International Sustainable Energy Conference - Proceedings
The ISEC - Proceedings cover the proceedings of the international ISEC conference taking place every second year.
TIB Open Publishing (Technische Informationsbibliothek (TIB))
Design and Comparative Analysis of a Renewable Energy Based Rural District Heating System
This research focuses on adapting renewable energy sources for high-temperature rural district heating systems. By utilising Polysun® software, simulations explore combinations of wood chips (biomass), air-water heat pumps, geothermal heat pumps and solar thermal. Emphasising carbon neutrality, the study considers the demand for space heating and domestic hot water. Data acquisition in Middle Franconia involved collecting relevant data from Hotmaps, considering the number of houses, construction year, and heated gross floor area. The study wraps up by presenting optimised models, empowering communities to make emission-effective decisions for sustainable heating solutions. This research contributes significantly to rural heating advancements, promoting energy efficiency and environmental sustainability. In our paper, we suggest solutions for rural energy communities with different technologies to reduce carbon emissions.
Copyright (c) 2024 Shrey Ayron, Thomas Haupt, Katharina Herkendell, Haresh Vaidya https://creativecommons.org/licenses/by/4.0
Planning Tools for Decentralized Heat Supply: Modeling the Effects of Volatile Renewable Energies
An increasing share of decentralized feed-in is necessary for the transition of district heating networks but it comes with various challenges. Software tools for modelling, simulation and optimization allow a theoretical examination of those challenges and possible solutions. Some of these have been used and further developed in the research project ZellFlex. One selected examination is the flexibility of supply temperatures by varying setpoint temperatures for a decentral solar thermal system (500 m²) integrated into an existing district heating network. The analysis of the supply temperature distribution in the network showed: A decrease of the solar thermal feed-in set point temperature by 5 K compared to the supply temperature of the central heat producer seemed acceptable in terms of security of supply, while a 10 K reduction comes with a high risk of undersupply. Furthermore, it was discovered that the points of time with the lowest supply temperatures at the consumers were just before and after they were provided with solar heat due to specific effects concerning temperature loss of the fluid.
Copyright (c) 2024 Vera Boß, Clemens Felsmann, Bogdan Narusavicius, Karin Rühling https://creativecommons.org/licenses/by/4.0
Decreasing the Return Temperature in District Heating Networks Thanks to a Switch to Alternative Substation Architectures
District heating networks (DHN) are key systems for managing heating and reducing carbon emissions at a large scale. Therefore, increasing their efficiency is a key to reduce climate change. DHNs with centralized production are supplying hot water to building substations (interface between the DHN and the buildings) for domestic hot water (DHW) production and space heating (SH) using heat exchangers. Colder water is returned to the centralized district heating system by the return pipe. One of the crucial factors to improve the efficiency of DHNs is to decrease the return temperature in the network to keep the same amount of energy transferred to the buildings while reducing the thermal losses and the flow rate, leading to more savings. In this paper, we model and simulate two of the most common DHN substation architectures used in a typical third-generation DHN to identify their flaws and propose new district heating substation architectures that can increase the DHN efficiency. The main result from our study is the consistent reduction in the average return temperature across all scenarios when implementing our proposed architectures. The reduction ranged between 3.7 °C and 10.2 °C. We also found that the lower the heating temperature, the greater the reduction. This is particularly beneficial as buildings are increasingly equipped with low-temperature heating systems, especially new constructions. Moreover, these architectures showed optimal efficiency with new buildings that have a high water heating demand compared to heating demand. This is due to the higher impact of cold water preheating.
Copyright (c) 2024 Gaétan Chardon, Rémi Patureau, Valentin Gavan https://creativecommons.org/licenses/by/4.0
Analysis of Industrial 5GDHC System in Ingolstadt
This study comprehensively examines the technical manifestation and planning process for a shared thermal energy network at a 75-hectare industrial area in Ingolstadt. Unlike traditional systems, this (5GDHC) network showcases a smart integration of energy flows across 70 buildings with a yearly heating demand of around 17 GWh and a yearly cooling demand of around 35 GWh. The network spans over 9,100 meters of piping with diameters up to 800 mm. With thermal power from various sources including 1.8 MW waste heat from a data centre and potential for 10 MW from the Danube River, the system epitomizes a dynamic balance of heating and cooling demands. The paper itself examines the planning process of the system and encompasses topics such as defining energy requirements and load profiles, assessing potential energy sources and sinks for enhanced system efficiency, and analysing pipe and network design. Through this investigation, the study provides valuable insights towards a methodology to facilitate the successful implementation of future industrial 5GDHC systems, furthering the cause of sustainable energy.
Copyright (c) 2024 Simon Nikolaus Müller, Rainer Strobel, Markus Faigl, Tobias Schrag https://creativecommons.org/licenses/by/4.0
Methodology for Fifth Generation District Heating and Cooling Network Simulation
5th generation district heating and cooling networks (5GDHC) will play a rolein the reduction of CO2 emissions and the resilience to global warming. Our analysis of the literature points out that no simulation study proposes a comprehensive enough description of such networks. The simulation solution presented in this article considers the intertwined influences between the thermal-hydraulic balance in the network, the behavior of the decentralized heat pumps and chillers at substations, and the thermal coupling with the ground. For a given simulation scenario, the 3 developed models are iteratively solved until convergence is reached. After showing how the latter is handled,we exhibit an original result about the influence of the differential pressure between the hot and cold pipes.
Copyright (c) 2024 Charlie Prétot, Nicolas Lamaison https://creativecommons.org/licenses/by/4.0
Evaluation of a Local Heating Network Supplied by a Pyrolysis Plant
In order to mitigate climate change, a wide range of negative emission technologies, such as pyrolytic carbon capture and storage, must be used in the future. This study therefore examines a specific application example for the energy supply with a pyrolysis plant that is operated with locally available biomass in the smallest district of the city of Freiburg. It is shown that such a supply concept is feasible and that the economic efficiency of the supply concept depends on the system output as well as the amount of local biomass and the revenues from the sale of the biochar. Of the six pyrolysis plants examined, two proved to be a promising alternative to the current wood chip boiler. By switching to an energy supply with a pyrolysis plant, the district could save several hundred tons of CO2 per year. The resulting total negative emissions would amount to almost 1200 tons of CO2 per year.
Copyright (c) 2024 Michael Schölles, Harald Bier, Björn Nienborg https://creativecommons.org/licenses/by/4.0
AbSolut - Integration of Absorption Technologies in District Heating and Cooling Systems for Enhanced Economic and Ecological Impact
District heating (DH) systems play a crucial role in meeting heating demands across the European Union (EU) and Austria, with significant potential for energy efficiency improvements and decarbonization. However, the transition towards climate neutrality by 2040 poses significant challenges, particularly in decarbonizing existing DH systems and integrating renewable energy sources. This work explores the application of absorption technologies, specifically absorption heat exchangers (AHX), absorption chillers (AC), and absorption heat pumps (AHP), in optimizing DH systems. The study investigates the utilization of AHX as transfer substations to increase heat capacity within existing grids by up to 30%, facilitating the integration of renewables and reducing distribution heat losses. Additionally, AC implementation for cooling supply demonstrates efficiency improvements through dynamic operation modes, renewable energy integration, and reduced electricity demand. Furthermore, AHP for waste heat utilization in DH power plants showcases environmental benefits, cost savings, and enhanced energy security. Through detailed techno-economic analyses and case studies, the paper evaluates the viability and economic feasibility of absorption technologies in DH applications. Challenges such as system integration, spatial requirements, and driving energy optimization are addressed, offering insights into overcoming barriers to adoption. Overall, the research highlights the transformative potential of absorption technologies in enhancing the efficiency, sustainability, and resilience of DH systems. By leveraging these technologies, DH operators and stakeholders can navigate the transition towards climate neutrality, while ensuring reliable and cost-effective heating and cooling solutions for urban areas.
Copyright (c) 2024 Carina Seidnitzer-Gallien, Carles Ribas-Tugores, Gerald Zotter https://creativecommons.org/licenses/by/4.0
Analysis of Different Climate-Neutral Heat Supply Concepts for a District Heating System near Munich with Deep Geothermal Heat as the Primary Heat Source
District heating systems are one key element of the transition towards a climate-neutral heat supply since they allow for the use of various renewable energy sources and the increase of renewable heat generation, in particular when combined with seasonal thermal energy storage. Deep geothermal heat is a renewable heat source that can be used to cover the thermal base load of such a district heating system. Also in combination with other renewable heat sources, such as solar thermal or heat pumps, a climate-neutral heat supply for districts or even complete cities can be realised. This paper deals with the analysis of different climate-neutral heat supply concepts that were elaborated for a district heating system currently in the planning phase using deep geothermal heat as the primary heat source, located in the town of Graefelfing near Munich, Germany. The authors present, discuss and assess various options regarding renewable heat sources and including (seasonal) thermal energy storage, to fully cover the thermal loads of a new district heating system in a technically, economically and environmentally favourable way. As a result of this study, a heat supply concept was selected, in which a heat pump using the return flow of the deep geothermal circuit as a heat source maximises the utilisation of the available deep geothermal heat source to cover more than 95 % of the annual heat demand by deep geothermal heat combined with a heat pump.
