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The planning of energy infrastructures in new districts often follows the practice adopted for the rest of the city. In Stockholm, district heating is a common solution for multi-apartment neighborhoods. Recently, because of an average clean electricity mix, heat pumps have gained interest. However, European studies suggest to limit the reliance on...
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... o u r n a l P r e -p r o o f Over one year, the cables that are found overloaded are thus Cable 1, Cable 2, Cable 3, Cable 4 and Cable 5. These are highlighted in red in the electricity distribution grid topology in Figure 8. This figure further helps to point out the relation between the cables and the connected BBs, and thus the dsHPs. ...
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The continuous rise of global carbon emissions demands the utilization of fossil fuels in a sustainable way. Owing to various forms of emissions, our environment conditions might be affected, necessitating more focus of scientists and researchers to upgrade oil processing to more efficient manner. Gasification is a potential technology that can con...
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... These studies show how site-specific conditions, the energy performance of the buildings, the use of the buildings, the district heating temperature, and heat losses in the district heating network strongly influence technical and economic indicators [79][80][81]. The energy supply scenario assessments provide insights into how traditional district heating systems can be transformed towards the fourth and fifth generation of district heating by including distributed heat pumps, prosumers in district heating networks, and different supply technologies for district heating [82][83][84]. The studies highlight the potential of heat pump technologies including cooling [82] and lower district heating temperatures through e.g., the recovery of excess heat which is largely available [80,83,84]. ...
... The energy supply scenario assessments provide insights into how traditional district heating systems can be transformed towards the fourth and fifth generation of district heating by including distributed heat pumps, prosumers in district heating networks, and different supply technologies for district heating [82][83][84]. The studies highlight the potential of heat pump technologies including cooling [82] and lower district heating temperatures through e.g., the recovery of excess heat which is largely available [80,83,84]. The economic assessments demonstrate that distributed heat pumps have a higher levelized cost of heating than district heating alternatives, mainly because of the investment costs [82,83], while heating systems with waste heat recovery can lower the levelized cost of heating [83]. ...
... The studies highlight the potential of heat pump technologies including cooling [82] and lower district heating temperatures through e.g., the recovery of excess heat which is largely available [80,83,84]. The economic assessments demonstrate that distributed heat pumps have a higher levelized cost of heating than district heating alternatives, mainly because of the investment costs [82,83], while heating systems with waste heat recovery can lower the levelized cost of heating [83]. Large-scale heat pumps also prove to be more cost-efficient due to economies of scale [82]. ...
Over the past 30 years, several sustainability-profiled districts have been developed in Sweden with high ambitions for the energy systems, such as Hammarby Sjöstad in Stockholm and Western Harbor in Malmö. Research into energy systems in urban districts is interdisciplinary and therefore spread over different areas, which means that an overview of the current state of knowledge and lessons learned is lacking. This semi-systematic literature review aims to provide an overview of previous research on the planning, development, and evaluation of energy systems in sustainability-profiled districts in Sweden. The review of 70 journal and conference articles reveals seven research themes in the interdisciplinary nexus of energy systems and sustainability-profiled districts: (1) Conceptualizations and critique of sustainability-profiled districts, (2) Evaluations of energy goals and requirements , (3) Technical and economic assessments of heating and electricity systems, (4) Integration of innovative (energy) solutions in urban planning, (5) Stakeholder perspectives on energy systems, (6) Stakeholder collaboration on the building and the district level, (7) Governance and policy instruments for sustainable urban development and energy systems. We use a socio-technical ecology approach to critically discuss the existing research on energy systems planning, development, and evaluation to guide future research on energy systems development in urban districts. An increase in integrated approaches across all identified research themes and relationships between scales, phases, and impacts are discussed as central observations that can guide future research. Future research is needed on new or better-adapted energy indicators, the inclusion, perspectives, and roles of (new) stakeholders, and the consideration of ecology and nature in research on the planning, development , and evaluation of energy systems.
