District Heating Schemes Research Articles

Who has the power? Reflections on citizen engagement in district heating schemes in the UK and Sweden

District heating (DH) schemes linked to Energy from Waste (EfW) and Biomass facilities have been championed for their potential to decarbonise heating yet their role in energy policy is contested. These schemes are a unique intersection between two vital environmental policy agendas - waste and energy - and can offer opportunities for citizens to affect both environmental agendas and future energy infrastructures.Much has been written on the technical opportunities of DH and its policy landscape. This paper explores an important missing piece, to explore to what extent and how DH schemes support citizen engagement in local heat infrastructure decision-making. The benefits of citizen engagement are understood but there is currently no clear and consistent implementation of stakeholder engagement policy in this area. Evidence from four qualitative case studies is presented from the UK and Sweden to investigate strategies used by developers and operators to engage with stakeholders and how this influences their decision-making. However, limited examples of bottom-up, unplanned moments of citizen engagement were found as practice fails to live up to theory and policy rhetoric: ownership structures came through in our research as a key factor in this disconnect.

Hot air or new energy: Are we seeing signs of improved citizen engagement in district heating schemes?

<h2>Abstract</h2> District heating (DH) schemes linked to Energy from Waste (EfW) and Biomass facilities have been championed for their potential to decarbonise heating yet their role in energy policy is contested. These schemes are a unique intersection between two vital environmental policy agendas - waste and energy - and can offer opportunities for citizens to affect both environmental agendas and future energy infrastructures. Much has been written on the technical opportunities of DH and its policy landscape. This paper explores an important missing piece, to explore to what extent and how DH schemes support citizen engagement in local heat infrastructure decision-making. The benefits of citizen engagement are understood but there is currently no clear and consistent implementation of stakeholder engagement policy in this area. Evidence from four qualitative case studies is presented from the UK and Sweden to investigate strategies used by developers and operators to engage with stakeholders and how this influences their decision-making. However, limited examples of bottom-up, unplanned moments of citizen engagement were found as practice fails to live up to theory and policy rhetoric: ownership structures came through in our research as a key factor in this disconnect.

Comparing district heating options under uncertainty using stochastic ordering

District heating is expected to play an important role in the decarbonisation of the energy sector in the coming years since low carbon sources such as waste heat and biomass are increasingly being used to generate heat. The design of district heating often has competing objectives: the need for inexpensive energy and meeting low carbon targets. In addition, the planning of district heating schemes is subject to multiple sources of uncertainty, such as variability in heat demand and energy prices. This paper proposes a decision support tool to analyse and compare system designs for district heating under uncertainty using stochastic ordering (dominance) so that decision-makers can make robust decisions. The uncertainty in input parameters of the energy system model together with general scenarios are introduced to generate distributions of net present costs and emissions for each design. To perform inference about the induced distributions of outputs, we apply the orderings in the mean and dispersion. The proposed approach is demonstrated in an application to the waste heat recovery problem in district heating in Brunswick, Germany. The results obtained show that heat pump, a low carbon design option, is more robust in comparison to combined heat and power (CHP) and a mix of CHP and heat pump under all three scenarios, highlighting that robustness is an attractive feature of low-temperature waste heat recovery. • Decisions regarding energy planning involve uncertainty. • New low-carbon technologies are being introduced as part of district heating. • Stochastic ordering is proposed to compare the system designs’ performance under uncertainty. • The orderings in mean and dispersion are considered for waste heat recovery.

Thermal and Economic Analysis of Heat Exchangers as Part of a Geothermal District Heating Scheme in the Cheshire Basin, UK

Heat exchangers are vital to any geothermal system looking to use direct heat supplied via a district heat network. Attention on geothermal schemes in the UK has been growing, with minimal attention on the performance of heat exchangers. In this study, different types of heat exchangers are analysed for the Cheshire Basin as a case study, specifically the Crewe area, to establish their effectiveness and optimal heat transfer area. The results indicate that counter-current flow heat exchangers have a higher effectiveness than co-current heat exchangers. Optimisation of the heat exchange area can produce total savings of £43.06 million and £71.5 million, over a 25-year lifetime, in comparison with a fossil-fuelled district heat network using geothermal fluid input temperatures of 67 °C and 86 °C, respectively.

