Cogeneration unit with an absorption heat pump for the district heating system

Absorption heat pumps can lift a lower temperature waste heat source to a higher temperature useful output. In that process, it uses less electricity as an input compared to heat pumps with electrical compressors. Therefore, in some cases, it can be used to lift a lower temperature waste heat source to a higher temperature useful output with less electricity consumption. Absorption heat pumps are not very widely spread in district heating, mostly because there aren’t many suitable waste heat sources or conditions needed to run them. Tallinn has a district heating system with an annual generation of more than 2 TWh and a goal to make it an entirely carbon neutral district heating system by 2030. Tallinn has also started to develop a district cooling network, and by the end of 2023, the installed capacity was about 6 MW. District cooling capacity is estimated to grow to around 100 MW in 2030. This paper investigates different types of absorption heat pumps and the possibilities of integrating an absorption heat pump to a district cooling plant with the purpose of using waste heat from the cooling plant for renewable heat generation, that can be used in district heating. Different technical aspects are examined to find a suitable production solution, are presented as results. From an economical point of view, the cost of heat to cover peaks with an absorption heat pump is calculated. The effect of reducing fossil fuel use in the Tallinn district heating network with an absorption heat pump is estimated.

Dynamic response of gravity-driven flow in multi-section absorption heat pump

The combined production of electricity and thermal energy (combined heat and power or co-generation) is the most efficient and convenient approach to reduce costs for energy at industrial power plants and district heating plants that use natural gas as fuel to produce thermal energy for various needs. This paper analyses the operational characteristics of the combined heat and power plant, which has been operating since January 1, 2021, at the Vozdovac Heating Plant as part of the Belgrade district heating system. The combined heat and power plant consists of three gas engine units with a total nominal electric power of 10 MW and thermal power of 10.1 MW, which use natural gas as fuel. The combined heat and power plant is used for district heating and preparing domestic hot water while electricity is sold to the local electric grid. The analysis in this paper focuses on the plant?s operational characteristics: the number of working hours, the total energy consumption and energy production, the efficiency as well as the operational and maintenance costs. Also, the impact of the drastic changes in the prices of natural gas, electricity, and maintenance costs in the last year on the financial profitability of the combined heat and power plant was analysed in particular.

A new waste heat district heating system with combined heat and power (CHP) based on ejector heat exchangers and absorption heat pumps

Metamorphoses of cogeneration-based district heating in Romania: A case study

Analysis of the distribution of CO2 concentrations was performed for a water-and-steam boiler plant located in a detached building supplying thermal energy to a hospital. The boiler plant was equipped with two low-temperature boilers and one high-temperature steam boiler. The maximum thermal energy demand of the hospital was 4280, 3500 kW of which came from the hot-water boilers and the remaining 780 kW from the steam boiler. Due to the operating system there were no permanent job positions in the boiler plant. Servicing consisted only in the supervision, periodic adjustment and maintenance of the equipment. These kinds of working conditions release the employer from the necessity to perform tests and measurements of working conditions in such a building. On the other hand, continuous measurements are made because of the installation safety and emissions of pollutants into the environment. The article presents results of the measurements and analysis of the distribution of CO2 concentrations inside and outside a small boiler plant, due to which it was found that the level of carbon dioxide concentration did not depend on the ambient air temperature. The resulting values are similar regardless of whether the measurements were taken in December 2012 or April 2013. However, there is an evident impact of seasons on the concentrations in the indoor air associated primarily with the demand for heat during the given period, the stay of people in the workplace and the number of working devices.

In order to decrease the energy consumption of large-scale district heating systems with cogeneration, a district heating system is presented in this paper based on absorption heat exchange in the cogeneration system named Co-ah cycle, which means that the cogeneration system is based on absorption heat exchange. In substations of the heating system, the temperature of return water of primary heat network is reduced to about 25°C through the absorption heat-exchange units. In the thermal station of the cogeneration plant, return water is heated orderly by the exhaust steam in the condenser, the absorption heat pumps, and the peak load heater. Compared with traditional heating systems, this system runs with a greater circuit temperature drop so that the delivery capacity of the heat network increases dramatically. Moreover, by recovering the exhausted heat from the condensers, the capacity of the district heating system and the energy efficiency of the combined heat and power system (CHP system) are highly developed. Therefore, high energy and economic efficiency can be obtained.

Thermodynamic performance analysis and modified thermo-ecological cost optimization of a hybrid district heating system considering energy levels

District heating (DH) is a proven heat generation and distribution technology that enhances energy efficiency and reduces carbon emissions at scale, making it a key component of sustainable energy strategies. Compared to traditional heat generation methods such as using onsite fossil-fuelled combustion boilers or electrically driven heating systems, DH offers superior environmental advantages, particularly when renewable energy and waste heat are deployed as primary fuel energy mix. To comprehensively evaluate the sustainability of DH, life cycle assessment (LCA) is widely adopted to determine environmental impacts across all life cycle stages, from material extraction to disposal. This systematic review identifies the absence of a unified, adaptable framework for LCA application in DH systems. To address this, the study proposes a structured multi-level framework, interpreting methodological diversity across component, facility, and network levels. Component-level studies offer insights into specific technologies and materials; facility-level assessments focus on operational performance and energy sources; network-level evaluations provide holistic system impacts. Aligning studies within these analytical levels enables fairer comparisons, supports cross-regional learning, and promotes methodological integration. Recurring challenges include inconsistent methodologies, varying system boundaries, and limited local data. Emerging technologies such as hybrid systems, smart grids, and energy storage remain underrepresented in LCA studies. Tools like SimaPro, GaBi, and OpenLCA are widely used, yet the rapid evolution of DH systems calls for more tailored applications. This review supports the development of standardised, yet flexible LCA practices and proposes a refined multi-level framework to guide comprehensive, context-specific evaluations. It emphasises the importance of validating approaches across diverse contexts and strengthening LCA’s contribution to the design of sustainable, low-carbon DH solutions for urban energy systems. Multi-level LCA approach categorises DH systems into component, facility, and network levels. Current LCA research on DH systems focuses on Europe, with gaps in Asia and the US. Tools like SimaPro, GaBi, and OpenLCA support detailed LCA analyses of district heating. LCA for DH systems faces challenges like data gaps, system boundaries, and variability. The proposed workflow enables tailored, actionable LCA assessments for diverse DH systems.

