Experimental investigation on CO2methanation process for solar energy storage compared to CO2-based methanol synthesis

The utilization of the captured CO2 as a carbon source for the production of energy storage media offers a technological solution for overcoming crucial issues in current energy systems. Solar energy production generally does not match with energy demand because of its intermittent and non-programmable nature, entailing the adoption of storage technologies. Hydrogen constitutes a chemical storage for renewable electricity if it is produced by water electrolysis and is also the key reactant for CO2 methanation (Sabatier reaction). The utilization of CO2 as a feedstock for producing methane contributes to alleviate global climate changes and sequestration related problems. The produced methane is a carbon neutral gas that fits into existing infrastructure and allows issues related to the aforementioned intermittency and non-programmability of solar energy to be overcome. In this paper, an experimental apparatus, composed of an electrolyzer and a tubular fixed bed reactor, is built and used to produce methane via Sabatier reaction. The objective of the experimental campaign is the evaluation of the process performance and a comparison with other CO2 valorization paths such as methanol production. The investigated pressure range was 2–20 bar, obtaining a methane volume fraction in outlet gaseous mixture of 64.75% at 8 bar and 97.24% at 20 bar, with conversion efficiencies of, respectively, 84.64% and 99.06%. The methanol and methane processes were compared on the basis of an energy parameter defined as the spent energy/stored energy. It is higher for the methanol process (0.45), with respect to the methane production process (0.41–0.43), which has a higher energy storage capability

An Innovative Configuration for CO2 Capture by High Temperature Fuel Cells

Many technological solutions have been proposed for CO 2 capture in the last few years. Most of them are characterized by high costs in terms of energy consumption and, consequently, higher fossil fuel use and higher economic costs. High temperature fuel cells are technological solutions currently developed for energy production with low environmental impact. In CIRIAF—University of Perugia labs, cylindrical geometry, small-sized molten carbonate fuel cell (MCFC) prototypes were built and tested with good energy production and lifetime performances. In the present work, an innovative application for MCFCs is proposed, and an innovative configuration for CO 2 capture/separation is investigated. The plant scheme is based on a reformer and a cylindrical MCFC. MCFCs are the most suitable solutions, because CO 2 is used in their operating cycle. An analysis in terms of energy consumption/kgCO 2 captured is made by coupling the proposed configuration with a gas turbine plant. The proposed configuration is characterized by a theoretical energy consumption of about 500 kJ/kgCO 2 , which is quite lower than actual sequestration technologies. An experimental campaign will be scheduled to verify the theoretical findings

UNA METODOLOGIA PER LA CONVERSIONE DEL LIVELLO EQUIVALENTE CONTINUO DI RUMORE NEL NUOVO INDICATORE EUROPEO LDEN

La normativa italiana relativa alla misura ed alla gestione del rumore ambientale, al-la luce della L.Q. n.447 del 1995 e dei relativi Decreti attuativi, definisce quale indicato-re per la valutazione del rumore ambientale il livello continuo equivalente di pressione sonora ponderata A (LAeq). In particolare, il D.P.C.M. 14 Novembre 1997 indica i valori limite di emissione e di immissione delle sorgenti sonore, relativi ai periodi di riferi-mento diurni e notturni, corrispondenti rispettivamente al periodo tra le ore 6 e le 22 ed a quello tra le ore 22 e le 6 [1]. La Direttiva 2002/49/CE del 25 giugno 2002 si è proposta di uniformare gli indica-tori dei singoli Paesi membri dell’Unione Europea: a tale scopo, è stato introdotto un nuovo indicatore del rumore ambientale, Lden, calcolato sulla base dei livelli di rumore misurati in tre periodi di riferimento: diurno, serale e notturno [2]. La raccomandazione della Commissione delle Comunità Europee 2003/613/CE del 6 agosto 2003, in base all’allegato I della Direttiva 2002/49/CE, ha successivamente da-to la possibilità ai singoli stati membri di modificare la durata del periodo serale [3]. Ri-sulta pertanto necessario, in previsione di un recepimento della Direttiva europea da parte della legge italiana, poter calcolare e/o stimare i valori del nuovo descrittore euro-peo Lden a partire dai livelli equivalenti di rumore relativi ai periodi di riferimento diur-no e notturno previsti dalla normativa vigente. Nella presente memoria, si propone una ipotesi di ripartizione della giornata nei pe-riodi di riferimento diurno, serale e notturno e una metodologia per la determinazione del descrittore acustico Lden, a partire dal LAeq relativo al periodo diurno e notturno e dalla distribuzione statistica dei livelli misurati durante tali periodi. La metodologia proposta è stata infine applicata ai risultati di una vasta indagine sperimentale che ha consentito di verificarne l’efficacia

Experimental Investigation on the Effect of Phase Change Materials on Compressed Air Expansion in CAES Plants

The integration of renewable energy in the electrical grid is challenging due to the intermittent and non-programmable generated electric power and to the transmission of peak power levels. Several energy storage technologies have been studied to find a solution to these issues. In particular, compressed air energy storage (CAES) plants work by pumping and storing air into a vessel or in an underground cavern; then when energy is needed, the pressurized air is expanded in an expansion turbine. Several CAES configurations have been proposed: diabatic, adiabatic and isothermal. The isothermal process seems to be the most promising to improve the overall efficiency. It differs from conventional CAES approaches as it employs near-isothermal compression and expansion. Currently, there are no commercial isothermal CAES implementations worldwide, but several methods are under investigation. In this paper, the use of phase change materials (PCM) for isothermal air expansion is discussed. Air expansion tests in presence of PCM were carried out in a high-pressure vessel in order to analyze the effect of PCM on the process. Results show that in presence of PCM near isothermal expansion conditions occur and therefore they affect positively the value of the obtainable expansion work

