scholarly journals Optimal Design and Dispatch of Electrically Driven Heat Pumps and Chillers for a New Development Area

2020 ◽  
Vol 24 (3) ◽  
pp. 470-482
Author(s):  
Henrik Pieper ◽  
Torben Ommen ◽  
Brian Elmegaard ◽  
Anna Volkova ◽  
Wiebke Brix Markussen
Keyword(s):  
Heat Source ◽  
Optimization Model ◽  
Large Scale ◽  
District Heating ◽  
Heat Pumps ◽  
Mixed Integer ◽  
Heat Sources ◽  
Sources And Sinks ◽  
Heating And Cooling ◽  
New Development

AbstractLarge-scale heat pumps (HPs) and refrigeration plants are essential technologies to decarbonise the heating and cooling sector. District heating and cooling (DHC) can be supplied with low carbon footprint, if power generated from renewable energy sources is used. The simultaneous supply of DHC is often not considered in energy planning, nor the characteristics of the heat source and sink. Simplified approaches may not reveal the true potential of HPs and chillers. In this paper, different heat sources and sinks and their characteristics were considered for the simultaneous supply of DHC based on large-scale HPs and refrigeration plants. An optimization model was developed based on mixed-integer linear programming. The model is able to identify ideal production and storage capacities, heat sources and sinks based on realistic hourly operation profiles. By doing so, it is possible to identify the most economical or sustainable supply of DHC using electricity. The optimization model was applied to the Nordhavn area, a new development district of Copenhagen, Denmark. The results show that a combination of different heat sources and sinks is ideal for the case study. A HP that uses the district cooling network as a heat source to supply DHC was shown to be very efficient and economical. Groundwater and sewage water HPs were proposed for an economical supply of district heating. The Pareto frontier showed that a large reduction in annual CO2 emissions is possible for a relatively small increase in investments.

scholarly journals Large-Scale Geothermal Collector Systems for 5th Generation District Heating and Cooling Networks

2021 ◽  
Vol 13 (11) ◽  
pp. 6035
Author(s):  
Robin Zeh ◽  
Björn Ohlsen ◽  
David Philipp ◽  
David Bertermann ◽  
Tim Kotz ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Exchangers ◽  
Large Scale ◽  
Waste Heat ◽  
Freezing Point ◽  
Residential Buildings ◽  
District Heating ◽  
Solar Irradiation ◽  
Heat Sources ◽  
Heating And Cooling

Low temperature district heating and cooling networks (5GDHC) in combination with very shallow geothermal energy potentials enable the complete renewable heating and cooling supply of settlements up to entire city districts. With the help of 5GDHC, heating and cooling can be distributed at a low temperature level with almost no distribution losses and made useable to consumers via decentralized heat pumps (HP). Numerous renewable heat sources, from wastewater heat exchangers and low-temperature industrial waste heat to borehole heat exchangers and large-scale geothermal collector systems (LSC), can be used for these networks. The use of large-scale geothermal collector systems also offers the opportunity to shift heating and cooling loads seasonally, contributing to flexibility in the heating network. In addition, the soil can be cooled below freezing point due to the strong regeneration caused by the solar irradiation. Multilayer geothermal collector systems can be used to deliberately generate excessive cooling of individual areas in order to provide cooling energy for residential buildings, office complexes or industrial applications. Planning these systems requires expertise and understanding regarding the interaction of these technologies in the overall system. This paper provides a summary of experience in planning 5GDHC with large-scale geothermal collector systems as well as other renewable heat sources.

scholarly journals 5th generation district heating and cooling systems as a solution for renewable urban thermal energy supply

2019 ◽  
Vol 49 ◽  
pp. 129-136 ◽  
Author(s):  
Stef Boesten ◽  
Wilfried Ivens ◽  
Stefan C. Dekker ◽  
Herman Eijdems
Keyword(s):  
Large Scale ◽  
Fossil Fuel ◽  
Supply And Demand ◽  
District Heating ◽  
Thermal Storage ◽  
Energy System ◽  
Heat Pumps ◽  
Urban Environments ◽  
Cooling Systems ◽  
Heating And Cooling