... Predicted decrease in heat pump application due to larger incentives for CHP and waste incineration [36] Utilising thermal energy storage, allowing for flexibility to avoid peak demands, reducing the likelihood of overwhelming the electrical infrastructure and improving energy costs [37] Utilising heated return waters in district cooling systems to be used as a heat source in large heat pumps supplying heat into DH systems [20] Simultaneous heating and cooling synergies which benefits from reduced energy consumption [38] Propane refrigerant (R-290) is a viable alternative, when swapped for R-134a, the overall climate change impact for generating 1 kWh of heat becomes negative at -0.009 kgCO 2 eq/kWh in comparison to 0.008 kgCO 2 eq/kWh for R-134a in a 2050 scenario [40] Europe case study presents heat pump integration flexibility by recovering heat from sources such as sewage water, industrial waste heat, geothermal water, flue gas and solar heat storage [41] industries has a great potential in curbing CO 2 emissions. This is supported by Arnaudo et al. [43] who state that waste heat recovery at 10% of the peak load can reduce fossil fuels by 40%. A study in the UK shows that if the re-used waste heat from its buildings and industrial processers, this could be used to supply 14% of the hot water and heating demand in UK homes [44]; when directly comparing this to the results of Arnaudo et al. [43], this would indicate that a possible over 40% fossil fuel reduction could be achieved. ...
... This is supported by Arnaudo et al. [43] who state that waste heat recovery at 10% of the peak load can reduce fossil fuels by 40%. A study in the UK shows that if the re-used waste heat from its buildings and industrial processers, this could be used to supply 14% of the hot water and heating demand in UK homes [44]; when directly comparing this to the results of Arnaudo et al. [43], this would indicate that a possible over 40% fossil fuel reduction could be achieved. Most recently, Hancox et al. [45] revealed the viability of harnessing waste heat from the hot smoke through a cold abatement smoke extract system over the course of industrial manufacturing in the UK. ...
... Waste heat recovery at 10% of the peak load can reduce fossil fuels by 40% [43] It is viable to harness waste heat from the hot smoke through a cold abatement smoke extract system over the course of industrial manufacturing in the UK [45] Heat recovery from industrial surplus, incineration plants and energy plants could solely supply low energy buildings if stability was maintained [33] Case study showed a steam generator's exhaust gas increased the heating capacity of the system by 41%; this was achieved by heat transfer through an ejector heat exchanger based on the ejector refrigeration cycle [46] Case study presents some of the world's largest DH networks which utilise heat pumps often rely on the likes of sewage water, ambient water and industrial heat as a main resource, while sewage water was revealed the most resilient source [49] Case studies show adverse effects caused by prosumers' lower temperatures being supplied into the network, causing an overall decrease in the network's operating temperature [50,51] highest importance (32.3%) was given to the impact on customers. This was due to the large quantity of low energy efficient buildings, which had a higher risk of dissatisfactory thermal comfort due to the lower supply temperatures. ...
The UK is currently approaching a critical point in the fight against climate change. To achieve carbon neutral by 2050, it is crucial that the way in which buildings are heated are reviewed to determine the most suitable solution. The UK government has acknowledged that district heating (also referred to as heat networks) forms an important part of their plan for future sustainability in heating homes as well as improving energy costs. At present, there are five generations of district heating with distinctive improvements between each. However, research shows a lack of progression with only minor improvements to efficiencies and carbon emissions in the past two decades. Therefore, this paper aimed to review the key technologies and design principles of the low-impact network which shall be implemented into future networks to ensure sustainability and carbon neutral. Furthermore, data were utilised from UK government's ‘Heat Network Project Pipeline’ documents which cover a wide range of projects supported through the development stage by the UK Heat Network Delivery Unit. A statistical analysis was also undertaken to identify popular heat source technologies currently being implemented into the UK networks. Information such as technologies, size and costs were analysed to establish the intercorrelations, which may influence the type of technologies being selected. The results show that 56% of total networks contained Combined Heat and Power (CHP) as a primary heat source, of which over 40% were gas fired CHP, displaying the current dominance of the technology. Overall, it is evident in the UK that, the new networks have been improved from previous generations with a high concentration of renewable energy technologies and heat recovery methods being used. However, there is still a high reliance on natural gas, which does not fulfil the characteristics of a low-impact heating network.
