The hallmark of the PhotoVoltaic (PV) electricity generation is its sustainability, while its main weakness is the low conversion efficiency. A drawback to which is added the PV cell sensitivity to temperature variations: the higher the cell operating temperature, the lower the efficiency. Considering that in-operation modules reach a conversion efficiency in the range of 10 to 15%, there is an urgent need to control their temperature to enhance the electricity generation. To this purpose, the authors developed a PV spraying cooling system able to drastically knockdown modules operating temperature. Using experimental measurements acquired through a dedicated test rig and after an in-depth literature review, the authors analyze the nozzles number, geometry, and position, as well as water and module’s temperature distribution, limestones formation, degradation of front glass properties, water consumption, and module power production with and without the cooling system. The experimental campaign shows that a cooling system equipped with three nozzles with a spraying angle of 90°, powered by water at 1.5 bar and managed in ON/OFF mode (30 s on to 180 s off), can improve the module’s efficiency from 11.18% to 13.27% thanks to a temperature reduction of up to 24 °C. Despite the improvement in electricity production (from 178.88 W to 212.31 W per single module), at the time of writing, the equipment and installation costs as well as the plant arrangement complexity make the investment not eligible for financing also in the case of a 1 MW floating PV facilities.

In the market of gas-fired devices, the share of condensing premixed boilers has strongly increased over the last years, since these devices will be the leading technology in the near future. Despite this, premixed burner design is currently mostly driven by trial and error methodology. Scientific research on burner concepts is active on theoretical, numerical, and experimental points of view, but there is a lack in appliance-oriented research. In the present study, the authors experimentally investigate the performance of cylindrical premixed burners coupled to a very common commercial premixed boiler setup, with special attention to the metal fiber application: the aim is to generate knowledge on applied premixed combustion, in order to assist future appliance-oriented burner design processes. A test protocol has been defined. Emission and flame stability characteristics have been identified for steel and fiber burners. The metal fiber contribution to the combustion behavior has been highlighted.

Nowadays, decarbonization of energy economy is a topical theme and several pathways are under discussion. Gaseous fuels will play a primary role during this transition, and the production of renewable or low carbon-impact gaseous fuels is necessary to deal with this challenge. Decarbonization will be sustained by an increasing share of renewables, which production intermittency can be critical for the energy system. Renewable hydrogen generation is a viable solution since this energy vector can be produced from electricity with a fast response and injected in the existing natural gas infrastructures, granting storage capacity and easy transport. Parallelly to the renewable-based energy production, fossil-based energy can be exploited with a low carbon impact, using methane from reservoirs to produce hydrogen capturing CO₂. The mentioned scenarios will lead to hydrogen enrichment of natural gas, which impact on the infrastructures is being actively studied. The effect on end-user devices, instead, is poorly analysed, but is fundamental to be assessed. This paper highlights the impact on the widely used premixed condensing boilers, which will be fired with hydrogen enriched natural gas in the near future, and the changes required to components.

The advancements on gas boiler technology run in parallel with the growth of renewable energy production. The renewable production will impact on the fuel gas quality, since the gas grid will face an increasing injection of alternative fuels (biogas, biomethane, hydrogen). Biogas allows producing energy with a lower CO2 impact; hydrogen production by electrolysis can mitigate the issues related to the mismatch between energy production by renewable and energy request. These technologies will contribute to achieve the renewable production targets, but the impact on whole fuel gas production-to-consumption chain must be evaluated. In the first part of this study, the Authors present the future scenario of the grid gas composition and the implications on gas fed appliances. Given that the widely used premixed burners are currently designed mainly by trial and error, a broader fuel gas quality range means an additional hitch on this design process. A better understanding and structuring of this process is helpful for future appliance-oriented developments. The Authors present an experimental activity on a premixed condensing boiler setup. A test protocol highlighting the burners' flexibility in terms of mixture composition is adopted and the system fuel flexibility is characterized around multiple reference conditions.