1,720,987 research outputs found
Response of electricity sector air pollution emissions to drought conditions in the western United States
No full textWater is needed for hydroelectric generation and to cool thermoelectric power plants. This dependence on water makes electricity generation vulnerable to droughts. Furthermore, because power sector CO2 emissions amount to approximately one third of total US emissions, droughts could influence the inter-annual variability of state- and national-scale emissions. However, the magnitude of drought-induced changes in power sector emissions is not well understood, especially in the context of climate mitigation policies. Using multivariate linear regressions, we find that droughts are positively correlated to increases in electricity generation from natural gas in California, Idaho, Oregon, and Washington; and from coal in Colorado, Montana, Oregon, Utah, Washington, and Wyoming. Using a statistical model, we estimate that this shift in generation sources led to total increases in regional emissions of 100 Mt of CO2, 45 kt of SO2, and 57 kt of NO x from 2001 to 2015, most of which originated in California, Oregon, Washington, and Wyoming. The CO2 emissions induced by droughts in California, Idaho, Oregon, and Washington amounted to 7%-12% of the total CO2 emissions from their respective power sectors, and the yearly rates were 8%-15% of their respective 2030 yearly targets outlined in the Clean Power Plan (CPP). Although there is uncertainty surrounding the CPP, its targets provide appropriate reference points for climate mitigation goals for the power sector. Given the global importance of hydroelectric and thermoelectric power, our results represent a critical step in quantifying the impact of drought on pollutant emissions from the power sector - and thus on mitigation targets - in other regions of the world.</p
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
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
SHEDDING LIGHT ON THE EQUITY VS EFFICIENCY DEBATE: Distributional Impacts of Dynamic Residential Electricity Pricing
No full text
Energy Storage and Renewable Generation: Perspectives from Economics, Technology, and Policy
No full textInterest in renewable energy has recently catapulted utility-scale electrical energy storage into
the energy policy limelight. Storage is often considered the panacea for providing more energy from
variable power sources, which can produce energy only with the wind or sun. Nonetheless,
valuations of storage generally find it the service not to be worth the investment. Given the
immense potential of energy storage to support the further integration of renewable energy and the
reliability of the U.S. electricity grid in general, this thesis makes a comprehensive evaluation of
storage from the three perspectives that matter most to a potential investor in energy storage: the
available economic value, the available technologies, and the market and regulatory environment in
which storage providers operate.
The thesis begins with a breakdown of the infrastructure, services, and markets that
comprise the power grid, and from this foundation builds a model of how storage may derive value
by bolstering the reliability of the grid, supporting the integration of renewable energy, and shifting
energy from times of low use to peak. It continues with a review of previous valuations of energy
storage, finding that nearly all of these studies neglect one or more value streams afforded by energy
storage, particularly its ability to reinforce the reliability of the energy system in the presence of
renewable energy. Using a counterfactual analysis, the thesis goes on to evaluate how the private and
social value of grid-scale storage changes under increasing renewable energy penetration, finding
these values to increase significantly as more variable energy is introduced to the grid, although not
so much that the installation of storage is guaranteed in the immediate future.
Other factors that affect the role of storage on the grid are the available technologies and
the relevant policies, both of which the thesis goes on to examine. It finds that several technologies,
able to span the range of applications that confer value on storage, are ready to be implemented on
the grid, but that in the absence of direct government incentives, very few have been. Although
incomplete valuation is a possible explanation for this phenomenon, an examination of the
experiences of energy storage with markets and the regulatory environment indicates that storage is
unable to realize a significant amount of its value. As a result, the thesis finds that the regulatory
environment must better align with the unique capabilities of energy storage in order to realize its
increasing value
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