Quantifying the Dunkelflaute: An analysis of variable renewable energy droughts in Europe

Quantifying the Dunkelflaute: An analysis of variable renewable energy droughts in Europe | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Quantifying the Dunkelflaute: An analysis of variable renewable energy droughts in Europe Martin Kittel, Wolf-Peter Schill This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7106203/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Feb, 2026 Read the published version in Communications Earth & Environment → Version 1 posted You are reading this latest preprint version Abstract Variable renewable energy droughts, also called “Dunkelflaute”, emerge as a challenge for climate-neutral energy systems based on variable renewables. Drawing on 38 historic weather years and an advanced identification method, we characterize European drought events for on- and offshore wind power, solar photovoltaics, and renewable technology portfolios. We show that their characteristics heavily depend on the chosen drought threshold, questioning the usefulness of single-threshold analyses. Applying a multi-threshold framework, we quantify how the complementarity of wind and solar power temporally and spatially alleviates drought frequency, duration, and severity within (portfolio effect) and across countries (balancing effect). We identify the most extreme droughts and show how these drive major discharging periods of long-duration storage in a fully renewable European energy system, based on a policy-relevant decarbonization scenario. Such events comprise sequences of shorter droughts of varying severity. The most extreme event occurred in winter 1996/97 and lasted 55 days in a perfectly interconnected setting. While the average renewable availability during this period was still 47% of its long-run mean, we argue that system planners must consider such events when planning for storage and other flexibility technologies. Methodologically, we conclude that using single calendar years is not suitable for modeling weather-resilient energy scenarios. Earth and environmental sciences/Environmental social sciences/Climate-change mitigation Earth and environmental sciences/Environmental social sciences/Energy and society/Energy supply and demand Scientific community and society/Energy and society/Energy supply and demand Variable renewable energy Energy droughts Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Published Journal Publication published 10 Feb, 2026 Read the published version in Communications Earth & Environment → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7106203","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":487562459,"identity":"4329604a-01ab-46e9-a2e7-6a7d1ff61630","order_by":0,"name":"Martin Kittel","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAqklEQVRIiWNgGAWjYDACHsYGIGkhx3AYxCFSS2PDAQYJY1K0MDCCtCQCCSK16PYcbn/8oUIive84jwHDmwoitJidbQQ67IxE7szDPAaMc84Qo+U80C8H2yRyNxzm3cDM20a0ln8S6QZgLf+IddjBBokEiJYGYrScOdg448wxCcOZh/k/HJxzjCgt6Q8+VNTYyPOdP5b44E0NEVpQwAFSNYyCUTAKRsEowAEAtJY96cvT40EAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-7229-5499","institution":"German Institute for Economic Research (DIW Berlin)","correspondingAuthor":true,"prefix":"","firstName":"Martin","middleName":"","lastName":"Kittel","suffix":""},{"id":487562460,"identity":"89167687-ee07-4765-815b-110acf7b77d6","order_by":1,"name":"Wolf-Peter Schill","email":"","orcid":"https://orcid.org/0000-0002-6981-7487","institution":"German Institute for Economic Research (DIW Berlin)","correspondingAuthor":false,"prefix":"","firstName":"Wolf-Peter","middleName":"","lastName":"Schill","suffix":""}],"badges":[],"createdAt":"2025-07-12 06:40:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7106203/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7106203/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s43247-026-03251-2","type":"published","date":"2026-02-10T05:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":104867710,"identity":"28be660d-49ca-44c6-9017-76f85289c79c","added_by":"auto","created_at":"2026-03-18 07:14:27","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":44127181,"visible":true,"origin":"","legend":"Article File","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7106203/v1_covered_4fa8a3ed-f8c1-490a-b793-3326ec0d060d.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Quantifying the Dunkelflaute: An analysis of variable renewable energy droughts in Europe","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Variable renewable energy, Energy droughts","lastPublishedDoi":"10.21203/rs.3.rs-7106203/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7106203/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Variable renewable energy droughts, also called “Dunkelflaute”, emerge as a challenge for climate-neutral energy systems based on variable renewables. 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