Copyright (c) 2024 Sven Stark, Stefanie Lott, Harald Drück https://creativecommons.org/licenses/by/4.0
Intermittent Operations of District Heating Networks in Summer Months
In the OREWA project, optimization measures for existing heat networks were identified and assessed based on both economic and ecological considerations [1]. One of the focal investigations was the simulation of intermittent operational strategies tailored for the summer months. Next to the classic intermittent approach an innovative variation was explored, which involved the storage of hot water during intermediate phases in large central tanks to further minimize heat losses. Both the classic and innovative intermittent strategies showcased substantial reductions in network losses and energy consumption for circulation pumps. This research shows the melioration of heat network efficiency through a substantial reduction of summer heat losses for a network with a low heat demand density of 0.7 MWh/(m²·a).
Copyright (c) 2024 Anna Vannahme, Simon Müller, David Schmitt, Thorsten Summ, Christoph Trinkl, Tobias Schrag https://creativecommons.org/licenses/by/4.0
Predict-IT - Forecasting District Heating Loads
In the realm of many thermal energy systems, and particularly within district heating networks, heat load forecasts play a pivotal role in optimizing system operation and efficient infrastructure usage. While district heating operators routinely log measurement data, its potential remains underutilized. One essential application of such data is forecasting a network’s heat load based on historical data records. Such forecasts can improve the efficient usage of plant infrastructure and facilitate predictive operational strategies. This paper introduces ”Predict-IT”, a web-based platform designed to standardize the entire forecasting pipeline, making the generation of predictions largely independent of expert knowledge. The Predict-IT platform is powered by a state-of-the-art long short-term memory (LSTM) based neural network algorithm which only requires very little inputs (measured heat load and ambient temperature) to deliver satisfying forecasting accuracy, even a couple of days ahead. The prediction algorithm is validated on two data sets from local Austrian district heating networks, showing the general applicability of the LSTM-based neural network, given an appropriate set of hyperparameters. The Predict-IT platform simplifies the process of forecasting heat loads into a few discrete steps: data upload, algorithm training, heat load forecast generation, and visualization of forecasts. The source code will be open-source, and deployment and installation will be facilitated by an easily installable Docker solution.
Copyright (c) 2024 Léo Bonal, Marnoch Hamilton-Jones, Zahra Nasrollahinayeri, Katharina Dimovski, Doris Entner, Philip Ohnewein, Harald Trinkl https://creativecommons.org/licenses/by/4.0
Integration of Solar Thermal Process Heat
Varying conditions for heat integration still make individual designs and planning for the Balance of Plant (BoP) necessary and slow down the market integration of solar heat for industrial processes (SHIP). In addition to increased costs for planning, this also leads to higher technical and project management risks due to the lack of standardized engineering procedures. Therefore, the goal of the MODULUS project is to design a modular standardization concept, which is developed during the planning and engineering phase of three commercial SHIP projects. For testing the functionality, test plans have been drawn up which are intended to provide initial guidance for tests and their criteria to be carried out in each case prior to delivery, cold and hot commissioning. The BoP of the plant in Turnhout (Belgium) has already been installed and commissioned on site. Its example will be used to discuss the procedure for commissioning in the present work. Furthermore, a survey was sent to 80 companies to evaluate the trends of the SHIP world market. Several trends are discussed that will have a significant impact on market developments in the coming years.
Copyright (c) 2024 Navina Konz, Timo Zippler, Jakob Leicht, Stefan Mehnert, Martin Scheuerer, Bärbel Epp, Andreas Burger, Dirk Krüger, Jana Stengler https://creativecommons.org/licenses/by/4.0
Evaluating the Potential for Solar District Heating with Pit Thermal Energy Storage in Sweden
Sweden was among the first countries to install solar thermal plants for district heating (DH) as early as in 1970s. However, in recent years, the focus on solar DH installations has shifted primarily to Denmark and Germany, with only one recent installation reported in Sweden. Nonetheless, due to changes in the overall heating market, the use of large-scale storage (both with and without solar heat) is becoming increasingly important. Despite significant advancements in adopting DH systems, the combination of solar DH with PTES is not well studied from Swedish context. The economic and geological prerequisites for the deployment of PTES remain largely unexplored. This paper explores the integration of large-scale solar thermal systems into DH networks in Sweden, particularly highlighting the feasibility and potential of pit thermal energy storage (PTES) systems. Through findings from a national project, this paper assesses the techno-economic-geological viability of PTES alongside solar thermal collectors, providing insights into the project’s methodological approach and initial findings.
Copyright (c) 2024 Puneet Saini, Urban Persson, Luis Sánchez García, Fredric Ottermo, Chris Bales https://creativecommons.org/licenses/by/4.0
SunPeek Open-Source Software for ISO 24194 Performance Assessment and Monitoring of Large-Scale Solar Thermal Plants
ISO 24194:2022, the first standard specifically designed to assess the operational performance of solar thermal collector arrays, is likely to have substantial impact on the entire solar thermal industry. This standard introduces the Power Check, a method that can be used for monitoring ongoing plant operation and for checking performance guarantees. However, its practical use is presently limited, as initial applications indicate a need for clarification, and it exists as a mere paper description, rendering it less accessible for plant designers and operators. Furthermore, any implementation necessitates practical decisions regarding data handling and algorithm implementation. Closed-source implementations, lacking a traceable and transparent framework, could lead to inconsistent results. To address these issues, this paper introduces SunPeek, an open-source software that provides a reference implementation of the ISO 24194 Power Check. SunPeek is freely accessible for both scientific and commercial purposes. This paper also discusses existing limitations of ISO 24194 and showcases five examples of SunPeek applied to real-life solar thermal plants. This underscores potential practical challenges, such as handling stagnation events, and highlights methodological progress, such as improved data filtering for performance analyses. The findings and applications indicate SunPeek’s usability and the high potential for ISO 24194-based performance monitoring of solar thermal plants.
Copyright (c) 2024 Daniel Tschopp, Philip Ohnewein, Marnoch Hamilton-Jones, Peter Zauner, Lukas Feierl, Maria Moser, Michael Zellinger, Christian Kloibhofer, Martin Koren, Stefan Mehnert, Alexis Duret, Xavier Jobard, Stefano Pauletta, Federico Giovannetti, Bert Schiebler https://creativecommons.org/licenses/by/4.0
Users' Impact on Buildings' Energy Performance Gap
Prior to implementation of new building (or building retrofit) projects, buildings' future energy demand is regularly predicted for certification or optimisation purposes. However, there is often a deviation between the projected and actual energy use during buildings' operation. A number of different factors can contribute to this mismatch that is typically referred to as energy performance gap (EPG). These could be due to uncertainties regarding weather conditions, buildings' systems, construction, and geometry. Specifically, issues regarding occupants' behaviour and related control actions have recently been suggested to be a major cause for the EPG. However, evidence for such a claim is not conclusive. In this context, this contribution explores the impact of occupants' control-oriented behaviour (e.g., interactions with buildings' control components and systems, such as opening or closing windows or adjusting thermostats) on buildings' energy performance. The present contribution entails critical reflections on these issues. Moreover, strategies are discussed that could balance occupants' control opportunities and energy efficiency targets.
Copyright (c) 2024 Christiane Berger, Ardeshir Mahdavi https://creativecommons.org/licenses/by/4.0
Uniform Modeling of Heat Production Costs in Single-Family and Multi-Family Houses
To ensure a fair and extensive comparison of different heating systems four representative buildings including their heat demand for space heating and domestic hot water were defined. A model for the heat production costs has been developed based on existing methods like the VDI 2067 part 1 [1] and the simplified approach for the calculation of the "Levelised Cost of Heat" (LCoH) of the IEA SHC Task 54 "Price Cost reduction in solar thermal systems" [2]. The developed model includes the costs of purchase, installation, operation, maintenance and disposal and was implemented in an EXCEL calculation tool which enables the calculation of the total life cycle costs (LCC), the levelized cost of heat (LCoH) and the CO2 emissions over the lifetime of the system.
Copyright (c) 2024 Stephan Fischer, Karl-Anders Weiß, Björn Nienborg, Katrin Lenz https://creativecommons.org/licenses/by/4.0
A Case Study of Nine Post-Hydrocarbon Ready Homes
A typical 2bed dwelling at Howgate Close, after 16months of occupation, has a daily average energy bill of 10pence/day/dwelling [1] It is proffered that Howgate Close may be the most energy efficient group of dwellings of its type, in the UK [2]. Howgate Close is a residential neighbourhood of nine single storey dwellings, operating free of fossil fuels, they are post-hydrocarbon ready. The development is located in Nottinghamshire, UK, and was completed in June 2022. All nine homes are a net annual generator of surplus renewable energy, with little to no heating demand. Six of the nine homes remain naturally heated, with no resort to the electric underfloor heating system. Exceptionally high levels of energy efficiency have been achieved with third-party verification, the As-Built SAP Rating of 143A [3] Such a rating places these homes in the top 0.01% of the 12million registered UK Energy Performance Certificate‘s (EPC) [4]. This paper provides a building Case Study that evidences performance standards making comparisons with the UK Building Regulation Compliance Standards [5] Howgate Close’s exceptional energy efficiency can be described as an aggregation of marginal gains [6] This paper is a prelude to more forensic analysis of Howgate’s in-use building performance, with the installation more advanced monitoring equipment in May 2024 for a period of two years. EWI Pro, Dr Harrall and Nottingham Trent University (NTU) are to undertake further data dissemination, providing a more forensic Howgate Case Study for ISEC 2025.