... A study [11] proposes using waste heat recovery in low-temperature DH networks as an alternative to a domestic heat pump, which has gained interest recently. The authors perform a techno-economic and environmental analysis of the alternatives for the planning of heating of urban neighborhoods considering Nordic conditions. ...
... The instantaneous exergy efficiency (ζ(t)) is defined as the ratio of the exergy flow rate, absorbed by the LHS (Ex store (t)) to the exergy flow rate, collected by the solar collector (Ex c (t)), as shown in Equation (11). Equation (12) presents the average exergy storage efficiency, which is defined as the ratio of the exergy absorbed by the LHS to the exergy collected by the solar collector over the specified period of time. ...
... Ex store (t) Ex c (t) (11) ...
The current interest in thermal energy storage is connected with increasing the efficiency of conventional fuel-dependent systems by storing the waste heat in low consumption periods, as well as with harvesting renewable energy sources with intermittent character. Many of the studies are directed towards compact solutions requiring less space than the commonly used hot water tanks. This is especially important for small capacity thermal systems in buildings, in family houses or small communities. There are many examples of thermal energy storage (TES) in the literature using the latent heat of phase change, but only a few are commercially available. There are no distinct generally accepted requirements for such TES systems. The present work fills that gap on the basis of the state of the art in the field. It reviews the most prospective designs among the available compact latent heat storage (LHS) systems in residential applications for hot water, heating and cooling and the methods for their investigation and optimization. It indicates the important characteristics of the most cost- and energy-efficient compact design of an LHS for waste heat utilization. The proper design provides the chosen targets at a reasonable cost, with a high heat transfer rate and effective insulation. It allows connection to multiple heat sources, coupling with a heat pump and integration into existing technologies and expected future scenarios for residential heating and cooling. Compact shell-tube type is distinguished for its advantages and commercial application.
... Regarding the 2015 Paris Agreement, the urgency of the climate change challenge is highlighted [4], trying to keep the global temperature increase below 2 °C by reducing CO2 production [5]. Therefore, several countries worldwide have adopted ambitious targets to reduce their carbon footprint [4]. ...
... Regarding the 2015 Paris Agreement, the urgency of the climate change challenge is highlighted [4], trying to keep the global temperature increase below 2 °C by reducing CO2 production [5]. Therefore, several countries worldwide have adopted ambitious targets to reduce their carbon footprint [4]. An alternative is using a sustainable energy system, which implies achieving adequate energy efficiency and the potential use of renewable energies; both can achieve industrial development while maintaining care for the environment and social welfare [6]. ...
... As mentioned above, the MAHP needs four energy levels to function correctly. First, the high-temperature thermal source (between 100 and 160 °C [39,40]) has the enormous potential of using various power sources, such as solar energy with evacuated tube collectors or concentration systems [13][14][15][16], biomass [17][18][19], geothermal energy [20,21], or industrial waste heat [1,3,4]. The medium-temperature thermal source (60-100 °C [39,40]) has excellent versatility in using different energy sources due to its low and easily attainable temperature range [12]. ...
The novel modified absorption heat pump (MAHP) with the H2O-LiBr working mixture for cogeneration applications is introduced. The MAHP can simultaneously produce electric energy and heat revaluation. The proposed system has the particularity that it can be powered by alternative thermal sources (such as solar energy, biomass, geothermal) or industrial waste heat, thus promoting the production and efficient use of clean energy. The effects of pressure ratio (RP), source or supply temperature (TGH), and the energy revaluation gradient (GTL) are analyzed. The critical parameters of the proposed system are evaluated, including thermal efficiency (η Th), exergetic efficiency (η Ex), revaluated heat (Q̇A), as well as net power produced (Ẇ net). For the MAHP analysis, RP and TGH operating ranges were chosen at 1.1-15.0 and 100-160 °C, respectively. The results show that η Ex of 87% can be obtained, having the maximum performance in TGH of 120 °C, RP of 1.1, and GTL of 35 °C. The η Th varies between 51% and 55%, having a maximum GTL of 45 °C. On the other hand, Ẇ net achieves values between 260 and 582 kW, depending on the defined operating conditions.
