L. Hernández-Callejo, Sara Gallardo-Saavedra, Víctor Alonso-Gómez
Abstract Nowadays renewable energies are becoming more important in the generation of electricity. Fossil resources do not present a sustainable option for the future since they are non-renewable sources of energy that contribute to environmental pollution. Within the sources of renewable generation, photovoltaic energy is the most used, and this is due to a large number of solar resources existing throughout the planet. At present, the greatest advances in photovoltaic systems (regardless of the efficiency of different technologies) are focused on improved designs of photovoltaic systems, as well as optimal operation and maintenance. This work intends to make a review of the photovoltaic systems, where the design, operation and maintenance are the key points of these systems. Within the design, the critical components of the system and their own design are revised. Regarding the operation, it is reviewed the general operation and the operation of hybrid systems, as well as the power quality. Finally, in relation to the maintenance of PV systems, it has been studied their performance, thermography and electroluminescence, dirt, risks and failure modes.
Wind energy conversion systems have become a focal point in the research of renewable energy sources. This is in no small part due to the rapid advances in the size of wind generators as well as the development of power electronics and their applicability in wind energy extraction. This paper provides a comprehensive review of past and present converter topologies applicable to permanent magnet generators, induction generators, synchronous generators and doubly fed induction generators. The many different generator-converter combinations are compared on the basis of topology, cost, efficiency, power consumption and control complexity. The features of each generator-converter configuration are considered in the context of wind turbine systems
Abstract Hydrogen fuelling station is an infrastructure for the commercialisation of hydrogen energy utilising fuel cells, particularly, in the automotive sector. Hydrogen fuel produced by renewable sources such as the solar and wind energy can be an alternative fuel to depress the use of fuels based on fossil sources in the transport sector for sustainable clean energy strategy in future. By replacing the primary fuel with hydrogen fuel produced using renewable sources in road transport sector, environmental benefits can be achieved. In the present study, techno-economic analysis of hydrogen refuelling station powered by wind-photovoltaics (PV) hybrid power system to be installed in Izmir-Cesme, Turkey is performed. This analysis is carried out to a design of hydrogen refuelling station which is refuelling 25 fuel cell electric vehicles on a daily basis using hybrid optimisation model for electric renewable (HOMER) software. In this study, National Aeronautics and Space Administration (NASA) surface meteorology and solar energy database were used. Therefore, the average wind speed during the year was assessed to be 5.72 m/s and the annual average solar irradiation was used to be 5.08 kW h/m2/day for the considered site. According to optimisation results obtained for the proposed configuration, the levelised cost of hydrogen production was found to be US $7.526–7.866/kg in different system configurations. These results show that hydrogen refuelling station powered by renewable energy is economically appropriate for the considered site. It is expected that this study is the pre-feasibility study and obtained results encougare the hydrogen refuelling station to be established in Turkey by inventors or public institutions.
Sutthinee Keawmaungkom, Supatra Patrawoot, Panithi Wiroonpochit
et al.
Prevulcanization of natural rubber (NR) latex is a key process in producing diverse rubber products, as it governs their mechanical performance. Conventional sulfur prevulcanization is widely used owing to its simplicity and low cost, yet it poses environmental and health concerns due to zinc-based accelerators and sulfur compounds. This study compared five prevulcanization processes (sulfur-based; UV irradiation from fluorescent lamps, UV-Flu; UV from light emitting diodes, UV-LED; electron beam, EB; X-ray irradiation) using life cycle analysis (LCA) and life cycle cost analysis (LCCA). Laboratory experiments established the life cycle inventory (LCI) for processes that were then scaled up to industrial production scenarios. Measurements confirmed that all processes produced films that met ASTM requirements (Standard D3578–19). The LCA showed that EB irradiation minimized the environmental burdens because of short irradiation times and high throughput. X-ray prevulcanization resulted in the highest impact, driven by a high energy requirement and low productivity. UV-LED outperformed UV-Flu, reflecting higher efficiency of LED lamps and their longer life compared to fluorescent lights. The LCCA revealed sulfur-based process to be the most economic (US$ 1.48 kg−1), followed by UV-LED (US$ 4.38 kg−1) and the EB (US$ 10.56 kg−1). The X-ray process was prohibitively expensive (US$ 203.83 kg−1) and environmentally the most burdensome. Overall, the UV-LED and EB processes were most sustainable, especially if these technologies were developed further to reduce energy input and the hardware costs.