Abstract. In order to reduce greenhouse gas emissions and decrease dependency on depleting fossil fuel resources the shift to a renewable energy system is necessary. District heating and cooling systems are a viable solution to provide heat and cold in urban environments. Renewable heat and cold sources that may get incorporated in future urban energy systems will not provide the same high temperature output as current fossil fuel fired systems. Fifth generation district heating and cooling (5GDHC) systems are decentralized, bi-directional, close to ground temperature networks that use direct exchange of warm and cold return flows and thermal storage to balance thermal demand as much as possible. 5GDHC offers a way to incorporate low temperature renewable heat sources including shallow geothermal energy, as well as reduce total demand by recuperating generated heat from cooling and generated cold from heating. The large scale of 5GDHC allows for optimal design of technical parts like heat pumps and thermal storage vessels, while increasing overall system efficiency by incorporating a large variety of supply and demand profiles. We provide a definition for 5GDHC and show how this concept differs from conventional district heating systems. The Mijnwater system in Heerlen, the Netherlands is showing what a city-level 5GDHC system can look like.

scholarly journals 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 ◽  
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.

scholarly journals Evaluating the Potential Contribution of District Heating to the Flexibility of the Future Italian Power System

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 584
Author(s):  
Chiara Magni ◽  
Sylvain Quoilin ◽  
Alessia Arteconi
Keyword(s):  
Power Systems ◽  
Power System ◽  
Large Scale ◽  
District Heating ◽  
Energy System ◽  
Heat Pumps ◽  
Electricity Sector ◽  
Potential Contribution ◽  
The Future ◽  
Promising Solution

Flexibility is crucial to enable the penetration of high shares of renewables in the power system while ensuring the security and affordability of the electricity dispatch. In this regard, heat–electricity sector coupling technologies are considered a promising solution for the integration of flexible devices such as thermal storage units and heat pumps. The deployment of these devices would also enable the decarbonization of the heating sector, responsible for around half of the energy consumption in the EU, of which 75% is currently supplied by fossil fuels. This paper investigates in which measure the diffusion of district heating (DH) coupled with thermal energy storage (TES) units can contribute to the overall system flexibility and to the provision of operating reserves for energy systems with high renewable penetration. The deployment of two different DH supply technologies, namely combined heat and power units (CHP) and large-scale heat pumps (P2HT), is modeled and compared in terms of performance. The case study analyzed is the future Italian energy system, which is simulated through the unit commitment and optimal dispatch model Dispa-SET. Results show that DH coupled with heat pumps and CHP units could enable both costs and emissions related to the heat–electricity sector to be reduced by up to 50%. DH systems also proved to be a promising solution to grant the flexibility and resilience of power systems with high shares of renewables by significantly reducing the curtailment of renewables and cost-optimally providing up to 15% of the total upward reserve requirements.

scholarly journals Large-Scale Pumped Thermal Electricity Storages—Converting Energy Using Shallow Lined Rock Caverns, Carbon Dioxide and Underground Pumped-Hydro

2019 ◽  
Vol 9 (19) ◽  
pp. 4150 ◽  
Author(s):  
Pascal Lalanne ◽  
Paul Byrne
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
District Heating ◽  
Energy Transition ◽  
Heating And Cooling ◽  
Long Duration ◽  
Low Emission ◽  
Rock Cavern ◽  
Lined Rock Cavern ◽  
Thermal Stores

A fast-paced energy transition needs a higher penetration of renewables, of heating and cooling in the worldwide energy mix. With three novelties 1-of using shallow high-pressure LRC (Lined Rock Cavern) excavated close to storage needs, 2-of using a slow-moving CO2 piston applying steady pressure on the hydro part of UPHES (Underground Pumped Hydro Energy Storage) and 3-of relying on inexpensive thermal stores for long-duration storage, CO2 UPHES coupled with PTES (Pumped Thermal Electricity Storage) could become, at expected Capex cost of only 20 USD/kWh electrical, a game-changer by allowing the complete integration of intermittent renewable sources. Moreover, even though this early conceptual work requires validation by simulation and experimentation, CO2 UPHES as well as UPHES-PTES hybrid storage could also allow a low-cost and low-emission integration of intermittent renewables with future district heating and cooling networks.

