Optimal integration of hydrogen-based energy storage systems in photovoltaic microgrids: a techno-economic assessment

The feasibility and cost-effectiveness of hydrogen-based microgrids in facilities, such as public buildings and small- and medium-sized enterprises, provided by photovoltaic (PV) plants and characterized by low electric demand during weekends, were investigated in this paper. Starting from the experience of the microgrid being built at the Renewable Energy Facility of Sardegna Ricerche (Italy), which, among various energy production and storage systems, includes a hydrogen storage system, a modeling of the hydrogen-based microgrid was developed. The model was used to analyze the expected performance of the microgrid considering different load profiles and equipment sizes. Finally, the microgrid cost-effectiveness was evaluated using a preliminary economic analysis. The results demonstrate that an effective design can be achieved with a PV system sized for an annual energy production 20% higher than the annual energy requested by the user and a hydrogen generator size 60% of the PV nominal power size. This configuration leads to a self-sufficiency rate of about 80% and, without public grants, a levelized cost of energy comparable with the cost of electricity in Italy can be achieved with a reduction of at least 25–40% of the current initial costs charged for the whole plant, depending on the load profile shape

Hydrogen storage integrated in off-grid power systems: a case study

This paper investigates the feasibility and benefits of integrating hydrogen storage systems into off-grid power systems. As a case study, a stand-alone microgrid located on a small island in southeastern Sardinia (Italy) and already equipped with a photovoltaic (PV) system coupled with batteries is chosen. To evaluate the integration benefits of the two storage systems (hydrogen and batteries) and the optimal sizing of the hydrogen storage section, a parametric analysis with a simulation model implemented in the MATLAB environment has been carried out. Results show that the optimal integration between the two storage systems is found by imposing a share of the batteries (18 kWh, 50% of the overall battery capacity) to exclusively supply the load demand (called battery energy buffer). In these conditions, an almost 100% self-sufficiency of the microgrid can be achieved by a hydrogen generator with the lowest size considered (2.4 kW), a hydrogen storage volume of 10 m3 and a fuel cell, mainly able to completely cover the night loads, of 1.5 kW. This sizing leads to a Levelized Cost of Electricity (LCOE) for the hydrogen section of about 10.5 /kWh

Nonylphenol induces proliferation of prostate epithelial cell line (PNT1a)

Nonylphenol (NP) belongs to Endocrine Disrupting Chemicals (EDCs) with xenoestrogenic activity, called xenoestrogens, abundantly present in the environment. NP is widely used as surfactants in industrial and agricultural applications and in plastic formulations. Its xenoestrogenic activity was demonstrated both in vitro and in vivo. However, there are only few studies on the NP effects on prostate cell lines. Estrogens play an important role in development and growth of the prostate and may cause some pathologies, including cancer. Since NP mimics endogenous estrogens, it could have a negative influence on prostate physiology. In this study we examined the effects of NP and 17β-estradiol (E2) on the proliferation of non tumorigenic prostate epithelial cell line (PNT1A) and their interaction with estrogen receptors. These effects were also studied in presence of selective estrogen receptor antagonist ICI182,780. We found that both NP and E2 stimulate PNT1A proliferation in a dose-dependent manner, but the NP effects were lower than E2. Immunofluorescence and western blot analyses revealed that both NP and E2 induce cytoplasm-nucleus translocation of ERα. The nuclear localization of ERα by E2 was already shown after 2h of treatment and only after 6h by NP. The inhibition of these effects by adding ICI182,780 was shown. Surprisingly, NP and E2 didn’t affect the localization of ERβ. These results suggest that NP stimulates PNT1A proliferation probably through the interaction with ERα that in turn is involved in the activation of some prostate cell cycle key regulators

Antioxidant Supplementation Hinders the Role of Exercise Training as a Natural Activator of SIRT1

