• Energy Research

World countries have set itself to reduce greenhouse gas emissions in the short / medium term, and Europe committed itself to reducing Green House Gas (GHG) emissions to 80-95% below 1990 levels by 2050. These policies are based on the development of non-fossil energy supply and electrification. In this context, the increasing of shares of electricity produced from renewable sources is an ineluctable necessity. In recent years, the production of renewable energy has increased considerably, but given the dependance of these sources from sun daily cycle and weather, there is a mismatch between production and demand. This arises some issues as balancing the electricity grid, and in particular the use of the energy surplus and compensation of energy lacks, as well as the need to strengthen the electricity grid. Among the various new solutions that are being evaluated, there are: the accumulation in batteries, the compressed air and hydrogen storage. These solutions appear to be the most suitable to associate with the water accumulation (pumped hydro). Concernig the hydrogen, recent research highlights that the efficiency hydrogen storage thechnologies have lower performance compared to advanced lead acid batteries on a DC to DC basis, but"...In contrast, according to the cost of Hydrogen storage is competitive with batteries and could be competitive with CAES and pumped hydro in locations that are not favorable for these technologies." [1] This means that, once the optimal efficiency rate is reached, the technologies concerning the production of hydrogen from renewable sources will be a viable and competitive solution for balancing electric grid. However hydrogen is not just a storage medium like batteries and conmpressed air, it is also a fuel with a number of possible applications. Consequently, what will be the impact on the energy and fuel markets? The production of hydrogen through electrolysis will certainly have an important economic impact not only in electricity and in the transport sectors, but will lead also to the creation of a new market and new supply chains that will change the physiognomy of the entire energy market.

As emphasised by the crisis caused by the COVID-19 pandemic, medical oxygen is an essential health commodity. The purpose of this study is the application of Renewable Energy Sources (RES)-based (photovoltaic-powered) water electrolysis plant for oxygen production in hospitals to self-produce the amount of oxygen they need, and - in particular - to define when this choice could be economically competitive with the current medical gas market. The proposed plant is able to produce oxygen and to store energy in hydrogen form at the same time, proposing a new approach in RES applications. Therefore, we calculated as a function of the hospital size (number of beds, up to 500) what should be the market price of oxygen above which the self-production of oxygen is economically profitable (assuming a break-event point of 15 years). Hydrogen is considered a by-product allowing to increase the system efficiency and supplying extra services. The results demonstrated that, assuming a selling price of 3 EUR/kg for the hydrogen (co)-produced by the plant, the on-site production of medical oxygen could be an interesting alternative compared to purchasing from the local gas resellers, if its market price is higher than 3-4 EUR/kg. Since this value is in line with current prices established for ex-factory oxygen by some national regulatory authorities (e.g., AIFA), we can conclude that the proposed RES-based electrolysis system is a green and economically feasible solution for oxygen production in hospitals, able also to increase hospital resilience against energy and oxygen shortage.

Reactants distribution over the active area plays a key role in the performance of PEM fuel cell. The flow path that is designed to uniformly distribute fuel and oxidant over the active area, has also to respect some geometrical constraints such as the active area shape. Serpentine layout has been proven as efficient design especially at cathode, due to the fluid motion established in the flow field. A convective flow through the gas diffusion layer, also called cross flow, has been demonstrated to be responsible for a better PEM fuel cell performance using serpentine flow channels. As highlighted in previous studies the intensity of the cross flow is affected by several parameters, such as the thickness and permeability of the gas diffusion layer and the serpentine path length, even though the correlation between the cross flow intensity and the fuel cell active area shape factor (MEA width/height) has never explored before. In this work a numerical and experimental study has been carried out to investigate the effect of the active area shape factor on the cross flow intensity and its effect on the fuel cell performance. Three-dimensional CFD simulation, including electrochemical aspects, has been performed for two different serpentine flow paths extending over the same active area but different in shape factor. The effect of reactants stoichiometry and humidification on the fuel cell performance have been also envisaged. Numerical computations has shown that cross over flow intensity is higher in the flow field with the lowest area shape factor. In terms of electrochemical performance, this flow field operates better at higher current density because the high intensity of cross flow enhances reactants concentration and improves water removal from the gas diffusion layer. Experimental tests have also been performed for a comparison with numerical results.