Copyright (c) 2024 Jeremy Harrall, Anton Ianakiev, Nicholas Miles https://creativecommons.org/licenses/by/4.0
BTTAB – Broad-Based Testing of Energy-Efficient Demonstration Buildings with Thermally Activated Building Components
The expansion of renewable energy generation as well as extensive possibilities for energy storage are central cornerstones of the energy transition. Thermal building component activation can be a key aspect here, as it can be used multifunctionally as a heating and cooling delivery system and as a storage system for fluctuating renewables. These applications not only offer enormous potential for the integration of renewable energies and waste heat, but they also promise high economic attractiveness and impress with their simplicity in implementation, operation and use. In order to investigate these properties of Thermally Activated Building Structures (TABS) on real buildings, in the study BTTAB [1] 18 demonstration buildings spread over Austria have been selected for monitoring and surveys. It is intended to provide information about the performance of the storage and energy flexibility potential on the one hand, and to generate essential findings with regard to user comfort, user satisfaction, economic aspects in construction and operation as well as functionality on the other. This paper highlights the various applications of the thermal building component activation technology and provides already derived results relevant for the planning, design and operation of future buildings with TABS.
Copyright (c) 2024 Paul Lampersberger, Walter Becke, Martin Mayr, David Wolfesberger https://creativecommons.org/licenses/by/4.0
Cost Optimal Analysis of Positive Energy Buildings
This paper describes the cost optimal calculation method for the techno-economic assessment of Positive-Energy-Buildings (PEBs) and applies this evaluation framework to two case studies in different climate zones. The approach is based on the EU supplementing guide-line 2012/C 115/01 and compares global costs and net primary energy demand of different energy technology packages. The case studies are residential buildings located in Valladolid, Spain (Mediterranean climate) and Helsinki/Kalasatama, Finland (Nordic climate). The results of the analysis reveals that not all PEB technologies are cost optimal and reduce global costs with current energy prices. Several factors affect the cost-effectiveness of the technologies, such as the shape of the building, the climate zone and the overall technological system in which they operate. Furthermore, results are very sensitive to calculation parameters such as electricity prices, discount rate and calculation period. The cost optimal analysis of case stud-ies in different climate zones indicates that PV and a change of the heating system are in most cases cost optimal technology solutions that reduce net primary energy demand and global costs. Lessons learned from this research can contribute to the definition of comprehensive evaluation frameworks aimed at optimizing, disseminating and replicating PEBs in Europe.
Copyright (c) 2024 Clemens Mayer, Andreas Tuerk, Ilaria Marotta, Raul Ciria Aylagas https://creativecommons.org/licenses/by/4.0
Positive energy districts (PEDs) are a vision to enable and foster the energy transition in the building sector. The integration of heat pumps (HP) in buildings and districts to achieve a net positive energy balance is crucial. The efficiency of the electric and thermal energy system of districts can be improved with the use of HPs. This refers to both, the upgrade of waste heat and benefiting from simultaneous use and generation of energy in buildings at different temperature levels (space heating, DHW, space cooling/dehumidification) and includes self-consumption of on-site renewable electricity generation. Using the example of the new district Innsbruck Campagne, HP integration options as well as photovoltaic (PV) integration potentials are evaluated with respect to reaching a positive energy balance. Both simulation results as well as monitoring results are presented. The importance of very high building efficiency standards as well as well-designed and dimensioned systems to achieve a positive energy balance and to reduce the so-called winter gap is highlighted.
Copyright (c) 2024 Fabian Ochs, Samuell Breuss, Elisa Venturi, Mara Magni, Georgios Dermentzis https://creativecommons.org/licenses/by/4.0
Digital planning today is based on Building Information Modelling (BIM); this method greatly profits from the approach of defining use cases that lead through the process. As such, a use case for functional tests of the Heating Ventilation and Air Conditioning (HVAC) systems is currently being developed that begins in design development phase of the planning process. Additionally, a use case concerning the linkage between open BIM and the dynamic simulation software IDA ICE is also under development. First results of these use case developments will be presented in this work, along with the challenges of working in open BIM environment using the open BIM standard Industry Foundation Classes (IFC).
Copyright (c) 2024 Anita Preisler, Sama Schoisengeier, Gerhard Zucker, Alina Stipsits https://creativecommons.org/licenses/by/4.0
How Can Non-Intrusive Load Monitoring Contribute to the Assessment of the Smart Readiness Indicator?
The Smart Readiness Indicator (SRI) is a framework introduced by the EU in 2018 to assess smart buildings in various aspects. However, the SRI has been criticized for several limitations, including its ambiguous service definitions. This paper proposes the application of Non-Intrusive-Load Monitoring (NILM) technology to enhance SRI evaluation on the example of SRI service E-12. NILM can be used to disaggregate energy consumption data to end use levels and allows for granular non-intrusive energy consumption measurement. The study involves a rigorous methodology using open sensor data and NILM algorithms to evaluate device-specific energy consumption We evaluate the IDEAL dataset and three different frequencies (5s, 15min, 1h), three different algorithms (CO, RNN, Seq2Point) and one data imputation strategies (forward filling). The results show that with a higher frequency, the performance metrics (F-score, normalized absolute error) increase. Regarding further considerations, we identify a trade-off between resource and energy efficiency, as well as privacy considerations with increasing measurement frequency. To achieve its aims for awareness, the SRI needs to consider interoperability and appropriate aggregations (frequency and spatial).
Copyright (c) 2024 Felix Rehmann, Siling Chen, Falk Cudok, Rita Streblow https://creativecommons.org/licenses/by/4.0
BuildingTwin - Open Platform for Monitoring, Evaluation and Optimization of Building Operation
Keeping track of all data about a building over its entire life cycle is a major challenge. Planning data, like the building information modeling (BIM) data, is often not carried over into the operational phase. The "as-built" state is commonly documented in various lists and data sheets, independently of the BIM model. And usually neither real-time nor historical data on the operating status of the building is available. This lack of data makes it hard to operate a building in an optimized and efficient manner. We demonstrate the web-based platform "buildingTwin" to aggregate all building relevant data in a centralized "digital twin" model of the building, combining BIM data from the planning phase, data sheets and attributes documenting the "as-built" state, and real-time measurements from sensors and other sources during the operational phase. This platform provides easy access to all building data and enables monitoring, evaluation, and optimization of the building operation.
Copyright (c) 2024 Andreas Riffnaller-Schiefer, Tobias Weiss https://creativecommons.org/licenses/by/4.0
Flexibility Potential in the Austrian Building Sector
What would happen if 15% of the Austrian building stock in 2030 – both refurbished and newly-built – would use flexible heating/cooling systems to offer their flexibility on a market? How much annual residual loads from volatile renewable energy sources (RES) could be absorbed? Our simple agent-market model says: ~5% of RES surpluses and around 2% of RES residual loads. The cost of this operation is additional energy demand of about 30%, indicating an efficiency of approx. 70% in using these volatile supply peaks in flexible building operation. In this model, buildings are agents offering additional electricity consumption from pre-emptive HVAC operation, effectively using the building mass as storage, their energy demand is modelled in a simple thermal RC model. The grid flexibility demand is derived from future residual load scenarios and the offered flexibility depends both on signal parameters, mainly signal frequency and duration, and on key building parameters indoor temperature comfort bounds, building mass and thermal envelope quality.
Copyright (c) 2024 Raphael Drexel, Simon Schneider https://creativecommons.org/licenses/by/4.0
A use case driven design approach of an energy data exchange platform
The current digitalization of energy systems, particularly in urban contexts, lags behind the requirements set by urban energy system modelling, energy management, the development of digital twins, and other data-driven services. Additionally, existing energy data lacks standardized formats and coherence, hindering its full utilization. To address this challenge, this paper introduces a use case-driven design approach tailored to reflect the requirements for data integration and privacy set by city stakeholders. The objective is to design a data exchange platform (DEP) capable of serving a diverse range of use cases. This platform will facilitate the integrated utilization of energy data in energy management systems, digital twin applications, and other activities aimed at extracting valuable insights. These efforts are specifically designed to support decision-making processes of public stakeholders, private investors, and service providers. Consequently, the platform holds potential to attract additional investments in both the clean energy transition and the digitalization of energy infrastructure.