... Waste can be integrated into the energy system in the form of energy recovery processes, such as incineration and anaerobic digestion [8,10,11]. The implementation of waste in sector coupling has a direct effect on energy infrastructure planning, as reported by Arnaudo et al. [63]. However, Puttachai et al. [64] have found that there is no consistent conclusion on the effect of waste-to-energy on other energy system operations yet. ...
Decentralisation and sector coupling are becoming increasingly crucial for the decarbonisation of the energy system. Resources such as waste and water have high energy recovery potential and are required as inputs for various conversion technologies; however, waste and water have not yet been considered in sector coupling approaches but only in separate examinations. In this work, an open-source sector coupling optimisation model considering all of these resources and their utilisation is developed and applied in a test-bed in an Israeli city. Our investigations include an impact assessment of energy recovery and resource utilisation in the transition to a hydrogen economy, with regard to the inclusion of greywater and consideration of emissions. Additionally, sensitivity analyses are performed in order to assess the complexity level of energy recovery. The results demonstrate that waste and water energy recovery can provide high contributions to energy generation. Furthermore, greywater use can be vital to cover the water demands in scarcity periods, thus saving potable water and enabling the use of technology. Regarding the transition to hydrogen technologies, resource energy recovery and management have an even higher effect than in the original setup. However, without appropriate resource management, a reduction in emissions cannot be achieved. Furthermore, the sensitivity analyses indicate the existence of complex relationships between energy recovery technologies and other energy system operations
... The technoeconomic analysis of recovering waste heat from low temperature district heating networks and comparison with domestic heat pump was investigated. It was observed that the local grid limitation holds up the viability of domestic heat pump [67]. ...
... Waste heat recovery from district heating reduced the dependence of fossil fuel by 40% and also reduced the CO 2 emission by 6%. Besides, domestic scale heat pump increased the emission of CO 2 by 11% [67]. Recovery of LTWH from combined heat and power unit of energy intensive unit was studied. ...
Utilization of unused waste heat energy below 100 °C is a challenging effort. In spite of investing in energy retrieving technology, a considerable amount of heat energy is still dissipating to the surroundings. The recovery of LTWH through different technologies plays a pivotal role in several process industries and domicile application. Heat pumps are widely employed to retrieve low level heat energy and also aid in reducing greenhouse gas emission. Hybrid absorption-compression heat pump showed maximum of 95% waste heat recovery rate, where air-source and CO2 trans critical heat pump reduced energy consumption by 60–75% and centrifugal heat pumps generated 9700 kW capacity of heat. Most of the studies reported the effective performance of absorption heat pump units with heat source temperature lie in the range of 60–120 °C along with maximum energy and exergy production with minor irreversible energy loss. Nanofluids are emerging as a high-performance working fluid for heating and cooling applications. Silver/pentane nanofluids increased overall system efficiency and showed 14% less carbon footprint, which is considered as a most effective alternate to hazardous working fluids. The simultaneous production of potable water and electrical power generation through desalination system was reviewed. The techno-economic assessment of using heat pumps in low grade energy recovery and its integrated prototype were presented in this paper together with the environmental impact of working fluids used in the heat pumps and thermodynamic cycles.
... Other studies have looked at introducing decentralised technologies such as heat pumps on an existing district heating system to highlight the capability of decentralised approaches in reducing carbon emissions. Arnaudo et al. (2021) have assessed waste heat recovery potential and electricity grid loading status in a real catchment in Sweden and suggested that decentralised heat pumps are suitable, but the associated carbon footprint heavily depends on the carbon emission factor from the supporting electricity sources. Arnaudo et al. (2020) looked at the impact of distributed heat pumps on an electricity distribution grid and has shown that with current demand patterns the local electricity grid could fail, but this could be mitigated to some extend through use and better management of distributed thermal energy storage units and thermal mass control in buildings. ...
