{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T04:47:59Z","timestamp":1782190079854,"version":"3.54.5"},"reference-count":30,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T00:00:00Z","timestamp":1781568000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Supplying electricity, heat and cold is an essential part of the development of more sustainable city districts. Previous studies have illustrated interest in using the exergy efficiency concept to decompose the problem and rank the technology combinations for heating or cooling according to their overall efficiency. This methodology is extended herein to include network losses that depend on the temperature level and grid losses that play a role when comparing electricity supplied by the grid rather than by local cogeneration units. This extended method is then applied by considering two emerging technologies. The first is very-low-temperature district heating and cooling (DHC), directly supplying air-conditioning needs via simple heat exchangers, as well as heating needs via local heat pumps. It is part of what are called fifth-generation DHCs or \u201canergy networks\u201d and based on water or, better, on CO2 heat-transfer fluid. The main features of the five generations of networks, as well as the average aggregate user needs, are summarized in pinch technology composites, but replacing the temperature axis with a heat exergy axis to graphically highlight exergy losses. The average aggregate heating and cooling needs of users result from the application of a geographic information system to a district in a real city. The second emerging technology considers hybrid SOFC\u2013GT cogeneration units, with or without CO2 separation, supplying electricity to all network users, including decentralized heat pumps, while optimizing the recovery of waste heat. The full synergy between heat providers and users is highlighted, allowing districts without cooling towers or chimneys except at one energy balancing plant. Integration of the advanced SOFC\u2013GT cogeneration unit considered herein into the same anergy network allows an increase in exergy efficiency from 13.6% to 21.3%, as compared with electricity being supplied entirely from the grid and produced with a similar natural gas fuel.<\/jats:p>","DOI":"10.3390\/e28060693","type":"journal-article","created":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T05:56:31Z","timestamp":1781675791000},"page":"693","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Exergy Efficiency Is a Key Performance Indicator to Rank Advanced Active Energy Technologies at the District Level"],"prefix":"10.3390","volume":"28","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4545-0489","authenticated-orcid":false,"given":"Daniel","family":"Favrat","sequence":"first","affiliation":[{"name":"Energy Center, Ecole Polytechnique F\u00e9d\u00e9rale of Lausanne (EPFL), 1015 Lausanne, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,16]]},"reference":[{"key":"ref_1","unstructured":"IEA (2009). Outlook Report 2009, International Energy Agency."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Favrat, D., and Kane, M. (2025). Exergy Analysis of Heating and Cooling, Academic Press.","DOI":"10.1016\/B978-0-323-90496-4.00010-9"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Favrat, D. (July, January 30). Exergy efficiency is key performance indicator to rank advanced active energy technologies at the district level. Proceedings of the ECOS 2024, Rhodes, Greece.","DOI":"10.52202\/077185-0145"},{"key":"ref_4","unstructured":"Tani, F., Haldi, P.-A., and Favrat, D. (2010, January 14\u201317). Exergy-based comparison of the nuclear fuel cycles of light water and generation IV reactors. Proceedings of the ECOS 2010, Lausanne, Switzerland."},{"key":"ref_5","unstructured":"(2026, January 16). World Nuclear News. Available online: https:\/\/www.world-nuclear-news.org\/."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"130","DOI":"10.1016\/j.energy.2007.10.012","article-title":"The challenge of introducing an exergy indicator in a local law on energy","volume":"33","author":"Favrat","year":"2008","journal-title":"Energy"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.energy.2014.02.089","article-title":"Generation District Heating (4GDH) Integrating smart thermal grids into future sustainable energy systems","volume":"68","author":"Lund","year":"2014","journal-title":"Energy"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"107118","DOI":"10.1016\/j.scs.2026.107118","article-title":"Ensuring reliable district heating systems: Identifying critical components under independent and cascading failure scenarios","volume":"137","author":"Ding","year":"2026","journal-title":"Sustain. Cities Soc."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"120520","DOI":"10.1016\/j.energy.2021.120520","article-title":"Perspectives on fourth and fifth generation district heating","volume":"227","author":"Lund","year":"2021","journal-title":"Energy"},{"key":"ref_10","unstructured":"Acad\u00e9mie Nationale des Technologies (2014). Auteurs, Avis Sur Les R\u00e9seaux de Chaleur, Acad\u00e9mie Nationale des Technologies."},{"key":"ref_11","unstructured":"(2022, January 08). LeBlob: \u00ab R\u00e9cup\u00e9rer la Chaleur des Eaux Us\u00e9es \u00bb. (In French)."},{"key":"ref_12","unstructured":"Pelet, X., Pelet, X., Favrat, D., and Voegeli, A. (1997). Performance of a 3.9 MW Ammonia Heat Pump in a District Heating Cogeneration Plant: Status after eleven years of operation. Compression Systems with Natural Working Fluids; IEA Annex 22 Workshop, International Energy Agency."