Waste heat mapping: A UK study

The following study considers the spatial distribution, grade and seasonal variation of waste-heat from industrial sectors in the United Kingdom in 2018. Opportunities to offset the emissions caused by heat generation through the use of waste-heat recovery schemes have been examined. Reducing heat waste is a key intermediate step in avoiding climate disaster until fully decarbonised industrial practices have been developed and implemented. The findings of this study are presented as a ‘UK waste heat map’. Data containing information on the natural gas consumption of different industries are used as a proxy for waste heat. This report finds that waste heat is concentrated around densely populated areas and areas with a traditionally strong industrial base. Such areas generate a large amount of the waste heat suitable for heat reuse, such as in a district heating scheme. The total waste heat from UK industry and electricity generation is estimated to be nearly 391,000 GWh per year. The data are represented in the accompanying UK waste heat map as point location data and by waste heat per Local Authority. Opportunities have been identified within each major industrial sector to reclaim and utilise this waste heat.

Who Has the Power? On Engagement and Ownership in District Heating Schemes in the UK and Sweden

Who Has the Power? On Engagement and Ownership in District Heating Schemes in the UK and Sweden

Successful implementation of low temperature district heating case studies

Low temperature district heating is recognized as a key technology for the (cost-) efficient integration of renewable energy and waste heat sources in our energy systems. Several studies indicate that a deployment of local district heating schemes is a key measure for reaching the politically set climate goals. Further, implementation of low temperature district heating systems are recommended for taking maximum advantages of synergies with other sectors for decarbonization of the heating sector. Within the IEA DHC Annex TS2 project already realized low temperature community energy system concepts as well as planned or designed systems are identified and visualized. Furthermore, projects showing an innovative heat use or operation of buildings are also included in the analyses. The different projects are assessed and compared. The presentation of the demonstrators is set up in such a way that knowledge is generated about the indoor heating system, the district heating system and of the competitiveness of low temperature district heating systems, giving the evidence that these systems are feasible, efficient and reliable under various boundary conditions. The demonstrators further indicate that there are existing challenges, where further research on innovative district heating concepts for integrating decentral feed-in of renewable energy is required. The demonstrators included in the IEA DHC Annex TS2 are analysed in regard to which elements of new knowledge they can generate. For each demonstrator there are specific innovations in focus. Furthermore, the case studies show that the related business models for the utilities change when system temperatures are lowered. The paper presents and discusses the results from current research work within of the IEA DHC Annex TS2 on Implementation of Low Temperature District Heating Systems (Averfalk et al., 2021; Annex TS2, 2021 [1]).

TECHNICAL AND ECONOMIC EFFICIENCY OF COMBINED DISTRICT HEATING WITH LOCAL HEAT SOURCE FOR DISTRICT HOT WATER

The scheme of combined district heating systems is used, in which centralized heating is used for heating and local heat source is used for hot water supply. A mathematical model has been developed that allows to perform a comparative analysis of the technical and economic characteristics of two scenarios of modernization of the heat supply system: replacement of boilers, heat networks and pumps while using the traditional hot water supply scheme, and replacement of these elements in combination with the installation of a local hot water supply source that provides the hot water supply. hot water by means of a local heat network whose length is substantially smaller than the existing one. Electric heaters and solar collectors with electric heating are proposed as local heat sources. The advantages of combined district heating schemes on the planning horizon of 10 years are shown. The analysis of the influence of various factors on the advantage of the combined scheme of district heating is performed. The developed model can be used for preparation of feasibility studies of projects of energy efficient modernization of district heating systems. Ref. 4, Fig. 7, Tab. 1.