Comparative Analysis Between District Heating and Geothermal Heat Pump System

Local or district heating by natural gas: Which is better from energetic, environmental and economic point of views?

As the world’s energy needs rise, carbon emissions and climate change become a bigger concern. Therefore, there is a growing need for cleaner energy sources as well as higher levels of energy efficiency. Building energy is of great interest to researchers and policymakers, as it accounts for about a third of global energy consumption, and this is projected to rise as more people gain access to higher incomes and improved amenities. For over a century, district energy systems have proved to be an efficient means of providing thermal energy to buildings, and developments in district heating have enabled the use of various heat sources, including low-temperature sources, such as waste heat. Waste heat is a viable and technically mature source of building energy, as proven by many operational cases, but there seem to be only a few sources of waste heat utilized in practice or explored in literature. Additionally, many research studies focus on only one source of waste heat for district heating and, to the knowledge of the authors, there is currently no existing review paper on the various sources of waste heat utilized in district heating. Therefore, the goal of this paper is to examine various sources of waste heat that are utilized in real operational district heating cases or discussed in research studies. Additionally, the paper discusses the various performance metrics utilized for quantifying waste heat potential in existing literature, and rounds off with recommended future study. • Waste heat integration can raise district heating and building energy efficiency and resilience. • Various sources of waste heat utilized in district heating systems are reviewed and compared. • Performance metrics for waste heat integration are reviewed, and an ideal metric is defined.

District heating system with power generation is integrated in the electricity system since combined heat and power (CHP) plants are used for heat supply. Nowadays, the changes happen in the electricity system and conventional CHP plant operation. They are caused by wide integration of renewable energy sources (RES) in energy production process, feed-in tariffs for RES, the implementation of market mechanisms, and the incremented requirement in energy efficiency and flexibility of power plants. This creates new opportunities and conditions for district heating (DH) and power system cooperation though the use of DH flexible technologies, i.e., power-to-heat (P2H) technologies (electric boilers (EB) and heat pumps). The use of P2H technologies is limited and they are not costs-efficient due to electricity tariff formed components. Two Targets of EB use at power plant are evaluated, omitting these components, to show the usefulness and significant of these technologies for conventional generation.

This paper aims to illustrate a new holistic modeling environment through a case study implementing a district heating system to supply four groups of users identified in the city of Tokyo. The holistic modeling environment, called DOME (Distributed Object-based Modeling Environment) is being used by researchers in the Alliance for Global Sustainability (AGS) to develop a platform for assessing technologies and policies in order to significantly reduce CO2 emissions in large cities. DOME is used as an information based collaboration platform for supporting the decentralized integration of models built independently under various application tools and operating systems. It provides system engineers with the ability to access experts’ models over the Internet through user-friendly interfaces. The interfaces provide clearly identified input and output variables to support a facilitated integration. The DOME environment also provides tools for analyzing the resultant integrated system. In this district heating simulation, a GIS (geographic information system) based land-use database manager, implemented as an object in DOME, is used to obtain the total ground area, the total building floor area, and the number and type of buildings in a specified region of Tokyo. Using the land use database manager, four groups of users are established. The heat demands of the users are derived using specific heat consumption data for the types of buildings considered. Users are either connected to the district heating system through direct heat exchangers on the supply or return line, or through local heat pumps which adapt the temperature to the needs locally, allowing a lower network temperature. Two different options are considered for the district heat supply: 1) a heat pump based superstructure comprising a gas turbine and a gas engine as cogeneration units, as well as an auxiliary boiler for peak load, and 2) a gas turbine / steam turbine combined cycle based superstructure with various options like steam injection and/or CO2 separation unit. Physical and costing models for the two alternative production unit superstructures and for the district heating system are connected with the GIS database manager using DOME. The environomic methodology, a simultaneous consideration of thermodynamic, economic and environmental criteria expressed as an aggregated cost, is used to assess the alternatives under different scenarios characterized by the cost of natural gas and the degree of pollution cost internalization.

This research assesses the potential of a mobile thermochemical storage system, the mobile heat battery (M-HB), for decarbonizing a low-temperature district heating (DH) system in the Netherlands. The assessment is built on a case study where the M-HB is used to transport waste heat from different sources to a neighborhood interface of a DH system. This case study utilizes a simulation-based methodology to calculate the emissions from grid electricity, DH, and M-HB transport and charging. Building performance simulation is used as the main experimental method in combination with both empirical data and theoretical assumptions. Various system operational strategies and uncertain factors are explored, and waste heat sources are screened by different decarbonization targets. Findings indicate that using the M-HB can reduce the operational carbon emissions by up to 80 %, from approximately 60–70 KgCO2/GJ of the system without M-HB to around 13 KgCO2/GJ in optimal scenarios. Emissions from M-HB transport and charging are identified as more influential to the decarbonization potential than other considered factors, which addresses the significance of choosing proper waste heat sources. Despite some limitations from data availability and assumptions, this work identifies both opportunities and challenges for using M-HB to decarbonize DH systems.