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"502","DOI":"10.1016\/j.apenergy.2017.10.072","article-title":"Bidirectional low temperature district energy systems with agent-based control: Performance comparison and operation optimization","volume":"209","author":"Wetter","year":"2018","journal-title":"Appl. Energy"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1016\/j.energy.2015.03.079","article-title":"Performance and profitability perspectives of a CO2 based district energy network in Geneva\u2019s city center","volume":"85","author":"Henchoz","year":"2015","journal-title":"Energy"},{"key":"ref_15","unstructured":"Page, J., Dorsaz, C., Rey, T., Mian, A., Henchoz, S., Chatelan, P., Girardin, L., and Duc, P.-J.D. (2023). R\u00e9seau de Distribution de Chaleur et de Froid Utilisant le CO2 Comme Fluide Caloporteur, Swiss Gas and Water Association. (In French)."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1016\/j.enconman.2026.121270","article-title":"Integrated optimization of adaptive CO2-based district and cooling networks into multi-energy systems","volume":"355","author":"Dicati","year":"2026","journal-title":"Energy Convers. Manag."},{"key":"ref_17","unstructured":"Vecchi, A., Rismanchi, B., Mancarella, P., and Sciacovelli, A. (July, January 27). Daily and seasonal thermal energy storage for enhanced flexible operation of low-temperature heating and cooling network. Proceedings of the 34th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2021), Taormina, Italy."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1099","DOI":"10.1016\/j.egypro.2017.07.443","article-title":"Potential and limitations of using low-temperature district heating and cooling networks for direct cooling of buildings","volume":"122","author":"Ruesch","year":"2017","journal-title":"Energy Procedia"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1016\/j.apenergy.2018.10.054","article-title":"Modelling development and analysis on the balanced energy networks (ben) in London","volume":"233","author":"Song","year":"2019","journal-title":"Appl. Energy"},{"key":"ref_20","unstructured":"Facchinetti, E. (2012). Integrated Solid Oxid Fuel Cell-Gas Turbine Hybrid Systems With or Without CO2 Separation. [Ph.D. Thesis, Swiss Federal Institute of Technology of Lausanne]. No 5323."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"565","DOI":"10.1002\/fuce.201000130","article-title":"Innovative hybrid Cycle Solid Oxide Fuel Cell-Inverted Gas Turbine with CO2 Separation","volume":"11","author":"Facchinetti","year":"2011","journal-title":"Fuel Cells"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"595","DOI":"10.1002\/fuce.201300196","article-title":"Design optimization of an innovative Solid Oxid Fuel Cell-Gas Turbine hybrid cycle for small scale distributed generation","volume":"14","author":"Facchinetti","year":"2014","journal-title":"Fuel Cells"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1016\/S0378-7753(03)00103-4","article-title":"Energy balance model of a SOFC cogenerator operated with biogas","volume":"118","author":"Marechal","year":"2003","journal-title":"J. Power Sources"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Clodic, D., and Younes, M. (2002, January 1\u20134). A new method for CO2 capture: Frosting CO2 at atmospheric pressure. Proceedings of the 6th International Conference Greenhouse Gas Control Technologies, Kyoto, Japan.","DOI":"10.1016\/B978-008044276-1\/50025-8"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"694","DOI":"10.1016\/j.ijggc.2010.11.011","article-title":"A novel process for cryogenic CO2 capture using dynamically operated packed beds\u2014An experimental and numerical study","volume":"5","author":"Tuinier","year":"2011","journal-title":"Int. J. Greenh. Gas Control"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"116728","DOI":"10.1016\/j.enconman.2023.116728","article-title":"Readiness evaluation of SOFC-MGT hybrid systems with carbon capture for distributed combined heat and power","volume":"278","author":"He","year":"2023","journal-title":"Energy Convers. Manag."},{"key":"ref_27","unstructured":"Page, J., Queen, W., Van Herle, J., and Agrawal, K. (2026, June 08). Inauguration du D\u00e9monstrateur \u00c9nerg\u00e9tique P2G, Sion. (In French)."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"571","DOI":"10.1016\/j.energy.2013.05.038","article-title":"Thermoeconomic design optimisation of a thermo-electric energy storage system based on transcritical CO2 cycles","volume":"58","author":"Morandin","year":"2013","journal-title":"Energy"},{"key":"ref_29","unstructured":"Girardin, L. (2012). A GIS-Based Methodology for the Evaluation of Energy Systems in Urban Area. [Ph.D. Thesis, Swiss Federal Technology Institute of Lausanne]. No 5287."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"830","DOI":"10.1016\/j.energy.2009.08.018","article-title":"Energis: A geographical information-based system for the evaluation of integrated energy conversion systems in urban areas","volume":"35","author":"Girardin","year":"2010","journal-title":"Energy"}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/28\/6\/693\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T04:12:27Z","timestamp":1782187947000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/28\/6\/693"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,16]]},"references-count":30,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,6]]}},"alternative-id":["e28060693"],"URL":"https:\/\/doi.org\/10.3390\/e28060693","relation":{},"ISSN":["1099-4300"],"issn-type":[{"value":"1099-4300","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,16]]}}}