1,721,368 research outputs found
A Global renewable energy roadmap: Comparing energy systems models with IRENA’s remap 2030 project
No full textIn 2014, the International Renewable Energy Agency (IRENA) published a global renewable energy roadmap–called REmap 2030–to double the share of renewables in the global energy mix by 2030 compared to 2010 (IRENA, A Renewable Energy Roadmap, 2014a). A REmap tool was developed to facilitate a transparent and open framework to aggregate the national renewable energy plans and/or scenarios of 26 countries. Unlike the energy systems models by IEA-ETSAP teams, however, the REmap tool does not account for trade–offs between renewable energy and energy efficiency activities, system planning issues like path dependency and investments in the grid infrastructure, competition for scarce resources– e.g. biomass–in the commodity prices, or dynamic cost developments as technologies get deployed over time. This chapter compares the REmap tool with the IEA–ETSAP models at two levels: the results and the insights. Based on the results comparison, it can be concluded that the REmap tool can be used as a way to explicitly engage national experts, to scope renewable energy options, and to compare results across countries. However, the ETSAP models provide detailed insights into the infrastructure requirements, competition between technologies and resources, and the role of energy efficiency needed for planning purposes. These insights are particularly relevant for countries with infrastructure constraints and/or ambitious renewable energy targets. As more and more countries are turning to renewables to secure their energy future, the REmap tool and the ETSAP models have complementary roles to play in engaging policy makers and national energy planners to advance renewables. © Springer-Verlag Berlin Heidelberg 2015
Tracking sectoral progress in the deep decarbonisation of energy systems in Europe
No full textDecarbonisation of energy systems requires deep structural change. The purpose of this research was to analyse the rates of change taking place in the energy systems of the European Union (EU), in the light of the EU's climate change mitigation objectives. Trends on indicators such as energy intensity and carbon intensity of energy were compared with decadal benchmarks derived from deep decarbonisation scenarios for the electricity, residential, transport, and industry sectors. The methodology applied provides a useful and informative approach to tracking decarbonisation of energy systems. The results show that the EU has made significant progress in decarbonising its energy systems. On a number of indicators assessed the results show that a significant acceleration from historical levels is required in order to reach the rates of change seen on the future benchmarks for deep decarbonisation. The methodology applied provides an example of how the research community and international organisations could complement the transparency mechanism developed by the Paris Agreement on climate change, to improve understanding of progress toward low-carbon energy systems. © 2017 Elsevier Lt
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Free surface boundary conditions for spilling waves: theoretical approach and numerical implementation
No full textThe recent advancement of numerical modeling has given valuable insights in the knowledge of wave transformation and interaction with coastal structures. In particular, the twophase flow formulation gives advantages towards a more accurate reproduction of the processes and a deeper understanding of the dynamics developing at wave breaking, where an aerated splashing regime is observed. However, such an approach is found to be computationally
expensive, especially in the case of large-scale analyses. Aim of the present paper is to describe a novel single-phase numerical model where the adopted free surface boundary conditions take into
account the multiphase mixing layer forming at surface deformation. Preliminary comparisons with available data on hydraulic jumps, stationary counterparts of bores, reveal good performances
of the model
Lithium isotope composition as tracer of crust/mantle interaction at subduction zones: a pilot study to understand the magma genesis of the Plio-Quaternary volcanic areas of Central Italy
No full textIn the framework of the FISR 2015-2016 “Centro di studio e monitoraggio dei rischi naturali dell’Italia
Centrale” project, we carried out a pilot study on the application of the lithium-isotope systematics to selected
igneous rocks, in order to shed new light on the nature of subduction components involved in the genesis of
magmas feeding the Roman Magmatic Province (Central Italy).