Experimental analysis of the CO

Nowadays natural gas hydrates represent a promising opportunity for counteracting several crucial issues of the 21th century. They are a valid answer to the continuously increasing energy demand, moved by the global population growth; moreover, considering their conformation and the possibility of using them for carbon dioxide permanently storage, gas hydrates may become a carbon neutral energy source, where for each methane molecule recovered, another carbon dioxide molecule is entrapped in solid form. Considering that the combustion of one methane molecule for energy production leads to the formation of one CO2 molecule, the hydrates exploitation can be considered a clean process in terms of impact on the climate change. This work shows how the presence of sodium chloride affects the CO2/CH4 replacement process into a gas hydrates reservoir. Replacement experimental results carried out in pure demineralised water were compared with the same values performed in a mixture of water and salt, having a concentration of 37 g/l. Some parameters of interest were discussed, such us methane hydrates formed before the replacement process, total amount of hydrates (composed by both species) reached at the end of the whole process, CO2 moles that formed hydrate, quantity of hydrate present before the replacement process which were actually involved in the CO2/CH4 exchange and carbon dioxide amount which led to the formation of new hydrates structures

Seizing the digital identity and payments opportunity : national and EU experiences

This contribution was delivered on 5 May 2022 on the occasion of the hybrid 2022 edition of EUI State of the Union on ‘A Europe fit for the next generation?'EU Member States have adopted several initiatives to establish a legal and technical framework for digital identity. The European Commission has facilitated this development by offering guidance and promoting interoperable solutions through frameworks such as eIDAS and solutions developed within the European Interoperability Framework. At the same time, two years of COVID-19 pandemic have led at once to an acceleration of digital identity projects, and mounting concerns that widespread data collection and availability can lead to the risk of privacy violations, citizen profiling and mass surveillance. This session will explore the opportunities and challenges of emerging digital identity and digital payments, including the privacy, security concerns as well as the outstanding opportunities for inclusive growth, resilient and sustainable solutions for the society of the future. The discussion will also cover emerging attempts to develop joint European solutions for digital identity, including the recent joint declaration between the governments of Finland and Germany to support the progress of the proposed regulation on European digital identity, and to accelerate the development of joint European solutions based on digital identity

Thermal Analysis of an Industrial Furnace

Industries, which are mainly responsible for high energy consumption, need to invest in research projects in order to develop new managing systems for rational energy use, and to tackle the devastating effects of climate change caused by human behavior. The study described in this paper concerns the forging industry, where the production processes generally start with the heating of steel in furnaces, and continue with other processes, such as heat treatments and different forms of machining. One of the most critical operations, in terms of energy loss, is the opening of the furnace doors for insertion and extraction operations. During this time, the temperature of the furnaces decreases by hundreds of degrees in a few minutes. Because the dispersed heat needs to be supplied again through the combustion of fuel, increasing the consumption of energy and the pollutant emissions, the evaluation of the amount of lost energy is crucial for the development of systems which can contain this loss. To perform this study, CFD simulation software was used. Results show that when the door opens, because of temperature and pressure differences between the furnace and the ambient air, turbulence is created. Results also show that the amount of energy lost for an opening of 10 min for radiation, convection and conduction is equal to 5606 MJ where convection is the main contributor, with 5020 MJ. The model created, after being validated, has been applied to perform other simulations, in order to improve the energy performance of the furnace. Results show that reducing the opening time of the door saves energy and limits pollutant emissions

Experimental Analysis of the Effect of Geometry and Façade Materials on Urban District’s Equivalent Albedo

Urban Heat Island (UHI) is influenced by urban form, geometry, and the properties of surfaces. Retroreflective (RR) materials have been proposed as a countermeasure to UHI, thanks to their optical property of reflecting most of the incident solar energy back towards the same direction. In this paper, the effect of RR materials on urban districts was investigated. They were applied on building façades of urban districts with different urban forms and orientations. To this aim, an experimental model resembling urban districts with different geometries was built and RR materials on vertical surfaces were tested and compared to conventional construction materials with similar global reflectance. The trend of the instantaneous albedo was monitored during the day and a new parameter called “equivalent albedo” was used to demonstrate the effectiveness of the RR materials. The comparative analysis shows that the RR façades lead to an increase of the equivalent albedo for all of the investigated urban patterns. For a block pattern, the equivalent albedo increase is equal to 3%, while for canyon patterns it is equal to 7%. Results of energy evaluations show that the energy savings obtainable with the use of RR materials is comparable to the values of anthropogenic heat emissions in residential areas

Clathrate Hydrates for Thermal Energy Storage in Buildings: Overview of Proper Hydrate-Forming Compounds

Increasing energy costs are at the origin of the great progress in the field of phase change materials (PCMs). The present work aims at studying the application of clathrate hydrates as PCMs in buildings. Clathrate hydrates are crystalline structures in which guest molecules are enclosed in the crystal lattice of water molecules. Clathrate hydrates can form also at ambient pressure and present a high latent heat, and for this reason, they are good candidates for being used as PCMs. The parameter that makes a PCM suitable to be used in buildings is, first of all, a melting temperature at about 25 °C. The paper provides an overview of groups of clathrate hydrates, whose physical and chemical characteristics could meet the requirements needed for their application in buildings. Simulations with a dynamic building simulation tool are carried out to evaluate the performance of clathrate hydrates in enhancing thermal comfort through the moderation of summer temperature swings and, therefore, in reducing energy consumption. Simulations suggest that clathrate hydrates have a potential in terms of improvement of indoor thermal comfort and a reduction of energy consumption for cooling. Cooling effects of 0.5 °C and reduced overheating hours of up to 1.1% are predicted