Copyright (c) 2024 Daniel Horak, Lukas Lorenzen, Jan Kurzidim, Ali Hainoun https://creativecommons.org/licenses/by/4.0
Renewable Gasfield – Lessons Learned From Commissioning Towards Stable Operation
Two years ago, the concept of the Renewable Gasfield Gabersdorf was introduced during the ISEC 2022 conference. Now, two years later, we are able to present our “real-life” experience which we made in the meantime, covering the authority engineering process, the construction period and – most important – the start-up and commissioning process. In this period not only the P2G-plant was set into operation, but we also saw an increasing number of hours with a surplus of solar electric power produced in the surrounding countryside. So, at several hours throughout the year, the electric power output of the already existing solar parks had to be reduced in order to maintain a stable electric grid. Although the PEM-electrolyser with 1.4 MW total electric power uptake is still to be considered as a small-scale project, it becomes obvious that the concept of producing green hydrogen and then using this hydrogen to upgrade raw biogas to pure biomethane will be a perfect concept to store a surplus in electric power permanently in the existing natural gas grid.
Copyright (c) 2024 Bernhard Mayr, Stephan Daniel, Patrick Passail, Stefan Fink, Andreas Kainz https://creativecommons.org/licenses/by/4.0
Investigation of the Flexibility Potential by Decoupling Building Mass and Room Temperature
Using the thermal building mass as a thermal storage received increasing attention in research during recent years. Due to the large mass of concrete, it offers a large storage capacity and thus a high potential for flexibility. However, passive heat losses during cool down of a thermally activated building influence room temperature and thus limit its flexibility potential. In this contribution a multi-layer activation concept was investigated which thermally decouples the building mass and room air. The study aims to analyse the cool down of a thermally activated building in terms of different charging parameters while considering other heat sources such as solar gains. A dynamic building simulation of a demonstration building was set-up and compared to simulative studies from literature to proof the validity of its dynamic behaviour. In the simulation model the room temperature could be kept above 19 °C between 100 - 190 h. However, when charging the building structure quickly, room temperatures above 24 °C are reached easily. Considering other heat sources such as solar gains, advanced control algorithms are required for efficient operation of the heating system.
Copyright (c) 2024 David Schmitt, Tobias Reum, Thorsten Summ, Christoph Trinkl, Tobias Schrag https://creativecommons.org/licenses/by/4.0
Dimensioning Method for PVT Collectors as Heat Source of Heat Pumps for Residential Buildings
Photovoltaic-thermal (PVT) collectors are an emerging technology that is increasingly being used as a heat source for heat pump systems in residential buildings. However, a suitable standard methodology for sizing the PVT collectors for these systems is still not available. This paper initially provides a framework for the sizing of a PVT-heat pump system for small houses according to the German guideline VDI 4645. The dimensioning method of VDI 4645 and the sizing method for PVT collectors are incorporated in a web-based tool that is aimed to assist planners (or homeowners) during the preliminary planning of a heat pump system in single and multi-family houses. The methodology also covers the planning of systems with backup/additional heaters (e.g. gas boiler and heating rod), e.g. for buildings with limited roof areas for PVT installations. Different heat pump operation modes, i.e. monovalent, bivalent-alternative, or bivalent-parallel are also considered. A model of the IEA SHC Task44 SFH100, an existing single-family house with radiators, has been chosen as an example case to demonstrate the methodology. For the evaluation of the performance of the designed system, yearly simulations of the system are done in TRNSYS. The results show that the developed methodology provides plausible sizes for the example case. However, further development and validation are necessary to provide flexibility in system dimensioning.
Copyright (c) 2024 Krishna Timilsina, Bharat Chhugani, Harshvadan Modi, Peter Pärisch https://creativecommons.org/licenses/by/4.0
A Review of Possibilities and Challenges of Pit Thermal Energy Storages in Swedish District Heating Networks
The use of pit thermal energy storages (PTES) enables higher solar fraction in district heating networks by counteracting the mismatch between heat demand and production in solar district heating (SDH) installations. Capital costs linked to land areas with site-specific geological conditions are the deciding factors for PTES constructions. This study investigates non-technical and technical factors for the implementation of PTES in Swedish district heating networks. Having several SDH and PTES installations in operation the country of Denmark is used as a reference. This study, based on literature review, discusses the drivers and challenges for the use of PTES in district heating networks.
Copyright (c) 2024 Frej Fogelström, Itai Danielski, Truong Nguyen, Gireesh Nair https://creativecommons.org/licenses/by/4.0
Thermally Activated Building Structures as Flexibility Option for the Electricity Market
Combined with heat pumps, thermally activated building structures (TABS) can serve as a resource of flexibility for electricity markets and the grid. This paper analyses the energy-economic value resulting from utilising the flexibility enabled by thermal building inertia. The scope of the study is the Austrian building stock by the year 2040. A specific business model for using the flexibility from heat pumps in buildings is being developed in the PnP Control TABS research project. This paper also gives insights into the controller logic developed and first results from a demonstrator.
Copyright (c) 2024 Guntram Preßmair, Wolfgang Amann, Alina Stipsits, Sama Schoisengeier, Florian Wenig https://creativecommons.org/licenses/by/4.0
Agent-Based Modelling of Policy Interventions on District Heating Adoption
This study employs an agent-based model to examine the adoption of District Heating Networks (DHNs) in heat zoning areas, focusing on the impact of three policy interventions, subsidy, tax and mandating connections. Analysing a case in South Yorkshire, UK, the research highlights a notable synergy in policies, with a combined £25.5 million from subsidies and tax incentives leading to a 28% (£33 million) reduction in infrastructure costs. The policies accelerated the DHN connection rate, achieving full coverage by 2028, two years ahead of the baseline scenario. Investment costs per household were significantly reduced from £2000 to £1460, aligning with governmental cost projections. The study acknowledges optimistic connection rates and suggests future work to include realistic project timelines and incorporate social and behavioural factors in DHN adoption. The findings show the effectiveness of integrated policy frameworks in promoting DHNs.
Copyright (c) 2024 Thomas Cowley, Timothy Hutty, Solomon Brown https://creativecommons.org/licenses/by/4.0
Linking Renewable Energy Projects at Municipal Level with NECP Planning and Reporting
Regarding the National Energy and Climate Plan (NECP) according to EU Governance Regulation, there is a disconnect between the federal and municipal levels that hinders effective planning and reporting, especially in the area of renewable energy sources (RES) where availability depends on the regional spatial conditions. The project transFORMAT-LINK addresses this challenge based on case studies and stakeholder discussions. Main results are (1) the LINK-Guideline for municipal development concepts/plans to support RES project implementation and NECP planning and reporting; (2) the LINK-Software prototype for developing and monitoring municipal development concepts/plans according to LINK-Guideline. This contribution presents an overview of preliminary results, with a focus on minimum requirements for municipal development concepts/plans under the regional spatial planning laws and how they will facilitate the implementation of renewable energy projects.
Copyright (c) 2024 Susanne Geissler, Abraham Arevalo-Arizaga, Daniel Youssef, Hartmut Dumke, Elias Grinzinger https://creativecommons.org/licenses/by/4.0
REA: Resource Exergy Analysis – A Key to Climate Sustainability
Resource exergy analysis (REA) is a method to comprehensively assess the resource consumption of technical systems. It is based on the physical property “exergy”, which goes beyond conventional energy analysis by considering energy quality. Combining exergy with a scientific definition of natural resources, REA can provide a comprehensive quantification of the resource consumption caused by any demand. REA introduces resource exergy consumption as a new key metric for the assessment of technical systems. In combination with an assessment of the direct greenhouse gas emissions, it allows quantifying climate sustainability consistently. The use of REA can be a key to climate sustainability by helping to minimize wastefulness and, consequently, indirect greenhouse gas emissions. In this paper, a sample comparison using REA and a complementary greenhouse gas analysis is provided that illustrates why REA is a key to assessing the climate impact of technologies more comprehensively than with many alternative methods. Specifically, the following systems are compared: heat supply using an individual natural gas boiler, an individual boiler using green hydrogen from wind power and district heating generated with a large heat pump using wind power. To illustrate the differences, exergy passes are used. They are a visualization tool to make REA results more transparent. The sample analysis illustrates how REA helps to avoid greenwashing and thus support climate sustainability by complementing direct greenhouse gas emissions analysis.
Copyright (c) 2024 Andrej Jentsch https://creativecommons.org/licenses/by/4.0
Heating the Future: Overcoming Challenges and Gaining Stakeholder Support for District Heating Transformation
District heating plays an important role in many studies and scenarios for reaching greenhouse gas neutrality in Germany’s heating sector. In some scenarios, the share increases to up to 30 % of the final energy demand for heat supply in buildings. Expanding and transforming district heating will not occur without significant effort; it will take a deliberate approach and appropriate measures to successfully achieve these goals. Technical and organizational challenges must be addressed, along with securing support and promoting social acceptance and active societal support among the various stakeholders. Therefore, in this research, barriers, and potential solutions are analyzed for the seven main stakeholder groups involved and affected by the extension and transformation of district heating in Germany. Furthermore, this study examines and discusses methods to increase acceptance and active societal support in Denmark, the Netherlands and France, based on literature, interviews and two stakeholder workshops. Consequently, measures to increase acceptance of and active societal support for district heating in Germany are specified.