On the Earth, the two lithium isotopes, 6Li and 7Li, are susceptible to separation due to their relatively
large difference in mass (i.e., fractionation) as natural processes occur. These include mineral formation
(chemical precipitation), ion exchange (Li substitutes for Mg and Fe in octahedral sites in clay minerals,
with 6Li preferentially substituted over 7Li), and rock alteration. Among the available techniques, Thermal
Ionization Mass Spectrometry (TIMS) is inherently the most precise method for determination of the Li isotope
composition. In the last two decades, considerable progress has been made to minimize mass fractionation
during TIMS analysis. To date, no Li investigations have been performed on groundwater and volcanic
products from the Italian volcanoes to study water-rock interaction and/or magmatic processes, except for
Stromboli volcanics. This study acts as a driving factor towards the utilization of the Li-isotope systematics for
future studies, and can be considered as a first step towards the realization of a geochemical database including
Li isotopes, integrated with the available Sr, Nd, Pb, Hf, B and O isotopes on Italian Plio-Quaternary volcanic
rocks.
The final aim of this pilot study is to test the application of the Li-isotope systematics to shed new light
on the geochemical features of the subduction components involved in the genesis of magmas that fed the
activity of Colli Albani Volcanic District (Central Italy; e.g., Gaeta et al., 2016 and references therein). This
goal will be achieved by analyzing the Li isotope ratios of well-characterized (chemically and isotopically)
samples representative of eruptive products of the district, emplaced in the time window from 600ka to 40ka.
The activities carried out include: 1. Set up of the procedures to be adopted in clean chemistry laboratory
for extracting Li from natural samples; 2. chromatographic separation of Li in the NIST L-SVEC and USGS
BHVO-2 (batch #0759) standard samples, after acid dissolution; 3. Set up of the procedures for measuring Li
isotope ratios by TIMS.
Acknowledgements: This work benefited from financial support from FISR 2015-2016 “Centro di studio e
monitoraggio dei rischi naturali dell’Italia Centrale” project.
Gaeta, M., Freda, C., Marra, F., Arienzo, I., Gozzi, F., Jicha, B. & Di Rocco, T. (2016): Paleozoic metasomatism at
the origin of Mediterranean ultrapotassic magmas: Constraints from time-dependent geochemistry of Colli Albani
volcanic products (Central Italy). Lithos 244, 151-164
Clinopyroxene Growth and Dissolution Rates: High-Pressure Investigation on a Primitive Alkaline Basalt from the Campi Flegrei Volcanic District (South Italy)
No full textWith the aim to investigate the influence of time, temperature, water content and pressure on clinopyroxene growth and dissolution rate, we performed crystallization and dissolution experiments on a K-basaltic rock from Procida island (Campi Flegrei Volcanic District, south Italy). Crystallization experiments were performed at anhydrous and hydrous (1 ≤ H2O ≤ 4 wt.%) conditions, pressure of 0.8 GPa, temperature between 1030 °C and 1250 °C and dwell time between 0.25 and 9 hours. Crystallization experiments show that time is the factor that most affects the growth rate compared to temperature and water content. Clinopyroxene growth rate, indeed, varies from 10-7 to 10-8 cm/s and it reaches the maximum value in the shortest experiments (0.25 h) while it decreases increasing time (9 h). Comparing our high-pressure growth rates with the low-pressure ones available in literature related to clinopyroxene, it was possible to note that pressure does no affect the growth rate. Indeed, all the considered growth rates show similar values that vary from 10-5 to 10-9 cm/s regardless of pressure but as a function of time. Moreover, partition coefficients based on the crystal-liquid exchange demonstrate that the chemistry of minerals progressively approaches to equilibrium from the shortest to long-lasting experiments, putting forward the latter as representative of the ideal condition of crystallization in a deep magmatic reservoir. Short experiments, instead, could be representative of ascent mechanisms in disequilibrium conditions and quick times. Dissolution experiments, instead, were carried out at high pressure (0.8-2 GPa), superliquidus temperatures and different dwell times by using the seeding technique. Preliminary results show that clinopyroxene dissolution rate varies from 10-2 to 10-7 cm/s, highlighting an influence of temperature and time with respect to pressure
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