Heating and controls use resulting from shared-cost charges in communal network social housing

In dwellings connected to district or communal heating schemes occupants are commonly charged based on actual heat consumption, providing a direct link between heat consumption and weekly heating cost. This article investigates how the use of fixed-rate, shared-cost charging without dwelling-level metering affects the heating and controls use in communal network social housing. Living room and radiator temperatures in 50 flats were monitored over a winter heating season and occupants surveyed at monitoring install and removal. The primary stated and observed heating strategy was to leave the heating always on and control through the radiator thermostatic radiator valves. Of people who used timer control, total heating hours reduced with increased frequency of manual intervention. Mean indoor temperatures up to 27.7°C were observed, implying many residents are adapted to higher indoor temperatures. Thus, the current model encourages wasteful behaviour and education on use of controls is key to transitioning residents to charging for actual heat use. Practical application: This article intends to inform the landlords of communal network social housing schemes on the impacts that shared-cost recovery methods of charging for heat has on heating and controls use. This charging method can impact the behaviour of the network occupants resulting in higher heat consumption, overall higher heating costs and subsequently higher carbon emissions from the site if occupants are not adequately trained in how to operate their heating effectively. Where similar charging methods are implemented, the article hopes to inform operators of the potential vulnerabilities of the network occupants to changes in the method of charging for heat.

The potential use of mine water for a district heating scheme at Caerau, Upper Llynfi valley, South Wales, UK

The feasibility of recovering heat energy from mine water contained within an abandoned coal mine in South Wales is assessed for a proposed district heating scheme. The study area is the village of Caerau, in the Upper Llynfi valley, Bridgend County Borough, South Wales, UK, comprising around 750 residential houses, a primary school and 17 commercial properties. This paper describes an archival geological and mining desk study focused on Caerau colliery, consideration of regional mine linkages, geographical information system (GIS) techniques used to create a 3D initial conceptual geological mine model of Caerau workings, permitting and licencing requirements, community engagement activities undertaken and the findings of a single exploratory borehole. The borehole intersected a void space in flooded mine workings around the horizon of the Six Foot seam at a depth of 224 m below ground level, as predicted by the conceptual mine model. The rest water level within the borehole lies at 92 m below ground level and the measured in situ temperature of the mine water at the base of the borehole was 20.3°C. An unexpectedly high and sustained geothermal gradient of c. 53°C km −1 was calculated from repeated measured temperature profiles. Thematic collection: This article is part of the Keeping lessons alive in engineering geology collection available at https://www.lyellcollection.org/cc/keeping-lessons-alive-in-engineering-geology

Efficient and cost-effective district heating system with decentralized heat storage units, and triple-pipes

The novel concept of district heating system with decentralized heat storage units, different supply temperatures and two pairs of parallel twin-pipes was recently proposed and investigated thermodynamically. In this work, the use of triple-pipes for the distribution and service segments of the pipeline of this district heating scheme (where the transmission segment remains with twin-pipe type) is proposed and investigated. For this, computational fluid dynamic methods together with Evolutionary Polynomial Regression/Multi-Objective Genetic Algorithm approach are used to drive reliable correlations for estimating the rate of heat losses from the twin- and triple-pipes. The validity of the numerical simulations and the developed correlations are examined with the available data in the literature. Then, the performance of the specific district heating system in its conventional form and the revised design (i.e. when employing twin- and triple-pipes) is investigated and compared. The results show that the use of triple-pipes for the district heating improves the overall energy efficiency of the system by offering a considerably lower rate of heat loss through the distribution and service pipes. In addition, this eliminates the need for the secondary pairs of distribution and service twin-pipes, decreasing the costs of the system.

An Investigation into the Limitations of Low Temperature District Heating on Traditional Tenement Buildings in Scotland

Domestic heating accounts for 64% of domestic energy usage in the UK, yet there are currently very few viable options for low carbon residential heating. The government’s carbon plan commits to improving the uptake of district heating connections in new build dwellings, but the greatest carbon saving can be made through targeting traditional housing stock. This paper aims to quantify the potential carbon and energy savings that can be made by connecting a traditional tenement building to a district heating scheme. The study uses a transient system simulation tool (TRNSYS) model to simulate the radiator system in a tenement block and shows that a significant benefit can be achieved by reducing the supply temperature; however, the minimum supply temperature is drastically limited by the building condition. Therefore, the study also critically compares the benefits of a lower supply temperature against minor refurbishments. It was found that improving building conditions alone could offer a 30% reduction in space heating energy consumption, while building improvements and integration of a river source heat pump could offer almost a 70% reduction. It is the recommendation of this study that a dwelling be improved as much as economically possible to achieve the greatest carbon and energetic savings.