Copyright (c) 2024 Benjamin Köhler, Jessica Berneiser, Veit Bürger, Caren Herbstritt, Katja Hünecke https://creativecommons.org/licenses/by/4.0
Photovoltaic and Solar-Thermal Use Case Application Comparison with Witness Simulation and DCF Analysis
In this work, we investigate a system of solar and thermal heat collectors in combination with local and electric net storage. The system is implemented in a Witness Horizon simulation model, allowing for the investigation and scenario analysis of different use cases. In a practical industrial application example use-case, using simulation and Discounted Cash Flow (DCF) analysis, the economic feasibility of the best system variant could be calculated. The developed model includes the local consumption and production profile and it was evaluated by a DCF model after the dynamic energy modelisation with the generic industrial production system simulation software WITNESS Horizon. This model can be in future further extended to generic and more complex production systems, simultaneously integrating the DCF cost evaluation analysis and following direct economic optimisation as well as integrating it with the production portfolio theory approach by integrating diversified virtual production market aspects and market goal-oriented optimisation.
Copyright (c) 2024 Bernhard Heiden, Karl Gaugg, Volodymyr Alieksieiev, Bianca Tonino-Heiden https://creativecommons.org/licenses/by/4.0
Towards a Digital Representation of Building Systems Controls
Energy monitoring and performance optimization processes play a significant role in ensuring energy-efficient building operation. However, the current implementation of these processes requires substantial time and effort due to the fragmented and non-digital nature of technical building equipment information. To address these challenges, we demonstrate the application of the PLCont methodology within an ongoing monitoring process in a real building. PLCont utilizes Semantic Web Technologies and established RDF ontologies to describe the control topology. The digital representation of control functions aligns closely with the IEC standard 61131-3, and the PLCont ontology establishes a connection between the topology and the control functions. We compare the conventional approach and the PLCont methodol-ogy using the supply air temperature control of an Air Handling Unit (AHU) as a use case. A graphical user interface built upon the PLCont backend provides a comprehensive represen-tation of the system's functionality. It displays the system topology as a digital HVAC schema, the function code exported from the PLC, time-series data plots, and textual descriptions of implemented functions. We demonstrate how this approach enhances transparency and facil-itates the identification and elimination of faulty system behavior, ultimately contributing to the optimization and energy efficiency of building systems.
Copyright (c) 2024 Moritz Ihlenburg, Nicolas Réhault, Sebastian Herkel, Gesa Benndorf https://creativecommons.org/licenses/by/4.0
Performance Assessment of Novel Transparent Insulation Materials for Integrated Storage Collectors
Transparent insulation structures play a pivotal role in harnessing solar energy efficiently, akin to the greenhouse effect in the atmosphere. This study undertakes a systematic evaluation of a novel sorbitol- or bio-based polycarbonate (bio-PC) for thermal insulation (TI) structures and hot water collector systems. Employing optical and mechanical methods, the bio-PC was comprehensively characterized on the polymer film level. Subsequently, the technical and ecological performance of these structures in various hot water collectors and systems was rigorously modelled and simulated. Results indicated that the novel bio-PC exhibited superior properties compared to conventional materials like cellulose acetate or fossil-based PC, showcasing promising prospects for widespread adoption. Drawing parallels to the greenhouse effect of CO2, the functional principle of transparent insulation structures is rooted in high solar transmittance and infrared absorbance, primarily governed by carbon-oxygen bonds. While fossil-fuel based transparent insulation materials have been prevalent, they suffer from drawbacks such as average infrared absorbance and susceptibility to yellowing. In contrast, the newly introduced bottom-up biopolymer bio-PC, derived from sorbitol derivatives, offers a compelling alternative. The study sheds light on the potentials and limitations of bio-PC for transparent insulation structures in integrated storage or flat plate collectors, aiming to mitigate environmental impacts associated with traditional materials. Future research directions emphasize refining modelling tools and addressing input data deficiencies, particularly for life cycle analysis. Concurrently, efforts are directed towards enhancing simulation accuracy and reliability through concurrent measurements of collector systems equipped with bio-PC-based transparent insulation. This research underscores the critical role of innovative materials in advancing sustainable energy solutions, with bio-PC emerging as a promising candidate in the realm of transparent insulation technology.
Copyright (c) 2024 Harald Kicker, Jonas Segsulka, Gernot M. Wallner https://creativecommons.org/licenses/by/4.0
Integrated Energy Solutions: A Call for Inclusion of Non-Technical Factors
The central supposition put forward in this paper is that typical building-related energy efficiency measures do not automatically yield the looked-for large-scale environmental effects. Rather, many such measures entail two kinds of reductionism, in that they i) treat buildings detached from the larger system (such as the urban context), to which they belong; ii) concentrate on solutions, which are predominantly technological in nature. As a consequence, the complexity of the challenge may be neglected, along with other non-technical, yet potentially critical areas of concern. Such areas include, inter alia, economy, politics, policy, as well as societal and psychological circumstances. In this paper, we discuss a few typical instances of such reductionist stances to shed light on factors that impede their utility. Moreover, we highlight a few instances of systemic methods that have been suggested as having the potential to address complex problems in general, and the environmental implications of energy efficiency measures in the context of the built environment in particular.
Copyright (c) 2024 Ardeshir Mahdavi, Christiane Berger, Neda Ghiassi https://creativecommons.org/licenses/by/4.0
Energy Production, Efficiency and Flexibility for Positive Energy Districts: A Review
In 2018, EU launched the programme “Positive energy districts and neighbourhoods for sustainable urban development” with an aim to support the planning, deployment and replication of 100 Positive energy districts (PEDs) by 2025. This is an ambitious target considering the various challenges on implementing PEDs. This paper, based on literature review, provides an overview on the challenges and possibilities on the three main components of PEDs; energy production, energy efficiency and energy flexibility.
Copyright (c) 2024 Gireesh Nair, Moa Mattsson, Eser Delice, Ipek Gursel Dino https://creativecommons.org/licenses/by/4.0
Heating and Cooling with Renewable Energy from Wastewater
Energy from wastewater is recognized as a renewable energy source and can add a valuable contribution to the EU’s path to decarbonization. With modern heat exchangers and heat pumps, buildings and districts can be supplied with energy for heating, cooling and water heating. Based on the successful results of the implementation in Vienna Blumental, another project in Vienna has been rolled out: The Vio Plaza building complex will be supplied with energy from wastewater for heating (1.2 MW) and cooling (6 MW). This article presents the case study at Vio Plaza, gives a detail description of the system design and delivers first-hand information about operation of the installed system. Special focus is put on the innovative monitoring system and resulting monitoring data, which prove the good operation of the system. Based on these results, further knowledge about these systems will be gained to support the increasing implementation of this technology.
Copyright (c) 2024 Flora Prenner, Rainer Wiedemann https://creativecommons.org/licenses/by/4.0
Use of Waste Heat Potential and Flexibility Elements to Speed up Decarbonisation in Austrian Thermal Spas
Austria's 38 thermal baths offers a unique opportunity to harness deep hydrothermal geothermal energy, reducing their reliance on fossil fuels and decreasing CO2 emissions by over 50,000 tonnes annually. The GEOMAT project's core focus is on efficiency enhancement by integrating various heat pump technologies, optimizing energy management, and transitioning to renewable energy sources for complete decarbonization. Geothermal energy is pivotal for Austria's sustainable energy future, with a particular emphasis on making it economically appealing for significant energy consumers, including thermal spas, municipalities, energy providers, and industries. By leveraging innovative heat pump systems and intelligent control concepts, GEOMAT aims to maximize energy efficiency and create flexibility in electricity and heating networks, thereby fostering synergy and systemic benefits.
Copyright (c) 2024 Carina Seidnitzer-Gallien, Roman Stelzer, Sebastian Dragosits https://creativecommons.org/licenses/by/4.0
Improving Energy Efficiency of Carbon Capture Processes with Heat Pumps
Carbon capture based on chemical absorption in amine-based solvents is the most relevant technology option to reduce CO2 emissions from hard-to-abate industrial CO2 sources and power plants. Because of the energy consumption of the carbon capture process, which is mainly attributed to heating the desorber, carbon capture has a negative impact on the efficiency of the process where CO2 is removed. Heat pumps allow for heat recovery and provide high temperature process heat. Due to recent developments, heat pumps are now capable of supplying steam and providing high temperatures enabling new applications. This contribution investigates the integration of heat pumps into the carbon capture process of a furnace for steel processing to determine the most suitable heat sources and sinks and the achievable energy savings. The energy consumption of the carbon capture process can be lowered by 50% due to the integration of steam generating heat pumps. The cost analysis shows that the costs of steam have the highest influence on the costs of captured CO2.
