Integration of WtE and district cooling in existing Gas-CHP based district heating system – Central European city perspective

There are 1454 district heating systems in Germany. Most of them are fossil based and with high temperature levels, which is neither efficient nor sustainable and needs to be changed for reaching the 2050 climate goals. In this paper, we present a case study for transforming a high to low temperature district heating system which is more suitable for renewable energy supply. With the Carnot Toolbox, a dynamic model of a potential district heating system is simulated and then transformed to a low temperature supply. A sensitivity analysis is carried out to see the system performance in case space constrains restrict the transformation. Finally, an economic comparison is performed. Results show that it is technically possible to perform the transformation until a very low temperature system. The use of decentralized renewable sources, decentralized heat storage tanks and the placement of a heat pump on each building are the key points to achieve the transformation. Regarding the sensitivity analysis, the transformation is worth doing until the seasonal storage and solar collector field sizes are reduced to 60% and 80% of their values in the reference case, respectively. The economic analysis shows, however, that it is hard for highly efficient low temperature renewable based heat networks to compete with district heating systems based on a centralized fossile CHP solution. Thus, though the presented transformation is technically possible, there is a strong need to change existing economic schemes and policies for fostering a stronger promotion of renewable energy policies in the heat sector.

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District Heating System Flexibility Studies Using Thermal Inertia of Buildings

2020 IEEE 61th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) ◽

10.1109/rtucon51174.2020.9316600 ◽

2020 ◽

Author(s):

Jevgenijs Kozadajevs ◽

Dmitrijs Boreiko

Keyword(s):

Thermal Inertia ◽

District Heating ◽

Heating System ◽

District Heating System

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Predicting Hourly Heating Load in a District Heating System Based on a Hybrid CNN-LSTM Model

Energy and Buildings ◽

10.1016/j.enbuild.2021.110998 ◽

2021 ◽

pp. 110998

Author(s):

Jiancai Song ◽

Liyi Zhang ◽

Guixiang Xue ◽

YunPeng Ma ◽

Shan Gao ◽

...

Keyword(s):

District Heating ◽

Heating System ◽

District Heating System ◽

Heating Load

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Upgrading a District Heating System by Means of the Integration of Modular Heat Pumps, Geothermal Waters, and PVs for Resilient and Sustainable Urban Energy

Energies ◽

10.3390/en14092347 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2347

Author(s):

Elżbieta Hałaj ◽

Jarosław Kotyza ◽

Marek Hajto ◽

Grzegorz Pełka ◽

Wojciech Luboń ◽

...

Keyword(s):

District Heating ◽

Heating System ◽

Upper Jurassic ◽

Heat Pumps ◽

Water Levels ◽

Energy Potential ◽

Geothermal Waters ◽

District Heating System ◽

Heating And Cooling ◽

The City

Krakow has an extensive district heating network, which is approximately 900 km long. It is the second largest city in terms of the number of inhabitants in Poland, resulting in a high demand for energy—for both heating and cooling. The district heating of the city is based on coal. The paper presents the conception of using the available renewable sources to integrate them into the city’s heating system, increasing the flexibility of the system and its decentralization. An innovative solution of the use of hybrid, modular heat pumps with power dependent on the needs of customers in a given location and combining them with geothermal waters and photovoltaics is presented. The potential of deep geothermal waters is based on two reservoirs built of carbonate rocks, namely Devonian and Upper Jurassic, which mainly consist of dolomite and limestone. The theoretical potential of water intake equal to the nominal heating capacity of a geothermal installation is estimated at 3.3 and 2.0 MW, respectively. Shallow geothermal energy potential varies within the city, reflecting the complex geological structure of the city. Apart from typical borehole heat exchangers (BHEs), the shallower water levels may represent a significant potential source for both heating and cooling by means of water heat pumps. For the heating network, it has been proposed to use modular heat pumps with hybrid sources, which will allow for the flexible development of the network in places previously unavailable or unprofitable. In the case of balancing production and demand, a photovoltaic installation can be an effective and sufficient source of electricity that will cover the annual electricity demand generated by the heat pump installation, when it is used for both heating and cooling. The alternating demand of facilities for heating and cooling energy, caused by changes in the seasons, suggests potential for using seasonal cold and heat storage.

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Investigating energy performance of large-scale seasonal storage in the district heating system of chifeng city – measurements and model-based analysis of operation strategies

Energy and Buildings ◽

10.1016/j.enbuild.2021.111113 ◽

2021 ◽

pp. 111113

Author(s):

Luyi Xu ◽

Fang Guo ◽

Pieter-Jan Hoes ◽

Xudong Yang ◽

Jan L.M. Hensen

Keyword(s):

Large Scale ◽

District Heating ◽

Heating System ◽

Energy Performance ◽

District Heating System ◽

Model Based ◽

Model Based Analysis

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Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽

10.3390/en14113350 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3350

Author(s):

Theofanis Benakopoulos ◽

William Vergo ◽

Michele Tunzi ◽

Robbe Salenbien ◽

Svend Svendsen

Keyword(s):

Low Temperature ◽

Heat Loss ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Heating Power ◽

Circulation Loop ◽

Space Heating ◽

District Heating System ◽

Domestic Hot Water

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.

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