Renewable energy sources, Environmental engineering
Alessio Leins, Danaé Bregnard, Ilona Schäpan
et al.
Abstract One solution for reducing the scaling risk of lead (Pb)-containing phases consists of removing the aqueous Pb2+ ions from the brine by sorption before oversaturation at unwanted locations within the geothermal fluid loop. Hence, this study investigated the known capacity of fungal biomass to biosorb Pb2+ ions to remove Pb2+ from the brine. So far, biosorption studies have neither been done at high temperatures or salinity, nor under high pressure, three conditions that must be considered within geothermal power plants. Thus, the overall goal of this study was to assess the Pb2+ biosorption potential of dead biomass of the fungus Penicillium citrinum strain HEK1 under conditions mimicking those of natural highly saline geothermal fluids. This specific strain was isolated from geothermal brine circulating in a plant in which Pb2+ scaling occurs. To assess biosorption, dead biomass of P. citrinum was added to synthetic solutions containing 260 g/L NaCl, 1 g/L Pb, and (in half of the treatments) 60 mg/L acetic acid. These synthetic solutions, including the dead biomass, were then incubated at high pressure (8 bar), at different temperatures (25 °C, 60 °C, 98 °C), and for different time intervals (1 h, 2 h, 3 h). Results showed that the structure of the biomass was stable in such conditions, at all temperatures tested, but small amounts of organic compounds, with a wide variety of low molecular weight (< 350 Da to 10,000 Da) were released into the fluids from the biomass. In general, increased temperature resulted in an increase in dissolved organic carbon (DOC) concentration. The biosorption potential of P. citrinum HEK1 biomass was overall low (0.72% of total Pb2+). While it was not affected by changes in temperature, time of exposure or by the presence of organic acids within the fluids, salinity showed to be influential as biosorption increased to up to 19.22% of Pb2+ removal in non-saline conditions. Therefore, the high salinity of the fluids was the factor limiting biosorption to the highest extent, highlighting that working with highly saline geothermal fluids might be limiting for biosorption processes to happen efficiently.
The strong coupling $α_s$ is extracted with high precision through fits to lattice-QCD data for the static energy. Our theoretical framework is based on R-improving the three-loop fixed-order prediction for the static energy: we remove the $u=1/2$ renormalon and resum the associated large infrared logarithms. Combined with radius-dependent renormalization scales (the so-called profile functions), this procedure extends the range of validity of perturbation theory to distances as large as $\sim 0.5\,$fm. In addition, we resum large ultrasoft logarithms to N$^3$LL accuracy using renormalization-group evolution. Since the standard four-loop R-evolution treats N$^4$LL and higher-order contributions asymmetrically, we also incorporate this potential source of bias in our analysis. Our estimate of the perturbative uncertainty is obtained through a random scan over the parameters controlling the profile functions and the implementation of R-evolution. We analyze how the extracted value of $α_s$ depends on the shortest and longest distances included in the fit, on the details of the R-evolution procedure, on the fitting strategy itself, and on the accuracy of ultrasoft resummation. From our final analysis, and after evolution to the $Z$ pole, we obtain $α^{(n_f=5)}_s(m_Z)=0.1170\pm 0.0009$, a result fully compatible with the world average and with a comparable uncertainty.
In a groundbreaking advance for sustainable energy, a recent study unveils a transformative approach to hydrogen production, signaling a major shift in renewable energy. This study integrates one-dimensional covalent organic frameworks (COFs) with the innovative concept of harvesting atmospheric water, marking a significant stride in the quest for cleaner energy sources. It stands as the first successful integration of Atmospheric Water Harvesting (AWH) with photocatalysis, as well as the inaugural application of COFs in the photocatalytic evolution of hydrogen from water vapor. It envisions a future where our atmosphere becomes a vital, untapped reservoir for clean energy, merging cutting-edge science with a profound commitment to environmental sustainability. This breakthrough challenges conventional energy paradigms and opens up exciting possibilities for a world striving towards ecological balance and energy innovation.