• Energy Research
• 2021-2025close
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The most widely used process for hydrogen production is steam methane reforming. It can be carried out using a membrane reactor in which simultaneous hydrogen production and purification occur. Mathematical modeling of these reactors plays a key role in the selection of the design and operating parameters that yield high performance for the reactor. This review study discusses, synthesizes, and compares different mathematical modeling studies on the packed bed membrane reactors for hydrogen production from methane found in the literature. Different approaches used in these modeling studies for the hydrogen permeation steps, reaction kinetic expressions, phases involved (pseudo-homogeneous and heterogeneous), and spatial dimensions (one, two, and three dimensional) are given.

The launch traffic to Low Earth Orbit (LEO) is undergoing significant changes: instead of launching few, complex, large and expensive spacecraft, the trend is now towards the use of multitudes of small, less complex and lower-cost satellites. Large constellations, encompassing thousands of satellites in restricted regions of space, are emerging as important space assets. The intensifying commercial use of LEO and international debate regarding the stability of the space environment is a growing discussion among policy makers. Utilizing the SDM 5.0 evolutionary model developed by the Italian National Council of Research (CNR), the first step of this analysis is to estimate the growth of the space objects in LEO in the next decades. The analysis considers the space objects >10 cm, including active and defunct satellites, spent rockets bodies and fragments, along with varying future traffic, mitigation and remediation scenarios. Subsequently, the analysis focuses on the probability of collision with active satellites and on related mitigation and remediation scenarios. Based on this, the study employs a qualitative and preliminary approach to assess satellite operators' economic convenience of adopting measures that can mitigate the risk of collision by comparing their cost to the damage costs that may occur in case of collision. Finally, the study dedicate its concluding considerations to discuss if a free market setting can stimulate the formation of effective solutions to space debris challenges (namely, if it provides operators with the economic incentive to adopt or develop mitigation measures) or if public institutions' intervention is needed to finance mitigation strategies and, in particular, complex technologies development and adoption.

La transizione energetica e lo sviluppo sempre più capillare delle energie da fonti rinnovabili stanno suscitando un interesse sempre più crescente, favorendo la nascita di comunità per la produzione di energia e l'autoconsumo collettivo, al fine di ridurre drasticamente le emissioni e poter così raggiungere definitivamente l'obiettivo di decarbonizzazione prefissato per il 2050 dall'Unione Europea. Nel nostro Paese, le comunità energetiche potranno diventare il volano per le energie da fonti rinnovabili, permettendo ai cittadini di partecipare alla generazione, alla distribuzione, alla fornitura, al consumo, all'aggregazione ed allo stoccaggio dell'energia. Proprio attraverso una maggiore consapevolezza del fenomeno che si sta sviluppando, i cittadini possono associarsi ed effettuare scelte comuni per produrre localmente l'energia elettrica necessaria al proprio fabbisogno, anche condividendola, avendo così accesso a servizi di efficienza energetica. Queste nuove forme di mobilitazione collettiva, già note nei movimenti comunitari legati alla filiera alimentare, cominciano a diventare sempre più presenti nella costituzione delle comunità energetiche, con il fine ultimo, non solo di ridurre l'uso di fonti fossili ed emissioni, in favore di un sistema energetico basato sull'impiego di risorse energetiche rinnovabili, ma anche di poter produrre innovazione sociale in termini di empowerment delle persone, inclusività ed impatto di lunga durata, incoraggiando il cambiamento di pratiche sociali e valori collettivi; il mutamento tecnologico, quanto quello sociale, può essere soddisfatto solo da un forte coinvolgimento degli attori sociali.

This paper describes the results of an experimental campaign carried out on three urban buses fuelled by natural gas, aimed at measuring pollutant emissions and fuel consumption in real driving conditions. The buses, used for public transport in three Italian cities, were equipped with a Portable Emission Measurement System. Emission tests were performed over the routes on which the buses operate in their service, and cold start emissions were also investigated. The results showed that the differences in CO and NOx emissions can be attributed to the calibration of the fuel supply system. PM emissions were low and similar to those reported in the literature for other CNG buses, while CO2 and fuel consumption were affected by the driving cycle. Cold start strongly impacted CO and NOx emissions because of the effect of temperature on catalytic converter efficiency, with cold over-emissions strongly dependent on ambient and coolant temperatures at engine start.

In the recent years, some experimental forms of housing (cohousing and social housing) have developed in Italy, which also take on the features of real energy communities. These initiatives have been planned and implemented thanks to the active participation and investments of the people involved in the project. Their primary aim is to implement new form of shared housing, but by adopting renewable generation systems and sharing both energy production and consumption, they are contributing to foster the energy transition process. In this research, we studied the management of the energy resource and the social interactions among the cohousers. Moreover, we analysed the social impacts on the surrounding territory in order to know as they can widespread the clean energy technologies and social innovation processes. To do this, we compared two experiences of collaborative housing: the first one, active since some years in Northern Italy, is a bottom-up initiative set up by the voluntary action of some families and individuals. Its goal is to share common spaces and activities, but also to produce and use renewable energy with a view to economic and environmental sustainability. The second one is a social cohousing, established in Messina (Southern Italy) and implemented by the Fondazione di Comunità di Messina. The project involves people who live in socio-economic difficulties. Through the ESCO Solidarity & Energy, the Fondazione has designed and applied energy systems to allow the tenants to become prosumers and prosumagers.