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MgO/H2O/Mg(OH)2 chemical heat storage of waste energy from industrial processes is a promising technology in view of a more efficient use and saving of primary energy sources. A new approach was used to develop a hybrid heat storage material made of magnesium hydroxide (Mg(OH)2) and exfoliated graphite (which is used to improve the heat transfer with its high thermal conductivity). Mg(OH)2 nanoplatelets were directly grown on graphite surface via a deposition–precipitation method to increase the compatibility between the two materials. The material thus obtained, named DP-MG, was experimentally tested to determine its heat storage and output capacities. An improvement of the material efficiency was obtained with a higher storage capacity at lower reaction temperature and a higher heat output rate.

Abstract This paper focuses on the impact of EUAs on the optimal policy of a competitive electricity producer. The effect of grandfathering is consistently shown to introduce significant distortions to the system. It is theoretically shown that there is a threshold value of carbon price so that, for prices above this, the EUA becomes an incentive for reduced production rather than a penalty for inefficient producers. These theoretical results are supported by the data of one producer from Italy and one from Germany. Furthermore, the empirical evidence concludes that the high level of free allowances may generate a shift in production from less to more polluting technologies.

This work has the purpose to analyze thermal performance of emergency shelters with the aim to develop different solutions which can improve the internal environmental conditions, in accordance to the parameters that describe thermo-hygrometric comfort, to the materials of which they are generally made of and to the climatic conditions under which they may be exposed. The object of the study was a tent equipped with a photovoltaic system produced by CHOSE (Center for Hybrid and Organic Solar Energy) at the University of Rome Tor Vergata. Through the use of the software IDA Indoor Climate and Energy 4.5, a simulation model was built based on experimental data collected from May 7 to May 15, 2013; model calibration was carried out comparing the simulation with the experimental data and the model was used for the formulation of different improvement solutions. The shelter model was analyzed in two different Italian climatic conditions using climatic data from Torino (winter) and Palermo (summer). The suggested optimization solutions were proven to be useful to improve the indoor climate and energy needs of the unit. The procedure can be applied to various climatic conditions and to different locations.

Abstract The contribution of wind power systems to the reduction of the impact of fossil fuels sources has increased more and more during the last decades leading to a greater attention to the estimation of the performances of renewable power plants. However, forecast methods of productivity of onshore/offshore wind farms still suffer, in terms of accuracy, the innate variability of the energy resources and the effect of components failures. This paper proposes a novel “hybrid” approach for the estimation of the energy conversion of onshore wind farms. The model combines the Jensen wake mathematical theory with a stochastic dependability model, a Fault Tree, to better forecast the energy production. A new key index was conceived to optimize the preventive maintenance of wind turbines. This model was tested on a real case study, a wind farm (25.5 MWp) located in the south of Italy. Results were promising because the model achieved a twofold objective to improve the accuracy of the energy conversion forecast and to provide a support decision system for the activities of maintenance planning.

Planktonic organisms are considered good indicators of environmental changes, even more sensitive than abiotic variables per se. In relatively recent years, the importance of pluriannual plankton series has become increasingly important, also for management purposes and in the process of bridging the gap between environmental science and management policy. Plankton studies in Lake Maggiore date back to middle 1900s, although a regular monitoring started in late seventies, in the framework of an agreement between Swiss and Italian Governments. The full long-term data series (1981-2011) entirely covers the lake's recovery, since full mesotrophy of mid-1970s, to present oligotrophy. Response of plankton communities to eutrophication reversal after lake restoration included a gradual increase in the number of phytoplankton taxonomic units and in cell density along with a decrease of average cell size. Changes in taxonomic composition, population density and mean body size were also tracked in the zooplankton. Data we obtained through these studies, however, pertaining to each single level of biological organization, do not allow per se for highlighting quantitative changes in trophic relationships and in ecosystem functioning driven by changes in trophy. Environmental changes, such as those attributable to eutrophication/oligotrophication processes, as well as to climate, are expected to affect not only taxonomic composition of planktonic assemblages, but also the trophic relationships and the ecosystem processes. Moreover, during the lake's oligotrophication the role of climatic constraints became increasingly important in controlling plankton dynamics, affecting phytoplankton nutrient supply, resource ratio, population phenology and the whole life cycles of the organisms involved. Our aim is to track the ecosystem response by analysing the phytoplankton-zooplankton relationship from a functional point of view, trying to find the key driver across different steps of the lake's trophic history, in the attempt to disentangle climate- from trophy-related responses of lake ecosystems.

This paper describes the needs an challenges in the sector of Life Cycle Assessment of Algae Biofuels

The lifetime and reliability of power transformers are primarily dependent on the hot-spot temperature in the windings, as temperature is the most important factor determining the insulation degradation rate. Key to removing the heat from the transformer is the radiator which must be carefully designed to keep the temperatures within limits under all operating conditions whilst minimizing the transformer size, weight and cost. This paper compares the analytical method used to predict the radiator performance with computational fluid dynamics (CFD) models in terms of heat dissipation. It is found that the analytical method and CFD models give similar results in the air natural (AN) cooling modes, whereas the analytical method overestimates the heat dissipation in the air forced (AF) cooling modes. Moreover, the thermal conduction effect in the radiator wall is investigated under different operating conditions and for different radiator sizes using the CFD models. The simulation results indicate that the radiator wall contributes to 6%-10% of the total heat dissipation under some circumstances and therefore should not be simply ignored in radiator models.

This paper investigates the energy distribution and the waste heat energy characteristics of a compression ignition engine for micro-cogeneration applications, at different engine speeds and loads. The experimental activity was carried out on a three-cylinder, 1028 cc, common-rail engine. Tests were performed with diesel fuel and a 20% v/v biodiesel blend (B20). The quantity and the quality of the waste heat energy were studied through energy and exergy analyses, respectively. Combustion characteristics were investigated by means of indicating data. Gaseous emissions were measured and particles were characterized in terms of number and size at exhaust. It was found out that the addition of 20% v/v of RME to diesel fuel does not affect significantly the brake fuel conversion efficiency and the energetic flows. On the other hand, biodiesel blend allows to reduce the combustion noise and the pollutants emissions in most of the operating conditions. A proper phasing of the injection strategy for the biodiesel blend could further reduce the exhaust emissions, mainly at high engine speeds. The results presented in this paper could be useful for the development of diesel engine based micro-cogeneration systems working at different engine speeds and loads.