A UK case study area containing over 33,000 households has been used to investigate spatial and temporal conflicts in meeting domestic heat demand through renewable electrical energy supply and low-grade decentralised heat recovery from the urban drainage network. The case study area was selected as its water infrastructure and population density were representative of the conditions experienced by the majority of the UK's urban population. The findings suggest that adopting an optimised and integrated water-energy system would lead to a 60% reduction in current carbon emissions, compared to a natural gas based system. The integrated water-energy system proposed for domestic heating showed an annual surplus of renewable energy of 716 GWh. However, a non-renewable source of energy of 114 GWh is required to deal with the intermittency of the demand and renewable energy supply. Given the renewable surplus, it would be possible to eliminate carbon emissions from domestic heating with the addition of local low efficiency inter-seasonal energy storage. Taking a broader perspective, the calculated 60% carbon emission saving is significant as the domestic housing sector contributes 15% of the UK carbon emissions. A progressive adoption of such locally based schemes throughout the country would be able to make tangible reductions to national carbon emission targets.
... The static payback period was estimated at 6 years compared with the baseline system. Arnaudo et al. [20] established the models to present the techno-economic and environmental benefits of waste heat recovery. The CO 2 emission and internal rate of return value were both reduced with the lower contribution of the adopted technology. ...
... According to the basic heat transfer formula, the heat transfer capacity can be calculated with Eq. (20). ...
Previously, the conventional fin-and-tube heat exchanger is usually chosen as the evaporator in the air source heat pump. Recently, with the higher heat transfer efficiency, the microchannel heat exchanger is increasingly recognized. Nevertheless, information available in the contrastive analysis of the two heat exchanger types is scarce. Therefore, the effect of the mentioned evaporator type on the air source transcritical CO2 heat pump was experimentally studied in this paper. Then, with the detailed techno-economic analysis methods, the heat pump with different heat exchangers is evaluated from multiple perspectives. Results showed the heating capacity and coefficient of performance of the microchannel system were increased by 16.5%-37.3% and 16.3%–22.6%, compared with the baseline fin-and-tube system. However, the attenuation degree of heating capacity was more obvious in the fin-and-tube system under the frosting condition. The primary energy consumption, CO2 emission and corresponding cost of microchannel system are declined by 6.28 tce, 14.4 tons and 77.6 dollars for the comparison with the fin-and-tube system. The maximum values are all presented by direct electric heater whereas the minimum life cycle cost is achieved by coal-fired boiler. The life cycle cost and sensitivity analysis with unit electricity price are also conducted in the economic analysis.
... According to statistics, the existing domestic hot water production methods mainly include coal-fired, gas-fired, and oil-fired boilers, solar heating systems, electric heating systems, and air source heat pump systems [1][2][3][4], etc. The water heating mechanism of boiler systems is to burn fossil fuels and convert the combustion heat into the heat energy of hot water; while the mechanism of electric systems is to consume electricity and convert electricity, solar energy, and other heat sources into the heat energy of hot water [5][6][7][8]. Compared with other hot water production methods, heat pump systems have the advantages of high efficiency, energy saving, eco-friendly, so they have a very good promotion and application prospect. ...
Compared with the traditional hot water production methods, heat pump systems have the unique advantages of high efficiency, energy saving, and eco-friendly, so they have a very good promotion and application prospect. The sewage source heat pump systems can recover the waste heat of high-temperature sewage produced in residential communities, for this reason, this study integrated the proven air source heat pump technology with the sewage source heat pump technology and conducted a research on the smart community waste heat recovery system based on the air-source/sewage-source Compound Heat Pump system (CHP system). In the paper, the design steps and equipment selection flow of the proposed system were given, the waste heat utilization rate of the proposed system was calculated, and the obtained experimental results verified the energy-saving effect of the proposed system, which had provided a reference for the application of the compound heat pumps in other occasions.