The operative conditions influence the performance of a polymer electrolyte fuel cell (PEFC). In particular, when a multi-cell (stack) instead of a single cell is investigated, a proper water management and flow stoichiometric ratio are essential for obtaining high electrical conversion efficiency. In this paper, a five cell air cooled PEM fuel cell stack was designed and realized, and systematic studies on the influence of the reactants humidification have been carried out to optimize the operative conditions. Polarization curves and time test at a fixed current have been conducted for various cathode (RHC) and anode (RHA) inlet humidity conditions. In particular, a small decay and low performance were obtained for RHA and RHCo70% and a considerable decay and low performance for RHA and RHC470%. A good compromise for water management, in terms of decay and performance, is obtained when a symmetrical RH of 70% was used, because in this case an optimal water balance was probably reached considering that high flow of gases was used. In fact, insufficient water content implies a lower ion conductivity of the membrane whereas excess of water yields to flooding of the electrodes and parasitic losses due to the presence of water in the gas channels. Consequently, these effects lead to a lowering of voltages during lifetime tests. In any case, the cathode RH has a stronger influence on the stack decay compared to the anode one. In the optimal selected conditions of RH a constant and stable power of about 55W (at 20 A) was obtained during the 15 h of operation.

Flexible carbon nanofiber (CNF)-based electrodes and CNF with a 20% of manganese oxide incorporated (Mn3O4/CNF) are prepared by using the electrospinning method for vanadium redox flow battery (VRFB) application. A blend consisting of manganese acetate (Mn(OAc)2) and polyacrilonitrile (PAN) is electrospun and successively subjected to different thermal treatments in which the growth of Mn3O4 particles and CNFs occurred together guaranteeing an appropriate electron conductivity for electrodes thus synthesized. Cyclic voltammetry (CV) measurements show an interesting electrocatalytic activity toward the [VO]2+/[VO2] + as well as the V2+/V3+ redox reactions for the Mn3O4/CNF electrospun sample. Charge-discharge tests, carried out at 80 mA cm2 , show a state of charge (SOC) and a depth of discharge (DoD) of 81% and 73%, respectively, for the cells assembled with Mn3O4/CNF electrodes. These data are indicative of a high vanadium active species utilization thanks to the better electrocatalytic activity at high current densities. Furthermore, the cell with Mn3O4/CNF shows EE values of about 81% (88% of VE and 92% of CE) vs. 70% (75% of VE and 93% of CE) with respect to a commercial carbon felt (CF) electrode used for comparison. These results are attributable to the higher oxygen species content as well as the improved electron conductivity due to the synergetic effect of the more graphitic carbon and to the structural defects within the Mn3O4 spinel structure.

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ETRERA_2020 is a project funded by the EU call FP7-INCO-R2I, and aimed at improving S&T and entrepreneurial relationships between EU Member States and the Neighboring Mediterranean Countries in the strategic field of renewable energy production, storage and distribution by actions targeted to bridging the existing gap between research and innovation. ETRERA_2020 will address its efforts on secure, clean and efficient energy societal challenge with a focus on: wind, photovoltaic, solar thermal, hydrogen and fuel cells, smart grids. The project is based on the creation of a research network involving primary actors across the research to innovation value chain consisting of 8 Research centres , 2 Intermediary organization providing innovation support services & technology transfer, 2 Business community & Entities managing industrial cluster and science park & incubator. The project foresees a set of ambitious objectives to be reached within its conclusion both by improving human resources & know how of NPC centers, both by increasing the networking opportunity, the public - private partnership, the accessibility to research facilities, and the project/partners visibility. The approach to the project and its preparation, management and implementation will be exposed.