Exercise training (ET) is a natural activator of silent mating type information regulation 2 homolog 1 (SIRT1), a stress-sensor able to increase the endogenous antioxidant system. SIRT1 activators include polyphenols and vitamins, the antioxidant properties of which are well-known. Antioxidant supplements are used to improve athletic performance. However, they might blunt ET-related benefits. Middle-distance runners (MDR) taking (MDR-S) or not taking antioxidant supplements (MDR-NoS) were compared with each other and with sedentary subjects (CTR) to evaluate the ET effects on SIRT1 levels and oxidative stress, and to investigate whether an exogenous source of antioxidants could interfere with such effects. Thirty-two MDR and 14 CTR were enrolled. MDR-S took 240 mg vitamin C and 15 mg vitamin E together with mineral salts. SIRT1 mRNA and activity were measured in PBMCs. Total oxidative status (TOS) and total antioxidant capacity (TEAC) were determined in plasma. MDR showed higher levels of SIRT1 mRNA (p = 0.0387) and activity (p = 0.0055) than did CTR. MDR-NoS also showed higher levels than did MDR-S without reaching statistical significance. SIRT1 activity was higher (p = 0.0012) in MDR-NoS (1909 ± 626) than in MDR-S (1276 ± 474). TOS did not differ among the groups, while MDR showed higher TEAC levels than did CTR (2866 ± 581 vs. 2082 ± 560, p = 0.0001) as did MDR-S (2784 ± 643) and MDR-NoS (2919 ± 551) (MDR-S vs. CTR, p = 0.0007 and MDR-NoS vs. CTR, p = 0.003). TEAC (β = 0.4488356, 95% CI 0.2074645 0.6902067; p < 0.0001) and the MDR-NoS group (β = 744.6433, 95% CI 169.9954 1319.291; p= 0.012) predicted SIRT1 activity levels. Antioxidant supplementation seems to hinder the role of ET as a natural activator of SIRT1

Italian multicenter study on infection hazards during dental practice: Control of environmental microbial contamination in public dental surgeries

Background. The present study assessed microbial contamination in Italian dental surgeries. Methods. An evaluation of water, air and surface microbial contamination in 102 dental units was carried out in eight Italian cities. Results. The findings showed water microbial contamination in all the dental surgeries; the proportion of water samples with microbial levels above those recommended decreased during working. With regard to Legionella spp., the proportion of positive samples was 33.3%. During work activity, the index of microbial air contamination (IMA) increased. The level of microbial accumulation on examined surfaces did not change over time. Conclusion. These findings confirm that some Italian dental surgeries show high biocontamination, as in other European Countries, which highlights the risk of occupational exposure and the need to apply effective measures to reduce microbial loads

Assessment of a hydrogen production, storage and utilization system in a demonstrative microgrid

This paper aims to investigate the expected performance of a hydrogen storage system integrated in a microgrid located in Sardinia (Italy). The microgrid includes several energy production and storage systems and serves a building with a number of offices and laboratories. The hydrogen is produced by two hydrogen generators during the weekends, stored in four stainless steel tanks and used in the following weekdays to partially cover the load demand through a fuel cell and to feed a methanation process. A proper modeling of the hydrogen-based microgrid has been developed and the expected performance in terms of annual hydrogen production and postponed use in the fuel cell have been analyzed. A preliminary economic analysis has been finally conducted for investigating the cost-effectiveness of integrating hydrogen production plants in facilities provided by photovoltaic plants and characterized by low electric demand during the weekends

Optimal generation scheduling for a hybrid stand-alone power system using renewable energy sources and hydrogen storage

This paper presents a novel energy management strategy (EMS) for hybrid stand-alone power generation systems powered by renewable energy sources and equipped with batteries and a hydrogen storage section. In particular, the proposed EMS defines the optimal generation scheduling of the two storage devices to minimize operating costs and maximize system efficiency. Since the achievement of the optimal EMS for stand-alone systems powered by renewable energy sources is strongly influenced by the uncertainties of solar and wind resources, a stochastic approach was adopted to deal with these uncertainties. The proposed EMS was used to evaluate the expected annual performance of a microgrid currently under construction at the Concentrating Solar and Hydrogen From Renewable Energy Sources Laboratory, in Sardinia (Italy). The study shows that the current hydrogen storage capacity of the microgrid is insufficient to meet the annual energy requirements, especially in winter months. To highlight the benefits of including weather forecasts and operating costs in the EMS, a comparative analysis with a simpler SOC-based EMS was carried out. The results of the comparative study demonstrate that the proposed EMS leads to a decrease of almost 5-10% in the annual operating costs and energy losses, especially for high values of the hydrogen storage capacity. In particular, for a hydrogen storage capacity of the studied microgrid 10 times higher than the planned one (55 Nm3), the adoption of the proposed EMS can achieve a decrease of about 10% in the annual operating costs and about 6% in the annual energy losses with respect to a conventional SOC-based EMS