Mixed-integer nonlinear optimization for district heating network expansion

2020 ◽  
Vol 68 (12) ◽  
pp. 985-1000
Author(s):  
Marius Roland ◽  
Martin Schmidt
Keyword(s):  
Nonlinear Optimization ◽  
Optimization Model ◽  
Thermal Effects ◽  
Nonlinear Models ◽  
Valid Inequalities ◽  
Average Power ◽  
District Heating ◽  
Mixed Integer ◽  
Mixed Integer Nonlinear Optimization

AbstractWe present a mixed-integer nonlinear optimization model for computing the optimal expansion of an existing tree-shaped district heating network given a number of potential new consumers. To this end, we state a stationary and nonlinear model of all hydraulic and thermal effects in the pipeline network as well as nonlinear models for consumers and the network’s depot. For the former, we consider the Euler momentum and the thermal energy equation. The thermal aspects are especially challenging. Here, we develop a novel polynomial approximation that we use in the optimization model. The expansion decisions are modeled by binary variables for which we derive additional valid inequalities that greatly help to solve the highly challenging problem. Finally, we present a case study in which we identify three major aspects that strongly influence investment decisions: the estimated average power demand of potentially new consumers, the distance between the existing network and the new consumers, and thermal losses in the network.

scholarly journals Longevity and power density of intermediate-to-deep geothermal wells in district heating applications

2021 ◽  
Vol 136 (1) ◽  
Author(s):  
Eero Hirvijoki ◽  
David Pfefferlé ◽  
Manasvi Lingam
Keyword(s):  
Heat Transfer ◽  
Power Density ◽  
Large Scale ◽  
Hot Spot ◽  
District Heating ◽  
Heat Sources ◽  
Heating Systems ◽  
District Heating Systems ◽  
Geothermal Wells ◽  
The City

AbstractThis paper assesses the potential of intermediate-to-deep geothermal wells for district heating purposes in non-hot spot regions as a means for replacing carbon-intensive heat sources. In analysing the problem of heat transfer from the bedrock to a flowing coolant in the well, we perform parameter scans to assess the longevity and power density of different-size wells and derive analytical estimates to explain salient characteristics of the well behaviour. The results are then utilized to illustrate how intermediate-to-deep geothermal wells would compare with the requirements of typical large-scale district heating systems, by using the city of Helsinki in Finland as an example.

scholarly journals Investigation on Relative Heat Losses and Gains of Heating and Cooling Networks

2021 ◽  
Vol 25 (1) ◽  
pp. 479-490
Author(s):  
Violeta Madan ◽  
Ingo Weidlich
Keyword(s):  
District Heating ◽  
Energy System ◽  
Heat Losses ◽  
Heat Sources ◽  
Temperature Level ◽  
Near Surface ◽  
Heating And Cooling ◽  
Surface Soil Temperature ◽  
Steady State Heat ◽  
Sustainable Energy System

Abstract The integration of district heating (DH) and cooling (DC) in the sustainable energy system of the future requires a significant reduction in operating temperatures. Supply temperatures below 70 °C are required for new 4th Generation DH. Main benefits are the use of low exergy heat sources and the reduction of heat losses. The reduction of heat losses is achieved by reducing the driving temperature difference between the medium pipe and the ground. The decrease of the return temperature level is limited by the consumer behaviour and the ground temperature level. As a consequence, the reduction of the supply temperature is accompanied by a reduction of the maximum transmittable heat flow. For energy efficiency and economic reasons, the relative heat losses are therefore an important design value for DH networks. The study proposes an approach to estimate the relative heat losses by using steady-state heat loss models and analyses the values for different DH generations. In particular, due to the rising of the near-surface soil temperature, the relative cold losses are also studied.

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