... In order to compare these two sides, net present value (NPV) calculations were performed, by taking an energy utility and an energy consumer's perspectives. The general NPV formula is the following one (Paper IV - [23]): ...
... For higher level of detail modelling, data concerning pipes' lengths, diameters and heat loss factors were provided by Stockholm Exergi. From this source also hourly based heat losses were obtained for validation purposes (Paper IV - [23]). ...
... As shown in Figure 26 (a), the waste heat recovery source is integrated in a LTDH subnet, connected to the 3 rd DH generation network of the city (HTDH). LTDH has the potential of reducing the network heat losses and of accommodating a larger share of waste heat recovery resources (Paper IV - [23]). The LTDH subnet of this case has a fixed supply temperature of 65 °C, so that no additional temperature boosting is required for DHW purposes. ...
As major responsible for CO2 emissions, the energy sector is urgently called to take action against climate change. The integration of renewable energy resources is a solution that, however, comes with a challenge. In fact, renewables are often variable, unpredictable and distributed. These characteristics add an extreme complexity to the design and control of energy systems. Sector-coupling is nowadays strongly supported as a promising approach to increase the flexibility of these systems. For example, wind power curtailment can be reduced by using the power surplus to operate heat pumps. When the wind does not blow, the heat stored in the thermal mass of the buildings and waste heat recovery can be used instead. These solutions are largely available at district-to-city level. However, a suitable framework to design these integrated urban energy systems is missing.
This thesis work proposes such a framework, as a set of methodological steps and integrated modelling tools. Among them, the modelling and simulation approach is a fundamental aspect. Given the heterogeneity of integrated energy systems, dedicated technology-specific models are developed and used to achieve the required level of detail. A co-simulation method is implemented when time step coordination and data exchange are necessary. Scenarios are developed to compare the techno-economic and environmental performance of alternative solutions, based on sector-coupling. Levelized cost of energy and CO2 emissions are used as main performance indicators for this purpose. In order to show the applicability of this methodology, Hammarby Sjöstad (Stockholm, Sweden) is selected as a case study. This also allows to tackle a real local open issue, which is the definition of the best solution between district heating and domestic heat pumps for multi-apartment buildings.
The proposed framework was successfully applied to the case study. Case specific results allowed to formulate more general conclusions applicable to similar multi-apartment residential districts, in a Swedish context. It could be shown that co-simulation is a useful approach to capture sector-coupling bottlenecks and opportunities. Respective examples are electricity grid overloadings caused by installations of heat pumps and the control of thermal mass in buildings to replace the use of heat peak boilers. However, co-simulation should be strictly limited to cases where control feedback loops need to be taken into account, such as in the previous examples. This is because it involves a higher implementation complexity and a higher computational time. Thus, for example, the models of a heat network and of an electricity grid with no coupling technologies, such as heat pumps and electric boilers, should be preferably analyzed sequentially. The levelized cost of heat was found to be a game-changer parameter when comparing energy infrastructures, beyond the specific business aspects. For example, the replacement of a district heating tariff with its levelized cost of heat clearly showed the economic advantage of heat networks against domestic heat pumps. The CO2 emissions factors of different energy resources (waste, biomass, electricity mix) were shown to be highly critical for two main reasons. Firstly, different assumptions for these factors led to opposite findings regarding the carbon footprint of specific technologies. For example, heat pumps could be estimated as both more and less polluting than district heating, depending on the assumed emission factors. Secondly, control strategies based on the CO2 emission factors of the electricity supply mix (power-to-heat) were found to be a promising sector-coupling solution. By analyzing integrated energy systems, it was possible to assess uncovered bottlenecks and suggest new options. In particular, it was shown that the installation of a large number of distributed heat pumps can overload the electricity distribution grid in a district. Demand side management, through the thermal mass in buildings and vehicle-to-grid, could help alleviating this problem. On the other hand, district heating was found to be an even more promising alternative, by integrating demand side management and heat recovery. Heat pumps were shown to be a suitable partner technology for supporting heat recovery and enabling power-to-heat.
