on the environment.