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This work aims to assess the impacts of climate change on photovoltaic (PV) electricity in two Italian cities, with different latitudes and Köppen–Geiger climate classifications. This was undertaken using the recent EURO-CORDEX set of high-resolution climate projections and PV power generation models, implemented on TRNSYS software. Data for two variables (surface air temperature and solar radiation) were analysed over a long period from 1971 to 2100. For future periods, two of the Representative Concentration Pathway scenarios (RCP4.5 and RCP8.5) used in the Intergovernmental Panel on Climate Change Fifth Assessment Report were considered. In both RCP scenarios and both locations, it is estimated that the yearly PV energy produced in the future period will not undergo significant variations on average given that the rate of decrease is foreseen almost constant; instead, a slight reduction in the PV energy was detected in the past period. It can be concluded that the PV market in Italy will grow in the next years considering that the reduction in the foreseen PV purchase costs will be also supported by the slight positive effect of climate change on PV manufacturability. [ABSTRACT FROM AUTHOR]

Reversible solid oxide cell (rSOC) can flexibly switch between the electrolysis mode and the fuel cell mode for electrical energy storage and power generation. For practical application, sweeping gas is needed to bring in the reactants and take out the products timely. In this study, we use steam as anode sweeping gas in electrolysis to decrease the overpotential loss and collect pure O 2 , which is then used as the fuel cell cathode oxidant. The real fluctuating power generated from solar photovoltaic is used as the power supply, which allows rSOC to generate H 2 from 6:45 a.m. to 5:45 p.m. and produce electricity in the night. Compared with the conventional strategy, the proposed system can utilize more than 35% electricity in electrolysis, and its efficiency and total H 2 production can be increased by 8% and 50%, respectively. The total power generation and the power density are also increased by 290% and 160%, respectively. Overall, this new strategy results in a doubled round-trip voltage efficiency due to the much-decreased overpotential losses in the electrochemical processes. This study provides a guidance for the optimization of practical rSOC application with dynamic operating conditions. • 2D dynamic models for tubular SOEC and SOFC are developed. • Parametric studies on SOECs are conducted with fluctuating PV power supply. • H 2 O is used as sweeping gas in SOEC and pure O 2 is used as reactant in SOFC. • The production efficiency and rate of H 2 are increased by 8% and 50%, respectively. • Power generation and power density are increased by 2.9 and 1.6 times, respectively. [ABSTRACT FROM AUTHOR]

• Proposition of heat-up efficiency to evaluate start-up procedures energetically. • Thermal parameters for electrolysis systems with up to 1 MW el are presented. • Efficiency when only using heating is always lower than partial-load heat-up. • Introduction of a new dimensionless heat-up number for electrolyzers. • Dimensionless heat-up number enables general estimation of time constants. Dynamically-operated water electrolyzers enable the production of green hydrogen for cross-sector applications while simultaneously stabilizing power grids. In this study, the start-up phase of polymer electrolyte membrane (PEM) water electrolyzers is investigated in the context of intermittent renewable energy sources. During the start-up of the electrolysis system, the temperature increases, which directly influences hydrogen production efficiency. Experiments on a 100 kW el electrolyzer, combined with simulations of electrolyzers with up to 1 MW el , were used to analyze the start-up phase and assess its implications for operators and system designers. It is shown that part-load start-up at intermediate cell voltages of 1.80 V yields the highest efficiencies of 74.0 % LHV compared to heat-up using resistive electrical heating elements, which reaches maximum efficiencies of 60.9 % LHV. The results further indicate that large-scale electrolyzers with electrical heaters may serve as flexible sinks in electrical grids for durations of up to 15 min. [ABSTRACT FROM AUTHOR]