This master thesis has examined how two of the heat pumps at Norrenergi, Solnaverket, can be converted to steam driven heat pumps. The heat pumps are driven by electrical motors today and this thesis has investigated the technical and economical aspects of replacing them with steam turbines and also installing a pellet boiler. The purpose with this project is to lower the costs for the heat pumps which varies with the electricity price, where the electricity taxes represent about 40-60 % of the total electricity cost. In addition, Norrenergi is one of the largest electricity consumers in Stockholm. This, combined with the prevailing capacity shortage in Stockholm makes it important to examine another alternative than electricity for the heat pumps. Capacity shortage means that electricity can't be transmitted into the city during periods with high electricity demand. The results of this master thesis show that the costs reduces on a system level when two steam driven heat pumps are installed compared to the electrity driven heat pumps. All district heating plants in Stockholm, including Söderenergi's, Norrenergi's and Stockholm Exergi's plants, have been involved while examining the costs in this study. Despite the cost reduction the investment calculation shows that the investment is not profitable for a low or average electrity price. For a high electricity price the investment seems to be profitable, but this is not considered enough for the investment to be recommend since future electricty prices are hard to predict. On the other hand there might be other aspects than economical to invest in this type of district heating plant, for example from a sustainability perspective. / Norrenergi är ett fjärrvärme- och fjärrkylabolag i Stockholm som bland annat producerar värme via energiåtervinning i en VP-anläggning i Solnaverket. Värmepumparna har en total värmeeffekt på 100 MW och drivs av elektricitet samt spillvatten från Bromma reningsverk. Kostnaden för att producera fjärrvärme via värmepumpar varierar med elpriset där en betydande faktor är elskatten. Elskatten utgör ungefär 40–60 % av den totala elkostnaden för VP-anläggningen i Solnaverket. Utöver de höga kostnaderna för att driva VP-anläggningen råder en så kallad kapacitetsbrist i Stockholm vilket bland annat grundar sig i att staden växt i en snabbare takt än utbyggnaden av stamnätet. På grund av ovan nämnda orsaker är det intressant att undersöka alternativa lösningar för hur den eldrivna VP-anläggningen kan producera fjärrvärme, dels för att minska kostnader för elektricitet men också för att bidra till en samhällsnytta genom att minska effektuttaget på elnätet. Detta examensarbete ämnar därför undersöka hur två av värmepumparna i Solnaverket kan omvandlas från eldrift till mekanisk ångdrift via ångturbiner, där ångturbinerna i sin tur drivs av ånga från en pelletspanna. Därtill undersöks systemdriftsnyttan, där även Stockholm Exergis och Söderenergis anläggningar beaktas, samt lönsamheten för att konvertera två av värmepumparna till ångdrift. Resultatet visar att systemdriftsnyttan är positiv oavsett elprisprofil vilket beror på att kostnaderna på systemnivå minskar när ångdriven VP-anläggning implementeras i Solnaverket. Trots den positiva systemdriftsnyttan visar dock investeringskalkylen att denna investering endast är lönsam vid ett högt elpris. Det beror bland annat på att den positiva systemdriftsnyttan inte är tillräckligt hög (vid låg och medelelpris) för att uppnå ett tillräckligt högt nuvärde med given kalkylränta och ekonomisk livslängd, i jämförelse med grundinvesteringskostnaderna. Den låga lönsamheten beror dessutom på att Stockholm Exergi ska bygga ett nytt avfallskraftvärmeverk i Lövsta som har billigare produktionskostnader än den ångdrivna VP-anläggningen. Det är svårt att förutspå elprisets utveckling framöver och variationerna i elpris under året förväntas öka, därför är det rekommenderat att denna investeringen inte genomförs eftersom den beror så pass mycket av elpriset. Det kan dock finnas andra aspekter än ekonomiska i att investera i en ångdriven VP-anläggning. Till exempel ur ett hållbarhetsperspektiv då belastningen på elnätet minskar när de eldrivna VP:arna konverteras till ångdrift.

