Exergy analysis of district energy systems and comparison of their exergetic, energetic and environmental performance

This paper investigates the advantages of performing exergy analysis for thermodynamic systems consisting of a district heating network (DHN) by comparing the exergy performance with energetic and environmental performance of three case studies in Austria. Furthermore, the effect of influential parameters such as energy source type, conversion technology, supply/return temperature and reference temperature on exergy performance of the system was investigated. An initial literature review and analysis of the case studies showed that the most influential factor on exergy performance of a system was the type of energy source and its conversion technology. Although lowering the supply temperature of DHN can increase the exergy efficiency of the system, changing reference temperature did not show a clear relationship with exergy efficiency. Finally, no clear relationship between energy and exergy efficiencies of the system was discovered; nevertheless, the higher the exergy efficiency of a system the lower the direct CO2 emissions from it

HotCity—A Gamified Token System for Reporting Waste Heat Sources

Urban planning needs to discover and incorporate new energy sources to meet climate protection targets in the future. Waste heat from industrial and urban infrastructure has proven to be a viable solution, but its proper identification can be challenging, especially for smaller and unconventional sources. Our project relies on the principles of gamification enhanced by a blockchain based token system and crowdsourcing as methods to collect and utilise spatial data such as the location and the size of previously unused heat sources. The mobile platform-neutral HotCity App en ables users to collectively patrol the city in search of waste heat sources and to gain tokens that can be exchanged for rewards. The blockchain platform Ardor was used for cheat proofing and to enable transparency for the reward system. The field test conducted in winter 2020/2021 showed high usability scores as well as high acceptance ratings of our approach opening up new use case scenarios in the context of spatial energy planning.©2022 Elsevier. This manuscript version is made available under the Creative Commons Attribution–NonCommercial–NoDerivatives 4.0 International (CC BY–NC–ND 4.0) license, https://creativecommons.org/licenses/by-nc-nd/4.0/fi=vertaisarvioitu|en=peerReviewed

Draft of innovation and research roadmap

sepponen2014ano abstrac

Modeling H2 formation in the turbulent ISM: Solenoidal versus compressive turbulent forcing

We present results from high-resolution three-dimensional simulations of the turbulent interstellar medium that study the influence of the nature of the turbulence on the formation of molecular hydrogen. We have examined both solenoidal (divergence-free) and compressive (curl-free) turbulent driving, and show that compressive driving leads to faster H2 formation, owing to the higher peak densities produced in the gas. The difference in the H2 formation rate can be as much as an order of magnitude at early times, but declines at later times as the highest density regions become fully molecular and stop contributing to the total H2 formation rate. We have also used our results to test a simple prescription suggested by Gnedin et al. (2009) for modeling the influence of unresolved density fluctuations on the H2 formation rate in large-scale simulations of the ISM. We find that this approach works well when the H2 fraction is small, but breaks down once the highest density gas becomes fully molecular.Comment: 13 pages, 8 figures, accepted for publication in MNRA

Draft of innovation and research roadmap

sepponen2014ano abstrac

Innovation and research roadmap

hukkalainen2015aThe READY4SmartCities (R4SC) project examines the adaption of Information and CommunicationTechnologies (ICT) in energy systems, in order to improve their sustainability and energy efficiency insmart cities. This deliverable presents an innovation and research roadmap, suggesting thedevelopment needs of ICTs in short, medium and long term for the holistic design, planning andoperation of energy systems. The focus is on large energy systems at the city level: centralized anddistributed energy systems with connections to both national level energy systems and to theneighbourhood and building level energy systems.The roadmap is divided into five roadmap sections: citizens, the building sector, the energy sector,municipality and energy data. Each roadmap sector introduces drivers, needs and requirements,visions, barriers, expected impacts and key stakeholders. In the following, the goals of the differentroadmap sections are specified from the viewpoints of key stakeholders. The role of ICTs and energydata in enabling these goals is also identified.The involvement of citizens in decision making related to energy aspects should be increased. Citizensshould take an active role in the operation and use of energy to improve their energy behaviour. ICTscould help citizens to improve their energy behaviour by making them aware of the impacts of theiractions.Buildings should become connected objects operating actively with energy networks and are optimizedto balance the energy behaviour and thereby maximize the comfort of the inhabitants. Efficient energyuse and on-site renewable energy production in the buildings is expected to be of high importance.Buildings could also be able to act as energy providers. This requires the smart use of data from thebuilt environment, energy grids, the weather etc., implying that interoperability is ensured at differentlevels.The energy supply in cities should rely both on distributed and centralised energy production with usingmany renewable and local energy sources. Cities would become large power plants and virtual storage,reacting flexibly on the availability of renewables. ICT standards are needed for the communicationbetween all the energy systems.Municipalities should foster the integration of different city systems to maximize their synergy impacts.Efficient energy use and supply could be realized through appropriate decision making, energyplanning, development projects and daily operation within cities. Energy supply and use are integratedto other city operations with various ICT solutions.Access to open energy data would enable the sharing of cross-domain data between differentstakeholders, leading to the consolidation of energy-related knowledge in cities. The use of energy datawould also give the stakeholders a holistic view of the energy systems.The repeating theme throughout the roadmap is a strong need for broad collaboration, communicationand interoperability within all the stakeholder networks. This requires the standardisation of bothinterfaces and systems themselves, to enable cross-organisational operation