Heat Transfer and Energy–Exergy Analysis of Waste-to-Methane Valorization via Integrated Anaerobic Digestion–Sabatier System

Heat Transfer and Energy–Exergy Analysis of Waste-to-Methane Valorization via Integrated Anaerobic Digestion–Sabatier System | 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 Research Article Heat Transfer and Energy–Exergy Analysis of Waste-to-Methane Valorization via Integrated Anaerobic Digestion–Sabatier System Ekram Hadi alaskaree This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9056297/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract This study presents a comprehensive heat transfer and energy–exergy analysis of an integrated anaerobic digestion–Sabatier system for renewable methane production. The proposed configuration combines biologically optimized methane generation through mesophilic anaerobic digestion with electrochemical upgrading via modular Sabatier methanation. Thermal regulation of the anaerobic digester plays a key role in maintaining stable microbial activity and improving methane productivity under decentralized operating conditions. The anaerobic digestion unit operated at 35°C with a hydraulic retention time of 20 days, achieving methane concentrations of 60–65%. Incorporating water-assisted enhancement improved substrate–microorganism interaction and increased methane yield by approximately 30.5% compared with conventional digestion. Energy analysis demonstrated that biological methane production exhibits relatively low specific energy consumption, whereas the Sabatier upgrading pathway is strongly influenced by the high energy demand associated with hydrogen production. Exergy analysis revealed that the biological pathway experiences lower exergy destruction due to moderate temperature operation and reduced auxiliary energy requirements. In contrast, electrochemical upgrading introduces significant thermodynamic losses primarily related to upstream hydrogen generation. The integrated system achieved an estimated 42% reduction in CO₂-equivalent emissions compared with uncontrolled methane release scenarios. The results indicate that biologically optimized anaerobic digestion provides the most energy-efficient pathway for decentralized renewable methane systems, while Sabatier upgrading can serve as a complementary option under conditions of surplus renewable electricity. The proposed framework highlights the importance of heat transfer management and thermodynamic optimization for improving the performance and sustainability of waste-to-energy technologies. Anaerobic digestion Energy–exergy analysis Heat transfer Renewable methane Sabatier methanation Waste valorization Full Text Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 18 Apr, 2026 Reviewers invited by journal 14 Apr, 2026 Editor invited by journal 02 Apr, 2026 Editor assigned by journal 09 Mar, 2026 First submitted to journal 06 Mar, 2026 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-9056297","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":623162778,"identity":"b0d13595-5e2c-498c-be7c-2cce25d080ed","order_by":0,"name":"Ekram Hadi alaskaree","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5UlEQVRIiWNgGAWjYDACHjB5gIHhMPMBBhj7AJFa2BIgSonXcoDHAK4FL+DnOfvw0w2GO/J8x3m+bv7YxiDHdyOB8cAbPFoke9uNpXMYnhnOPMy77cbBNgZjyRsJDAfn4NFicJ6NAajlMOMGqJbEDUAth3nwaLE/z8b8G6jFfsNhnmcgLfUEtRjwtrGBbEkEamEDaUkwIKRF4swxNuscg8PJMw+zmd04c07CcOaZhw14/cLfk8Z8O6fisG3f+cPPblSU2QCDLvnwB3whBnUewlYgZmxgwOcwHIAMLaNgFIyCUTB8AQDipVh3K/YI2gAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0001-9586-9363","institution":"Middle Technical University","correspondingAuthor":true,"prefix":"","firstName":"Ekram","middleName":"Hadi","lastName":"alaskaree","suffix":""}],"badges":[],"createdAt":"2026-03-07 07:19:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9056297/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9056297/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107520290,"identity":"3554cf7a-1df2-4305-887d-7f1f5b4b69ab","added_by":"auto","created_at":"2026-04-22 08:59:42","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":584773,"visible":true,"origin":"","legend":"","description":"","filename":"EnergyandExergyPerformanceofWater.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9056297/v1_covered_db0d3dc3-84db-4390-9340-c0881c83e0c3.pdf"}],"financialInterests":"","formattedTitle":"Heat Transfer and Energy–Exergy Analysis of Waste-to-Methane Valorization via Integrated Anaerobic Digestion–Sabatier System","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"waste-and-biomass-valorization","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wave","sideBox":"Learn more about [Waste and Biomass Valorization](http://link.springer.com/journal/12649)","snPcode":"12649","submissionUrl":"https://submission.nature.com/new-submission/12649/3","title":"Waste and Biomass Valorization","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Anaerobic digestion, Energy–exergy analysis, Heat transfer, Renewable methane, Sabatier methanation, Waste valorization","lastPublishedDoi":"10.21203/rs.3.rs-9056297/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9056297/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study presents a comprehensive heat transfer and energy\u0026ndash;exergy analysis of an integrated anaerobic digestion\u0026ndash;Sabatier system for renewable methane production. The proposed configuration combines biologically optimized methane generation through mesophilic anaerobic digestion with electrochemical upgrading via modular Sabatier methanation. Thermal regulation of the anaerobic digester plays a key role in maintaining stable microbial activity and improving methane productivity under decentralized operating conditions. The anaerobic digestion unit operated at 35\u0026deg;C with a hydraulic retention time of 20 days, achieving methane concentrations of 60\u0026ndash;65%. Incorporating water-assisted enhancement improved substrate\u0026ndash;microorganism interaction and increased methane yield by approximately 30.5% compared with conventional digestion. Energy analysis demonstrated that biological methane production exhibits relatively low specific energy consumption, whereas the Sabatier upgrading pathway is strongly influenced by the high energy demand associated with hydrogen production. Exergy analysis revealed that the biological pathway experiences lower exergy destruction due to moderate temperature operation and reduced auxiliary energy requirements. In contrast, electrochemical upgrading introduces significant thermodynamic losses primarily related to upstream hydrogen generation. The integrated system achieved an estimated 42% reduction in CO₂-equivalent emissions compared with uncontrolled methane release scenarios. The results indicate that biologically optimized anaerobic digestion provides the most energy-efficient pathway for decentralized renewable methane systems, while Sabatier upgrading can serve as a complementary option under conditions of surplus renewable electricity. The proposed framework highlights the importance of heat transfer management and thermodynamic optimization for improving the performance and sustainability of waste-to-energy technologies.\u003c/p\u003e","manuscriptTitle":"Heat Transfer and Energy–Exergy Analysis of Waste-to-Methane Valorization via Integrated Anaerobic Digestion–Sabatier System","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-22 08:58:16","doi":"10.21203/rs.3.rs-9056297/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-04-18T09:14:22+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-14T18:45:57+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Waste and Biomass Valorization","date":"2026-04-02T19:44:05+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-09T11:52:10+00:00","index":"","fulltext":""},{"type":"submitted","content":"Waste and Biomass Valorization","date":"2026-03-07T02:19:27+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"waste-and-biomass-valorization","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wave","sideBox":"Learn more about [Waste and Biomass Valorization](http://link.springer.com/journal/12649)","snPcode":"12649","submissionUrl":"https://submission.nature.com/new-submission/12649/3","title":"Waste and Biomass Valorization","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5b79db5d-d401-4e35-a8e4-92a928544f02","owner":[],"postedDate":"April 22nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-22T08:58:17+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-22 08:58:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9056297","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9056297","identity":"rs-9056297","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}