Copyright (c) 2024 Veronika Wilk, Daniela Leibetseder, Christoph Zauner, Andreas Rath, Michael Schwaiger https://creativecommons.org/licenses/by/4.0
Biomass to Bioenergy in the Province of Huíla, Angola
The search for cleaner energy sources in Angola has grown significantly due to the need to reduce the dependence on diesel generators to supply electricity, which, combined with the fossil fuels consumption in the transport and industrial sectors, puts the country on the path of those who have increased the greenhouse gas emissions over the last years. Only 30% of the population has access to electricity despite the country's extensive resources of hydroelectric power and fossil fuels. Vegetable biomass accounts for 65% of the country's primary energy supply, and 80% of the rural population depends on it to meet most of their energy needs. This biomass is burned in poor-quality devices, making them inefficient and causing health issues for the users exposed to the combustion gases. Therefore, this work aims to evaluate options for a greener and more sustainable use of biomass to bioenergy, and different scenarios were built based on the current use of biomass. Results show that the use in the Province of Huíla of the biomass residues could replace by 50% the firewood. The replacement of the three-stone fire by using more efficient cooking stoves will reduce the amount of biomass needed and therefore, the residues from the province would suffit the demand to cook. The use of those more efficient stoves will also allow a reduction of harmful emissions. However, changing the stoves by more efficient ones also result in an economical burden that may not be reached by most rural populations.
Copyright (c) 2024 Fernando Cativa, Jorge Costa, Ana Luísa Fernando https://creativecommons.org/licenses/by/4.0
Renewable Hydrogen Supply Scenarios for Inland Waterway Transport in Europe
The European inland waterway transport needs to substitute 6.2 TWh of fossil diesel by renewable energy carriers. For hydrogen retrofit solutions investigated in the European project “Synergetics”, different Well-to-Tank pathways have been analysed to supply renewable hydrogen to Rotterdam, including buffer storage and fuelling to vessels. This paper compares two dominant scenarios with regards to GHG emissions and costs. One scenario is based on PV electricity from Morocco, transported to Rotterdam for electrolysis. The other scenario is calculated with electricity from offshore wind farms in the Northern Sea. The calculation of the PV scenario leads to specific emissions for the hydrogen supplied to vessels of 51 gCO2eq/kWhH2 with levelized costs of hydrogen of 0.12 €/kWhH2. The wind scenario led to 16 gCO2eq/kWhH2 with 0.19 €/kWhH2. The electrolysis has the highest impact on emissions and costs, especially the electricity demand. Accordingly, lower emissions of PV electricity supply would have a high influence on the overall results. On the other hand, for the low emission renewable hydrogen supply with wind power a further reduction of the costs of the installation will be relevant.
Copyright (c) 2024 Elimar Frank, Luca Stauss https://creativecommons.org/licenses/by/4.0
Replacing Fossil-Fueled Combined Heat and Power Plants with Malta’s Pumped Heat Energy Storage Technology to Provide Clean Power and District Heat
This study analyzes the potential integration of a 100 MWel, 36-hour Malta Pumped Heat Energy Storage (PHES) system into the district heating network of the city of Hamburg, Germany, using energy from a nearby offshore wind farm that would otherwise be curtailed to charge the system. Publicly available data showing the times when curtailment instructions were given by the transmission system operator were used to determine the hours during which the storage system should be charged. Malta’s proprietary hourly performance model was used to simulate the behavior and performance of different plant configurations. It was shown that this configuration could avoid the curtailment of 227 GWhel of wind energy per year. The study showed that the system could provide 117 GWhel of electricity to the grid, as well as 72 GWhth of thermal energy for Hamburg’s district heating network, during periods where less renewable energy was available. This system could reduce the annual CO2 emissions by 101,400 tonnes compared to the coal-fired combined heat and power (CHP) plant that it would replace.
Copyright (c) 2024 Finn Runkel, Janina Hippler-Nettlau https://creativecommons.org/licenses/by/4.0
Using Hydrogen to Decarbonize the Brick and Tile Industry
For a significant reduction of carbon dioxide (CO2) emissions, it is assumed that hydrogen (H2) will substitute natural gas in the upcoming years. Therefore, the operational limitations of the existing burner technology must be evaluated when the hydrogen content in the fuel is increased. To investigate the H2-readiness of typical burners, numerical simulations and experimental investigations were carried out in test facilities and in an industrial tunnel kiln system in the brick and tile industry. The results of the examination of the existing conventional burner for natural gas and an additive manufactured dual-fuel burner for natural gas and H2 will be presented. The investigations carried out so far suggest that it is possible to use H2 in addition to natural gas as a fuel gas for tunnel kilns in the brick and tile industry. Ongoing investigations by means of simulations and measurements of the industrial tunnel kiln will provide further insights into this.
Copyright (c) 2024 Stefan Wallat, Wolfgang Adler, Ekhard Rimpel, Rigo Giese https://creativecommons.org/licenses/by/4.0
Sustainable Heat Supply for Greenhouses with Heatpumps
The heating of greenhouses in Germany is yearly responsible for the emission of about 3 million tCO2eq. In the small horticultural city of Straelen in North-west Germany, the possibility to partially replace the heat supply of greenhouses with heat pumps instead of CO2-intensive coal and oil boilers has been investigated. Different scenarios based on the power of the heat pump and the type of source (air or ground) have been simulated and compared economically and ecologically. Over the lifetime of the whole system, the levelized cost of heat for a combined heat pump & gas boiler heating system is lower than the reference case (coal & gas boilers). The installation of a heatpump covering at least 70% of the yearly heat demand would reduce the CO2-emission from minimum 70%.
Copyright (c) 2024 Matthieu Chaigneau, Björn Nienborg https://creativecommons.org/licenses/by/4.0
Optimizing Heat Pump Operation of Residential Buildings Using Calibrated R-C and Deep Learning Models and Electricity Costs Forecasts
The aim of this research is to improve the efficiency of energy systems using the mass of the building as thermal storage. We present a case study of a residential building, in which a detailed monitoring system was installed to measure, among other parameters, the electricity consumption, the indoor air quality, and the operation of the heating system, consisting on a Heat Pump (HP) and a radiant floor. Based on the data collected, both a lumped parameter model (R-C Model) and a Deep Learning (DL) Model have been calibrated to simulate the apartment analyzed. Both models provide a significantly accurate simulation of the apartment under real operating conditions. Then, using the simulation models, different operation scenarios have been analyzed. One of the scenarios considers the thermal inertia of the apartment and the electricity costs forecast to optimize the operation of the HP. Within this scenario, energy savings up to a 35.1%, and electricity costs savings up to a 47.3%, may be achieved during a winter season, when compared to the standardized operation of the HP.
Copyright (c) 2024 Pablo Hernandez-Cruz, César Escudero-Revilla, Moisés Cordeiro-Costas, Aitor Erkoreka-Gonzalez, Catalina Giraldo-Soto, Raquel Pérez-Orozco, Pablo Eguía-Oller https://creativecommons.org/licenses/by/4.0
Energetic Potential of Parallel Operation of Two Heat Sources in a Dual-Source Heat Pump
Dual-source heat pumps can mitigate disadvantages of single source heat pumps: They have fewer geological requirements compared to ground-source heat pumps while having higher efficiencies compared to air-source heat pumps. Parallel operation of two heat sources can also make electric heaters for peak loads obsolete, leading to economic benefits in the operational costs. Parallel operation has not been analysed thoroughly at different evaporation temperature gradients. To address this gap in research, four possible interconnections of two heat sources were analysed using a refrigerant cycle simulation, two with similar and two with separate evaporation pressures. The energetic potential of each interconnection is evaluated and compared to single source operation with an air-source and a ground-source heat pump. The results showed that only the interconnections with separate evaporation pressure allowed significant reduction in evaporation power from the ground source. As expected, the efficiency – compared to single air-source operation – increased for all parallel interconnections but decreased compared to ground-source operation. Efficient peak load coverage with small ground-source collectors therefore requires a more complex interconnection of completely split evaporator branches at different evaporation pressures. While the efficiency and heating power compared to single ground-source operation decreased slightly (by 4% and 6%, respectively), the power load on the GSHX and ASHX reduced to about 54% and 66% compared to the corresponding single-source operation, respectively. This allows high efficiency at reduced GSHX size and ASHX noise emission. Additionally, this interconnection also allows increased flexibility for improved heat source management.
Copyright (c) 2024 Tobias Reum, David Schmitt, Thorsten Summ, Tobias Schrag https://creativecommons.org/licenses/by/4.0
Techno-Economic Analysis of the Heating System Robustness
A techno-economic analysis of different heating systems of a multi-apartment building is performed. The final energy savings and the economic benefit under different boundary conditions are investigated for a Passive House that has been realized and monitored in Innsbruck, Austria. Eight different system combinations are considered, varying the heat generation (direct electric (as-built), air/water heat pump (HP) and groundwater HP) as well as the size of the photovoltaic (PV) system. The systems are investigated with a building model with two different parameterizations: the pre-design stage and the model adapted to the monitored boundary conditions (BC: climate and user behaviour) and monitored energy consumption. The monitoring of the first two years of operation revealed a significantly higher space heating demand (29 kWh/(m2a) compared to 8 kWh/(m2a)). The most robust system (i.e. the system that performs best independent of the BC) for primary energy optimization is identified as an air-source heat pump with a 32 kWp photovoltaic system. This system also allows economic savings in case of high heating demand (adapted building model) and slightly higher costs in case of low heating demand (pre-design model). The groundwater-source HP is cost-effective only in scenarios with high heating demand due to significant investment and installation costs. Monthly primary energy factors are used to account for seasonal effects of the energy demand, providing an assessment of system efficiency that accounts for the so-called winter gap.
