1,720,973 research outputs found
Techno-economics of renewable hydrogen export: A case study for Australia-Japan
No full textThe shift from fossil fuels to clean energy carriers, such as renewable H2, is imminent. Consequently, a global H2 market is taking shape, involving countries with limited or insufficient energy resources importing from renewable-rich countries. This study evaluates the techno-economics of renewable hydrogen (H2) export in a globally significant scenario in which Australia exports to Japan. To gain insight into the immediate, realisable future, the base year was selected as 2030, with a consequently small (in export terms) hydrogen production rate of 100 t/day landed capacity. Electricity was generated by photovoltaic arrays (PV) connected directly to proton exchange membrane (PEM) electrolyser plant, allowing for flexible gaseous hydrogen (GH2) production. To enhance the fidelity of the technoeconomic model, we incorporated rarely applied but impactful parameters, including dynamic efficiency and the overload capacity of PEM electrolysers. The GH2 produced was assumed to be converted into condensed forms suitable for export by sea: liquid hydrogen (LH2), and the chemical carriers liquid ammonia (LNH3), methanol (MeOH), methylcyclohexane (MCH). These were assumed to be reconverted to GH2 at the destination. LNH3 and MCH emerged as promising carriers for export, yielding the lowest landed levelised cost of hydrogen (LCOH). LH2 yielded the highest LCOH unless boiloff gas could be managed effectively and cheaply. A sensitivity analysis showed that a lower weighted average cost of capital (WACC) and scale-up can significantly reduce the landed LCOH. Increasing the production rate to 1000 t/day landed capacity very significantly lowered the landed LCOH, providing a strong incentive to scale up and optimise the entire supply chain as fast as possible.Full Tex
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Extracting adsorbate information from manometric uptake measurements of hydrogen at high pressure and ambient temperature
No full textTo calculate a gas sorption isotherm from measurements made using the manometric (Sieverts) technique requires accurate knowledge of the sample cell void volume, the volume able to be occupied by the free gas. For many combinations of material and morphology, this volume changes as the sample expands or compresses, swells, undergoes chemical change or adsorbs gas. For gas adsorption measurements on porous materials, the volume of the adsorbate is often accepted as the pore volume, and the adsorbate density changes as the material adsorbs. For materials exhibiting IUPAC type I isotherms, including many carbons, the uptake saturates at high pressures and additional information about the volume (adsorption space) and density of the adsorbate can be extracted at high pressure, provided adsorption has finished. For hydrogen, this typically requires cryogenic temperatures at pressures up to 10 MPa. In this work, hydrogen isotherms are conducted at pressures up to 200 MPa, in order to investigate the properties of the adsorbate at ambient temperatures. In addition, the manometric method gas uptake equations for absolute, excess and net isotherms are revisited and extrapolated to high pressure in order to extract information on the adsorbate volume and density, and enable the construction of the absolute isotherm.No Full Tex
Economics of renewable hydrogen production using wind and solar energy: A case study for Queensland, Australia
No full textThis study presents a technoeconomic analysis of renewables-based hydrogen production in Queensland, Australia under Optimistic, Reference and Pessimistic scenarios to address uncertainty in cost predictions. The goal of the work was to ascertain if the target fam-gate cost of AUD 3/kg (approx. USD 2/kg) could be reached. Economies of scale and the learning rate concept were factored into the economic model to account for the effect of scale-up and cost reductions as electrolyser manufacturing capacity grows. The model assumes that small-scale to large-scale wind turbine (WT)-based and photovoltaic (PV)-based power generation plants are directly coupled with an electrolyser array and utilises hourly generation data for the Gladstone hydrogen-hub region. Employing first a commonly used simplified approach, the electrolyser array was sized based on the maximum hourly power available for hydrogen production. The initial results indicated that scale-up is very beneficial: the levelised cost of green hydrogen (LCOH) could decrease by 49% from 3.1/kg when scaling PV-based plant from 10 MW to 1 GW, and for WT-based plant by 36% from 3.7/kg. Then, impacts on the LCOH of incorporating curtailment of ineffective peak power and electrolyser overload capacity were investigated and shown to be significant. Also significant was the beneficial effect of recognising that electrolyser efficiency depends on input power. The latter two factors have mostly been overlooked in the literature. Incorporating in the model the influence on the LCOH of real-world electrolyser operational characteristics overcomes a shortcoming of the simplified sizing method, namely that a large portion of electrolyser capacity is under-utilised, leading to unnecessarily high values of the LCOH. It was found that AUD 3/kg is achievable if the electrolyser array is properly sized, which should help to incentivise large-scale renewable hydrogen projects in Australia and elsewhere.Full Tex
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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