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  1. Article: Is it always windy somewhere? Occurrence of low-wind-power events over large areas

    Handschy, Mark A / Jay Apt / Stephen Rose

    Renewable energy. 2017 Feb., v. 101

    2017  

    Abstract: The incidence of widespread low-wind conditions is important to the reliability and economics of electric grids with large amounts of wind power. In order to investigate a future in which wind plants are geographically widespread but interconnected, we ... ...

    Abstract The incidence of widespread low-wind conditions is important to the reliability and economics of electric grids with large amounts of wind power. In order to investigate a future in which wind plants are geographically widespread but interconnected, we examine how frequently low generation levels occur for wind power aggregated from distant, weakly-correlated wind generators. We simulate the wind power using anemometer data from nine tall-tower sites spanning the contiguous United States. The number of low-power hours per year declines exponentially with the number of sites being aggregated. Hours with power levels below 5% of total capacity, for example, drop by a factor of about 60, from 2140 h/y for the median single site to 36 h/y for the generation aggregated from all nine sites; the standard deviation drops by a factor of 3. The systematic dependence of generation-level probability distribution “tails” on both number and power threshold is well described by the theory of Large Deviations. Combining this theory for tail behavior with the normal distribution for behavior near the mean allows us to estimate, without the use of any adjustable parameters, the entire generation duration curve as a function of the number of essentially independent sites in the array.
    Keywords economics ; geographical distribution ; normal distribution ; wind ; wind power ; wind turbines ; United States
    Language English
    Dates of publication 2017-02
    Size p. 1124-1130.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2001449-1
    ISSN 0960-1481
    ISSN 0960-1481
    DOI 10.1016/j.renene.2016.10.004
    Database NAL-Catalogue (AGRICOLA)

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  2. Book ; Online: Is it always windy somewhere? Occurrence of low-wind-power events over large areas

    Handschy, Mark A. / Rose, Stephen / Apt, Jay

    2016  

    Abstract: The incidence of widespread low-wind conditions is important to the reliability and economics of electric grids with large amounts of wind power. In order to investigate a future in which wind plants are geographically widespread but interconnected, we ... ...

    Abstract The incidence of widespread low-wind conditions is important to the reliability and economics of electric grids with large amounts of wind power. In order to investigate a future in which wind plants are geographically widespread but interconnected, we examine how frequently low generation levels occur for wind power aggregated from distant, weakly-correlated wind generators. We simulate the wind power using anemometer data from nine tall-tower sites spanning the contiguous United States. We find that the number of low-power hours per year declines exponentially with the number of sites being aggregated. Hours with power levels below 5% of total capacity, for example, drop by a factor of about 60, from 2140 h/y for the median single site to 36 h/y for the generation aggregated from all nine sites; the standard deviations drops by a factor of 3. The systematic dependence of generation-level probability distribution "tails" on both number and power threshold is well described by the theory of Large Deviations. Combining this theory for tail behavior with the normal distribution for behavior near the mean allows us to estimate, without the use of any adjustable parameters, the entire generation duration curve as a function of the number of essentially independent sites in the array.

    Comment: 15 pages, 11 figures
    Keywords Physics - Atmospheric and Oceanic Physics
    Subject code 551
    Publishing date 2016-07-22
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Fast beam steering with a ferroelectric-liquid-crystal optical phased array.

    Engström, David / O'Callaghan, Michael J / Walker, Chris / Handschy, Mark A

    Applied optics

    2009  Volume 48, Issue 9, Page(s) 1721–1726

    Abstract: We demonstrate fast, efficient beam steering using a single 1x32 analog ferroelectric liquid crystal (FLC) spatial light modulator. A high-tilt FLC material with 82 degrees optic-axis switching provides, in a reflective-mode device with a passive quarter- ...

    Abstract We demonstrate fast, efficient beam steering using a single 1x32 analog ferroelectric liquid crystal (FLC) spatial light modulator. A high-tilt FLC material with 82 degrees optic-axis switching provides, in a reflective-mode device with a passive quarter-wave retarder between a half-wave FLC layer and a mirror, 91% of full 0-2pi phase modulation. Electronic drive based on applied charge gives 200 micros response-time analog modulation.
    Language English
    Publishing date 2009-02-17
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/ao.48.001721
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Evaluation of a proposal for reliable low-cost grid power with 100% wind, water, and solar.

    Clack, Christopher T M / Qvist, Staffan A / Apt, Jay / Bazilian, Morgan / Brandt, Adam R / Caldeira, Ken / Davis, Steven J / Diakov, Victor / Handschy, Mark A / Hines, Paul D H / Jaramillo, Paulina / Kammen, Daniel M / Long, Jane C S / Morgan, M Granger / Reed, Adam / Sivaram, Varun / Sweeney, James / Tynan, George R / Victor, David G /
    Weyant, John P / Whitacre, Jay F

    Proceedings of the National Academy of Sciences of the United States of America

    2017  Volume 114, Issue 26, Page(s) 6722–6727

    Abstract: A number of analyses, meta-analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy ... ...

    Abstract A number of analyses, meta-analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy Agency, have concluded that deployment of a diverse portfolio of clean energy technologies makes a transition to a low-carbon-emission energy system both more feasible and less costly than other pathways. In contrast, Jacobson et al. [Jacobson MZ, Delucchi MA, Cameron MA, Frew BA (2015) Proc Natl Acad Sci USA 112(49):15060-15065] argue that it is feasible to provide "low-cost solutions to the grid reliability problem with 100% penetration of WWS [wind, water and solar power] across all energy sectors in the continental United States between 2050 and 2055", with only electricity and hydrogen as energy carriers. In this paper, we evaluate that study and find significant shortcomings in the analysis. In particular, we point out that this work used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions. Policy makers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that relies almost exclusively on wind, solar, and hydroelectric power.
    Language English
    Publishing date 2017-06-27
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.1610381114
    Database MEDical Literature Analysis and Retrieval System OnLINE

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