Copyright (c) 2024 Elisa Venturi, Georgios Dermentzis, Mara Magni, Fabian Ochs https://creativecommons.org/licenses/by/4.0
3-Levers of Emission Control-Modeling Framework: Modeling GHG Emissions When Direct Measurement is not Possible
The Corporate Sustainability Reporting Directive (CSRD) requires the measurement and reporting of the greenhouse gas (GHG) emissions of companies and products in CO2-equivalent, considering all stages of their Life Cycle Assessment (LCA) where scopes 1, 2, and 3 emission categories are included. The GHG Protocol Product Life Cycle Accounting and Reporting Standard distinguishes between the “direct measurement” and ”indirect measurement”, i.e. activity-based measurement. The most accurate method would be to directly measure the GHG emissions. However, in many companies, this is not possible due to the unavailability of adequate measurement sensorics. For the activity-based LCA, the ISO14000 family of standards constructs an environmental management system by using a “technical” terminology. In contrast to that, the “E-Liability Accounting System” from Kaplan/Ramanna is casted in the language of financial and cost accounting. Accordingly, it presents the LCA of products GHG emission in a well-established and familiar theoretical foundation. The E-Liability Accounting System is constructed mainly at the conceptual level, as the activity-based GHG measurement and the distinction of scopes 1, 2, and 3 are not really operationalized. In this paper, these limitations are addressed by operationalizing the E-Liability Accounting System within the “3 Levers of Emission Control (3-LoEC)-modeling framework”. This framework allows the explicit specification of activity-based GHG measurement metrics all over the product’s life cycle. Due to the CSRD compliance, the 3-LoEC-modeling framework possesses practical validity. This carries over to its derived metrics. The applicability of the 3-LoEC-metrics is demonstrated in a use case, where a “food-bowl” is produced via injection molding technology.
Copyright (c) 2024 Lalla Hasnae Alaoui, Josef Baumüller, Walter S.A. Schwaiger https://creativecommons.org/licenses/by/4.0
Decarbonizing Process Heat Supply in the Austrian Pharmaceutical Industry
In the pharmaceutical industry, energy efficiency has played a minor role compared to other energy-intensive industries. However, there is a growing recognition of the need to address environmental concerns. With ambitious climate targets and the increasing demand for significant reductions in CO2 emissions, the pharmaceutical industry is now embracing the opportunity to enhance its sustainability practices. Mainly fossil fuels are used to provide process steam at moderate temperature levels at about 160-180°C and to a lesser extent to provide hot water or for on-site power production in CHPs. In this paper, the main processes with demands for process heat, such as media supply, cleaning, or air conditioning, are presented and possibilities for increasing efficiency, for switching to alternative heat supply and for using alternative process technologies are evaluated with respect to economics, but also regarding hurdles for implementation such as requirements for revalidation of production processes and possible necessity of re-approval of products. The present study highlights the potentials for decarbonization of the Austrian pharmaceutical industry using a generic but representative production site applying various measures that either reduce heating and cooling requirements or alter the temperature requirements for heat supply. It is shown that, at least for the example case, full decarbonization is technically feasibly without an increase in energy costs if efficiency measures are progressively used on demand level.
Copyright (c) 2024 Anton Beck, Matthias Traninger, Benedikt Mauel, Timo Kloska, Felix Hubmann, Daniela Leibetseder, Verena Sulzgruber, Nicolas Neubauer, Gerwin Drexler-Schmid https://creativecommons.org/licenses/by/4.0
Comparative Analysis of Solar Tower and Parabolic Trough Systems for Solar Heat in a Steel Industry
Concentrated Solar Thermal (CST) systems emerge as a promising alternative to replace fossil fuels used in industrial thermal processes due to their high energy density and dispatchability. In this study, a comparative analysis of two CST systems, Solar Tower (ST) and Parabolic Trough Collector (PTC), has been made to replace natural gas used in the steam generation process in Türkiye's largest steel production plant, located in the Mediterranean Region of Türkiye. Both the ST and PTC systems were placed in a field area of approximately 0.4 km2. The results have shown that, on a monthly basis, the PTC system could exceed the plant's thermal energy for two-thirds of the year, while the ST system could meet the plant's energy requirements for one-third of the year. This could reduce CO2 by about 12.7 and 19.1 kilo-tones for ST and PTC at LCOH of about 68.9 and 36.9 EUR/MWh, respectively.
Copyright (c) 2024 Deniz Değirmenci, Levent Güner, Onur Taylan, Didem Nedret İnceoğlu, Server Sakallı, Erdal Ünal https://creativecommons.org/licenses/by/4.0
Survey of Industrial Excess Heat Potentials in Austria
In the research and service study for the Energy Transition 2050 program, the technical excess heat potentials for both energy-intensive and energy-extensive Austrian industry were surveyed. A bottom-up approach for most of the energy-intensive industry and a top-down approach for most of the energy-extensive industry were used by the consortium under the leadership of the Chair of Energy Network Technology EVT of Montanuniversität Leoben. The surveyed potentials were classified according to temperature level of excess heat, origin from the process, spatial occurrence and industry sectors. In order to estimate the future industrial excess heat potentials, a database of the innovation network "New Energy for Industry" (NEFI) was used. For the geographical localization, the results were integrated into the existing Austrian Heat Map, which enables a comparison with heat demand densities and existing heating networks. A technical excess heat potential of about 34 TWh could be identified. Thereof, about 300 companies of the energy-intensive industry, which were mainly calculated by the bottom-up method, account for a technical excess heat potential of about 26 TWh. For the energy-extensive industry, an excess heat potential of about 4 TWh was identified for more than 1500 companies using mostly the statistical top-down method. Due to existing know-how in the consortium, the technical excess heat potentials of more than 600 sewage treatment plants could also be estimated at approx. 4 TWh.
Copyright (c) 2024 Andreas Hammer, Elisabeth Lachner, Thomas Kienberger, Wolfgang Gruber-Glatzl, Stefan Reuter, Marcus Hummel https://creativecommons.org/licenses/by/4.0
Tackling the Beast – How to Assess Scope 3 Emissions
The transparent and valid measurement of Scope 3 emissions (indirectly caused emissions upstream and downstream) represents one of the greatest challenges for companies during their sustainable transformation. In order to assess the current performance of a company and to derive the necessary action steps, it is essential to have the best possible knowledge of the current emissions. However, especially in the area of Scope 3, companies are dependent on external information and are not in a position to independently determine the ecological footprints of upstream purchased materials, products and services and the downstream emissions caused by products and services sold. This publication provides an overview of current main challenges and complexities deriving from the assessment of Scope 3 emissions and highlights the most suitable approaches to achieve best possible results.
Copyright (c) 2024 Lukas Höber, Anja Rotter, Michael Friedmann https://creativecommons.org/licenses/by/4.0
Scenario-Based Comparison of Sustainable Heating and Cooling Systems for Piglet Production Systems
Industrial pig farming is a highly energy-intensive activity due to the susceptibility of extensively bred pig breeds. To ensure efficient production, optimal climatic housing conditions are necessary. In this context, reducing CO2 emissions requires maximizing efficiency in heating and cooling provision, including a significant renewable energy component. However, pig farmers face a perpetual demand to refine their production methodologies due to evolving regulatory standards and market demands. This demand influences the efficacy of existing heating and cooling strategies. To address these challenges, a comprehensive case study was undertaken at a sizable piglet farm to devise a methodology that facilitates the projection of annual heating and cooling load profiles. This methodological framework is suitable for use in similar agricultural settings with comparable operational constraints. The proactive projection of heating and cooling load profiles constitutes a foundational step in evaluating potential heating and cooling systems with regard to their energy utilization, financial viability, and carbon footprint. Central to this evaluation are the comparative analyses of heating systems such as biogas and heat pumps, alongside cooling systems exemplified by compression chillers and absorption chillers.
Copyright (c) 2024 Konstantin König, Felix Pag, Klaus Vajen https://creativecommons.org/licenses/by/4.0
IT-Framework for Digital Energy Twin/Shadow Applications
Digital Energy Twins are IT systems, interconnecting sensor data, simulation models and user interfaces to formulate a virtual representation of the behavior of real energy systems. Digital Energy Twins are useful to predict the behavior of energy systems under varying boundary conditions and to optimize their operation considering economic and ecologic impact. Two different concepts of Digital Twins applicable to industrial energy systems were demonstrated: Digital Energy Twins and Digital Energy Shadows. While in literature, the term “Digital Twin” is widely used as synonym, for rather different applications involving simulations and virtual models connected to real-world data, this paper elaborates on the differences between digital twins and digital shadows in more detail. Given by the complexity of real-world energy systems (heat and electricity) and their implications on real time simulation, the concepts are demonstrated on different TRL levels. The results show the benefits and limitations of Digital Energy Twin and Digital Energy Shadow applications in relevant environments.
