Optimal sizing of a hybrid photovoltaic/fuel cell grid-connected power system including hydrogen storage

The global energy demand is enormous, yet nonrenewable resources such as fossil fuels, and nuclear power are insufficient to satisfy it. Renewable energy will eventually be the better option. This study investigates the design and optimization of a hybrid photovoltaic / fuel cell (PV/FC) energy system with an H2 tank linked to the grid. The primary objective of this research is to design and size a PV/FC energy system with an H2 storage tank to supply the energy needs of a university ICT center that is connected to an inconsistent grid. HOMER's energy-balance algorithms were used to determine the best design architecture. Using mean solar radiation data (22 years) obtained for the University of Benin ICT Center, hourly simulations were performed to determine the optimum configuration in terms of size, cost, and performance of the energy system. Findings revealed that a hybrid PV/FC power system with a 400 kW solar array, a 250 kW FC, a 240 kW inverter, and a 150 kW electrolyzer with an H2 tank of 700 kg will reliably supplement the inconsistent grid with a high proportion (92%) of renewable resources at $0.1052/kWh. An energy cost reduction of approximately 88 percent and a return on investment of 200 percent with a present value of$98,251,110 could be obtained in less than 2 years over the traditional grid/diesel systems. Using an ideally sized PV/FC hybrid system will alleviate Nigeria's electrical challenges, impeding the country's economic growth. Furthermore, hybrid PV/FC power systems can reduce CO2 emissions, resulting in a more environmentally friendly and sustainable environment

Optimal sizing of a hybrid photovoltaic/fuel cell grid-connected power system including hydrogen storage

The global energy demand is enormous, yet nonrenewable resources such as fossil fuels, and nuclear power are insufficient to satisfy it. Renewable energy will eventually be the better option. This study investigates the design and optimization of a hybrid photovoltaic / fuel cell (PV/FC) energy system with an H2 tank linked to the grid. The primary objective of this research is to design and size a PV/FC energy system with an H2 storage tank to supply the energy needs of a university ICT center that is connected to an inconsistent grid. HOMER's energy-balance algorithms were used to determine the best design architecture. Using mean solar radiation data (22 years) obtained for the University of Benin ICT Center, hourly simulations were performed to determine the optimum configuration in terms of size, cost, and performance of the energy system. Findings revealed that a hybrid PV/FC power system with a 400 kW solar array, a 250 kW FC, a 240 kW inverter, and a 150 kW electrolyzer with an H2 tank of 700 kg will reliably supplement the inconsistent grid with a high proportion (92%) of renewable resources at $0.1052/kWh. An energy cost reduction of approximately 88 percent and a return on investment of 200 percent with a present value of$98,251,110 could be obtained in less than 2 years over the traditional grid/diesel systems. Using an ideally sized PV/FC hybrid system will alleviate Nigeria's electrical challenges, impeding the country's economic growth. Furthermore, hybrid PV/FC power systems can reduce CO2 emissions, resulting in a more environmentally friendly and sustainable environment

Follicular fluid content and oocyte quality: from single biochemical markers to metabolomics

The assessment of oocyte quality in human in vitro fertilization (IVF) is getting increasing attention from embryologists. Oocyte selection and the identification of the best oocytes, in fact, would help to limit embryo overproduction and to improve the results of oocyte cryostorage programs. Follicular fluid (FF) is easily available during oocyte pick-up and theorically represents an optimal source on non-invasive biochemical predictors of oocyte quality. Unfortunately, however, the studies aiming to find a good molecular predictor of oocyte quality in FF were not able to identify substances that could be used as reliable markers of oocyte competence to fertilization, embryo development and pregnancy. In the last years, a well definite trend toward passing from the research of single molecular markers to more complex techniques that study all metabolites of FF has been observed. The metabolomic approach is a powerful tool to study biochemical predictors of oocyte quality in FF, but its application in this area is still at the beginning. This review provides an overview of the current knowledge about the biochemical predictors of oocyte quality in FF, describing both the results coming from studies on single biochemical markers and those deriving from the most recent studies of metabolomic

Uterine perforation as a complication of surgical abortion causing small bowel obstruction: a review

OBJECTIVE: Small bowel obstruction after unrecognized or conservatively treated uterine perforation is extremely rare. It is a surgical emergency and the delay in diagnosis and treatment has deleterious consequences for the mother. The purpose of this study is to critically review the available literature and ascertain the level of evidence for the mechanisms, diagnosis and management of small bowel obstruction after uterine perforation due to surgical abortion. ----- METHODS: Systematic literature search was conducted in Pubmed (1946 to 2012) and Pubmedcentral (1900 to 2012) including all available English and French language fulltext articles. Three evaluators reviewed and selected all available case reports and case series. Search terms included small bowel obstruction, bowel obstruction, bowel incarceration, bowel entrapment, vaginal evisceration, uterine perforation, uterine rupture, and abortion. The exclusion criteria were (1) complex injuries where small bowel incarceration was present but with bleeding and/or bowel perforation as the leading symptomatology; (2) articles only numbering the patients without details on the topic. Analyses of incidence, risk factors, mechanisms of the disease, time of clinical presentation, diagnostic modalities, treatment, and maternal outcome were included. ----- RESULTS: Of the 73 articles screened 30 cases of small bowel obstruction were included in the review forming incidence, risk factors, and mechanisms of the disease, diagnosis, therapy, and maternal outcome. ----- CONCLUSIONS: A systematic review defined four mechanisms of small bowel obstruction after transvaginal instrumental uterine perforation with significant variations in clinical presentation and time of presentation. Duration of symptoms depend on the mechanism of small bowel obstruction. Vaginal evisceration is surgical emergency and treatment is mandatory without diagnostic workup. Survival rate during last century is 93 %. Multicentric trials and publication of all such cases are needed to determine algorithms for diagnosis and management of small bowel obstruction caused by instrumental uterine perforation

Environmental victims, access to justice and the sustainable development goals

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