CFD analysis of triple-pipes for a district heating system with two simultaneous supply temperatures

Employing triple-pipes for simultaneous yet separate supply of space heating and domestic hot water demands of district heating network is an interesting solution for decreasing the rate of losses and increasing the cost-effectiveness of district heating systems. Although the thermodynamic performance of triple-pipes has been studied before, there is not any detailed performance analysis of such pipes, especially for the specific two-supply-temperature district heating design. This study employs computational fluid dynamic methods to investigate the feasibility of using triple-pipes for this district heating scheme and presents a detailed report of the thermal behavior of such pipes under different operational conditions including different pipe arrangements within the casing. For better understanding the effect of using triple-pipes in such a district heating system, the results obtained for this type of pipe is compared to those given for a twin-pipe in a regular district heating system. The results show that a triple-pipe with any arrangement is better than a twin-pipe supply method while this enhancement can be much better with a triangular arrangement of the three lines within the casing. With certain supply and return temperatures for a 10 km long pipeline, the rate of heat loss from the most efficient triple-pipe design is only 80 kW while it is about 145 kW for the twin-pipe system.

Getting hotter: are heat networks about to take off in the UK?

The UK's heat sector accounts for about a fifth of national CO2 emissions, and the government's advisory Committee on Climate Change has been highly critical of efforts to decarbonise it. In a recent report it recommends that new homes should not be connected to the gas grid from 2025. Instead, it says, they should be built on systems such as heat networks, where a group of buildings are linked to a central energy source through underground pipes. The promise of heat networks, also known as district heating systems, is that they can provide greener heating to many homes or businesses at once and may be cheaper and more reliable than alternatives. The UK's first district heating scheme was built in Pimlico in the 1950s to funnel waste heat from Battersea Power Station to thousands of homes and businesses. Heat networks grew in popularity and some councils bought into them enthusiastically, particularly for social housing. But the idea never gathered steam the way it did in parts of Europe, particularly the Nordic countries, Germany and the Netherlands, and fizzled out in the latter part of the 20th century.

Thermal-Hydraulic Performance Analysis of Twin-Pipes for Various Future District Heating Schemes

Future energy systems will come with a 100% share of renewable energy and high integration of energy systems. District heating and cooling systems will be undeniable parts of the future energy systems, as they pave the bed for high-efficiency, low cost, and clean production. District heating systems may come into a wide range of designs in the future. Currently, most of the world’s district heating systems are based on the third generation design while everything in this framework is on the verge of a transition to the fourth generation. A large number of technologies for the future district heating systems has been proposed so far, among which low-, ultralow- and variable-temperature systems seem more of qualification. This study employs computational fluid dynamics to make a comprehensive examination of the compatibility of regular twin-pipes with various potential district heating schemes for future energy systems. The results show that both low- and ultralow-temperature systems could efficiently use regular twin-pipes commonly used in the third generation district heating systems, though the insulation of the pipe could be proportionally strengthened based on a techno-economic trade-off. In contrast, the results show that the thermal inertia of the pipe does not allow the variable-temperature district heating system to effectively operate when the transmission pipeline is longer than a limited length. Therefore, a regular heat distribution network may not be an appropriate host for a variable-temperature district heating scheme unless decentralized heat production units come into service.

District Heating Challenges for the UK

District heating uptake has grown with the increasing need for cleaner and more efficient energy supply. This has resulted in a rising number of new developments signing up to a district heating scheme, typically powered by Combined Heat and Power (CHP) boilers or biomass boilers with supplemental electrical or gas grid connections. These schemes have advanced rapidly in recent years, with much of the research focus targeting lower carbon technologies, improved load prediction and peak demand management. We assess the current status of District Heating Networks (DHNs) in the United Kingdom using published case studies and suggest next steps to improvement. Our findings show that the United Kingdom has good potential for uptake of district energy given the current political climate and government incentives, however significant improvements must be made to further penetrate the heating market.