Copyright (c) 2024 Wolfgang Weiß, Carles Ribas-Tugores https://creativecommons.org/licenses/by/4.0
Integrated Sustainability Assessment of a Residential Heat Pump System
As there is currently a lack of reliable guidance for investors to make the most sustainable choice when it comes to different renewable heating technologies for residential buildings, this contribution presents a methodological approach for a comprehensive comparison, while also addressing data requirements. A focus point of the methodology development and the sustainability assessment lies on the integration of a dynamic electricity mix to account for the continuous decarbonization in an energy grid that is more and more based on renewables. Its influence on the final environmental impact results of the presented exemplary system combining a solar thermal collector and an air source heat pump is assessed. The results indicate a significant influence of the electricity mix on the carbon footprint (- 48%) of the provided heat. The resource use is only slightly changed (+ 3%).
Copyright (c) 2024 Marie Fischer, Sina Herceg, Karl-Anders Weiß https://creativecommons.org/licenses/by/4.0
Spatial Agent-Based Modelling and Simulation to Evaluate on Public Policies for Energy Transition
The manuscript describes the development of a spatial Agent-based Simulation to model the effect of public policies on private houseowner’s decisions concerning their heating system. The methodology utilized comprises of an empirical survey to determine the (location-based) behaviour and motivation of homeowners. In addition, spatial data on the houses can be used to implement renovation and thermal refurbishment in the simulation. In addition, the system is able to model and simulation the effect of public policies on the actions of homeowners. Hence, based on their decisions the system can estimate the carbon footprint of the houses over the simulation period. Hence, decision makers can select the best policy (e.g. funding, motivation) to reduce the carbon footprint of communities.
Copyright (c) 2024 Georg Weinberger, Simón Ladino Cano, Rizwan Bulbul, Franz Mauthner, Florian Korn, Joachim Ninaus, Maria Anna Hecher, Johannes Scholz https://creativecommons.org/licenses/by/4.0
Energy Savings, Environmental Impacts and Monitoring Results of a Pumped Solar Water Heating System at Katutura Hospital Maternity Ward, Namibia
The SADC region is endowed with solar radiation between 1800-2400 kWh/m2 [1]. Nevertheless only 0.3 % of the worldwide solar thermal capacity is installed in the Sab-Saharan African Countries. Therefore, the main goal of the Southern African Solar Renewable Heating and Cooling Initiative (SOLTRAIN+) project funded by the Austrian Development Agency is to contribute to the transformation of the energy system to a sustainable, affordable and carbon-free system. This will be done by the implementation of Renewable, Heating and Cooling (RHC) systems in the targeted sectors: buildings, industry & commerce, tourism and hospitals, and enable this by a holistic capacity building. RHC technologies are solar thermal, heat pump and energy efficiency. This study therefore intends to evaluate and produce energy balance, based on real data recorded from January 2023 to December 2023 on a 120 m2 collector area with 8000 litres storage tanks, and a 22 kW heat pump, installed at Katutura State Hospital maternity ward.
Copyright (c) 2024 Helvi Ileka, Joseph Shigwedha, Rudolf Moschik, Fenni Shidhika https://creativecommons.org/licenses/by/4.0
Life Cycle Assessment of Thermosyphon and PV Hot Water Systems Under the Same Operating Conditions in a Side-by-Side Experimental Setup in Namibia: Initial Results and Data Comparison with Existing Similar Installations
The global demand for hot water is increasing, driving a shift towards solar technologies. Namibia, aligning with emission reduction goals, plans to replace electric boilers with solar thermal and PV2Heat systems, emphasizing cost efficiency. This study focuses on providing eco-performance data for solar hot water systems, specifically thermosiphon and PV systems. Three systems in a container at the NUST Science and Technology Park are being compared, with commissioning scheduled for 2024. Preliminary eco-performance data will be derived from initial monitoring, followed by a comprehensive life cycle assessment (LCA). The study envisions a straightforward process in generating input data for the LCA, including performance data. Determining the levelized cost of electricity (LCOE) for economic comparison is a key aspect. While leveraging existing data from previous works, it acknowledges the limitations in estimating expected eco-performance indicators. The study aims for a direct LCA and eco-performance comparison between solar thermal and photovoltaic-based systems, contributing to Namibia's sustainable energy strategy.
Copyright (c) 2024 Harald Kicker, Gernot M. Wallner, Daniel Tschopp, Rudi Moschik, Wolfgang Gruber-Glatzl, Joseph Shigwedha, Helvi Ileka, Fenni Shidhika https://creativecommons.org/licenses/by/4.0
Analysing the Techno-Economic Viability of Different Solar Heating Systems in South African Beverage Plants
With ongoing real-term reductions in the cost of renewable energy technologies, opportunities to reduce carbon emissions within industry have improved. While the South African industrial sector has been investing in photovoltaics to meet electricity requirements, little has been done to replace fossil fuels used for the generation of process heat, representing two-thirds of the energy consumed. While previous studies have demonstrated the benefits and limitations of solar thermal (ST) energy solutions for industrial applications, recent developments in high-temperature heat pumps (HTHP) offer opportunities for novel configurations, including the use of renewable energy like photovoltaics (PV). This study compares the techno-economic benefits of solar thermal energy systems with PV-supported HTHP systems within the South African beverage sector. After a general consideration, simulation calculations are presented for selected applications. The cost of heat is determined for PV-heat pump systems operating on a stand-alone basis and with heat storage. The study finds that the levelised cost of heat of US$0.050-0.073/kWhth is at least twice that of coal-fired steam boilers. The study, therefore, calls for further work on optimising systems minimising steam requirements, and thereby improving the economics of heat pumps and for a coordinated effort to support the development and financing of high-temperature heat pumps for industrial applications.
Copyright (c) 2024 Johannes Koke, Francois Rozon, Craig McGregor https://creativecommons.org/licenses/by/4.0
An Outlook on the Adoption of Renewable Energy Solutions at South African Beverage Manufacturers
To decarbonise industry, which accounts for half of the total energy demand, renewable and sustainable energy solutions must be embraced. Not only to meet electricity requirements but, more importantly, to substitute fossil fuels used to generate process heat. This research assesses the cost-benefits of renewable and sustainable energy solutions for the South African beverage sector, representing an estimated 3020 GWh in annual energy demand, and provides a framework for the broader adoption of these technologies. For South African beverage producers, the study concludes that investments in photovoltaic and battery energy storage systems will continue to take priority, given the favourable 17–21 % Year-1 return on capital. However, given spatial and capital constraints, the judicious planning of solar thermal energy system requirements is advocated, to address the in-situ nature of process heat generation.
Copyright (c) 2024 Francois Rozon, Craig McGregor, Michael Owen https://creativecommons.org/licenses/by/4.0
Monitoring and Evaluation of Thermosyphon and PV Hot Water Systems Under the Same Operating Conditions in a Side-By-Side Experimental Setup
Renewable heating and cooling are the primary focus of the Southern African Renewable Heating and Cooling Training and Demonstration Initiative in creating capacity pertaining to this subject. This emphasis is aligned with the United Nation’s 2030 Agenda, which seeks for carbon-neutrality by the year 2030. To address thermal needs on small-scale, thermosiphons systems using evacuated tube collectors, flat-plate collectors, and photovoltaic to heat systems are frequently used. For a scale-up application of these technologies, and for accelerated achievement of carbon-neutrality, a cost-effective technology must be prioritised in various areas of the world with different meteorological conditions. This study therefore intends to establish the technical performance and the cost-effectiveness of these technologies in Namibia’s environment whilst replicating a small-scale house daily hot water demand.
Copyright (c) 2024 Joseph Shigwedha, Fenni Shidhika, Helvi Ileka, Daniel Tschopp, Rudolf Moschik, Penti Paulus https://creativecommons.org/licenses/by/4.0
Design and Economic Analysis of a Solar Thermal Pre-Cooling System for Agro-Cold Chain in Lesotho
The agricultural sector in Lesotho grapples with significant challenges regarding post-harvest losses. Given that 40% of all agricultural products require cold storage, food quality is compromised due to lack of cold storage to extract the heat from exposure to high field temperatures after harvest. This research proposes a solar thermal cooling system tailored to the specific needs of preserving fresh agricultural produce, leveraging Lesotho’s abundant solar energy resources. Through TRNSYS simulation and MATLAB economic analysis, optimal system parameters are determined, ensuring both technical efficiency and financial viability. The outcomes indicate that the proposed absorption solar thermal cooling system, incorporating evacuated tube collectors and an auxiliary boiler, effectively manages a cooling load of 7.318 kW, preserving fresh vegetables at 6.1°C. The optimized design features a chiller with a Coefficient of Performance of 0.8, a collector area of 12 m², and a hot storage volume of 0.2 m³, maximizing solar energy utilization. Importantly, economic metrics such as Levelized Cost of Energy ($0.085/kWh), Net Present Value ($9,200), Discounted Payback Period (12 years), and Savings to Investment Ratio (achieving 1 in year 13) demonstrate the financial feasibility and profitability of the system. These findings underscore the potential of solar thermal cooling as a promising investment option for addressing refrigeration needs in Lesotho, offering a sustainable solution to mitigate post-harvest losses and enhance economic performance in the agricultural sector.
Copyright (c) 2024 Mpho Yengane, Sebota Mokeke, Moeketsi Mpholo https://creativecommons.org/licenses/by/4.0