Non-uniform temperature district heating system with decentralized heat pumps and standalone storage tanks

In this work, the novel concept of non-uniform temperature district heating (NUTDH) system with decentralized heat pumps and standalone heat storage units (HPHS) is proposed. In the NUTDH-HPHS system, the temperature within the transmission pipeline is always at the ultra-low level of 35–40 °C, which is sufficient for space heating use. The heat pumps will increase the temperature within the distribution pipes to 70 °C during a short period of time a day. This temperature is to provide the domestic hot water (DHW) need of the consumers. Heat pumps are sized in neighborhood scale, and as each neighborhood is supplied with a high temperature just for a short time a day, each heat pump may be assigned for a few neighborhoods. As not always high-temperature water is available, the substations are equipped with storage tanks. In this system, the rate of heat loss is minimal, legionella risk is absolutely zero, and there is a strong synergy between the power and heat sectors. The system is designed and analyzed for a case study. The results are also compared with the performance of other popular district heating (DH) schemes. It is demonstrated that the NUTDH-HPHS system shows the best performance.

Comparative analysis of the efficiency of the application of thermal-hydraulic distributor with classical schemes of connecting subscribers

Analysis of the use of a thermo-hydraulic distributor in district heating schemes showed insufficient study of the mutual influence of the connected circuits, on which the coefficient of hydraulic stability of the heating network depends, and the lack of a comparative analysis of the efficiency of heat supply when using a scheme with a thermo-hydraulic distributor compared to widely used subscriber connection schemes. The purpose of the study is to compare the economic and energy efficiency of the proposed and existing subscriber connection schemes, which is an important task. In laboratory conditions, a wide range of studies have been carried out to study the hydraulic dependence of the contours of the thermo-hydraulic distributor among themselves. Processing of the results was carried out by the method of correlation-regression analysis and mathematical statistics. In a comparative analysis of subscriber connection schemes, methods of physical modeling of thermo-hydraulic modes were used. A comparative analysis showed that the energy efficiency of the scheme with a thermo-hydraulic distributor is higher in heating systems with non-automated subscribers, regardless of the temperature graph of the heating network. When comparing schemes with parallel connection of a hot water heater, it was found that the totality of electricity consumption for coolant circulation and fuel costs for a circuit with a thermo-hydraulic distributor turned out to be less irrespective of the temperature schedule. Statistical research methods confirmed the independence of the circuits and the normal supply of heat to the heating. New solutions have been obtained to increase the hydraulic stability of the centralized heat supply system using a thermo-hydraulic distributor at a heating point – the hydraulic stability coefficient of the heat network during all subscriber operation modes is equal to one. The results of the study can be used in the design of thermal points: the proposed heating system, the consumers of which will provide a stable hydraulic mode; existing heat supply system, the consumers of which must ensure the hydro-stable control of heat.

Non-uniform temperature district heating system with decentralized heat storage units, a reliable solution for heat supply

In this work, the novel concept of non-uniform temperature district heating system is proposed and analyzed. This system mainly works on a low-temperature supply mode for space heating, while it goes to high-temperature mode for domestic hot water supply only 4 h a day. The system employs decentralized heat storage units to be charged during the high-temperature mode. In this way, the system operates based on a minimum rate of heat loss and there is no legionella risk due to thermal disinfection. The system is designed for a town in Brazil and a detailed thermodynamic model of the system is presented. The performance of this system is compared with other popular district heating schemes. With a total annual heat loss of 64 MWh, the proposed system outperforms the third generation technology in which the loss is almost double. As such, although the heat loss of the ultralow-temperature system is 28% lower (i.e. around 50 MWh), the non-uniform temperature system is still preferred to this case as well. This is because not only the proposed case supplies both of the hot water and space heating demands of the buildings, but also it does not need any further actions for legionella prevention.

Technology adoption, consumer inattention and heuristic decision-making: Evidence from a UK district heating scheme

This paper contributes to the debate on the energy efficiency paradox according to which consumers fail to adopt cost-effective, energy efficient technologies over less efficient technologies and therefore fail to reduce energy consumption. Both traditional and behavioural theories are used to investigate the decision-making process of residential consumers with empirical evidence based upon a specially designed quasi-experimental survey of 784 households on the decision to connect to a district-heating system, a more energy efficient alternative to individual heating systems. The results suggest an internal discount rate of around 36 per cent for homeowners, a signal that consumers undervalue future energy costs. We also find the household’s decision to be negatively affected by years of payback up to around 7–8 years. Our findings suggest that neglecting consumer inattention and heuristics can lead to biases which cast doubt on the existence of the energy efficiency paradox. We believe that these results help to explain why some consumers are unlikely to invest in energy efficient technology, particularly those on low incomes.