The district heating system (DHS) of Stockholm is one of the largest systems in the world with a total yearly production of 10TWh of heat and 2TWh of electricity (through combined heat and power plants). Large amounts of greenhouse gasses (GHG) are emitted to produce this heat and electricity. Given the goal of the City of Stockholm to reduce the amount of GHG emissions to 3 ton per capita in 2015 and to keep reducing emissions at a similar rate after 2015, it is important to identify the potentials for further reductions. Numerous studies have been done on how the DHS can become more sustainable by installing new generation units. However, also the consumers have an influence on the DHS. After all, it are the consumers who decide when and how much heat or electricity they use. Most former studies and environmental guidelines for the DHS in Stockholm focussed on the producer side. This thesis looks at the consumer perspective of the (heat of the) district heating system. A real-time signal giving the greenhouse gas emissions of individual households is developed and its potential and challenges are discussed. With this signal, households that want to minimise their environmental impact have a tool to decrease their environmental impact by changing their consumption. This can be a first step to transform the DHS to a smart district heating system. First, generic models to calculate the dynamic greenhouse gas intensity of the heat production of district heating and to calculate the greenhouse gas emissions related to the heat consumption of households are suggested. Then the feedback signal with those real-time household emissions is calculated for representative households in Stockholm based on data of Stockholm’s DHS and data about hot tap water consumption in Sweden. Results indicate that variations in household level greenhouse gas emissions mostly reflect changes in consumption but can also result from changes by the producer. Intraday variations are mostly caused by changes in hot tap water consumption, while variations on a timescale of a few days are caused by changes in heating consumption (changing weather) and changes made by the producer (to use different fuels). Then several scenarios are calculated, each scenario looking at the actions a consumer can take to shift or reduce his/her consumption (decrease hot tap water usage, lower indoor temperature etc.). The real-time household emissions are calculated again to see if the signal gives the needed incentives (is the household rewarded for its effort? Does it get further incentives?). It was found that a strong time-incentive (to decrease consumption when it saves most emissions) is missing if the average perspective is used to calculate the emission intensity of the heat production. Also, the results confirmed the finding that the feedback signal might not reflect changes in consumption. Finally, challenges for the signal are discussed. One of the major hurdles is the fact that household consumption of heat (heating and hot tap water) can often not be measured on a household level. Thus, it has to be estimated but it seems very difficult to get this estimation accurate enough to give correct feedback to households, especially about the emissions saved by their efforts to reduce/shift their consumption. Secondly, the time resolution should be chosen well to still get accurate results but not make the signal to data-intensive. Finally, the result is heavily dependent on the chosen methodology (average or marginal perspective? Do you account for the electrical side of the DHS? How about the distribution losses? Etc.).

The industrial sector accounts for a large share of greenhouse gas emissions. To reduce its negative impact on the environment is crucial in the quest for a sustainable future. In discussions of the industrial sector's impact on the environment guidelines have been highlighted as a tool to assist the industries in their efforts to change the relationship between the consumption of energy and production. This by improving energy efficiency and a shift to the best available technology. During the past 30 years the steel industry has reduced its energy consumption per ton of steel produced by 50 percent. However, due to this dramatic improvement in energy efficiency, it is estimated there is now only room for a marginal further improvement on the basis of existing technology. More innovative solutions are therefore required to further improve energy efficiency and achieve a more sustainable use of resources. In a description of the program Efficiency of Energy Use in Industry – Research and Development undertaken by the Swedish Energy Agency the interaction between industry and society is accentuated as an important factor in energy efficiency efforts. Today, there are already several examples of where the industry and the community work together to achieve a better utilization of resources. The steel industry SSAB EMEA has a manufacturing plant in Borlänge, Sweden, where they have been recycling waste heat from the industrial processes for a long period of time. In 1991 SSAB initiated collaboration with the local energy company regarding recovery of waste heat within the industrial enterprise. Since then, SSAB has contributed to the heating of the residences that are connected to the local district heating network. The present study aims to examine the values that the utilization of waste heat add to the industrial company and the community, and to explore how the use of industrial waste heat can be developed ahead. The examination consists of a case study and is mainly based on qualitative interviews with people from SSAB, the local energy company Borlänge Energi, Borlänge Municipality and the Swedish Energy Agency. Some quantitative data, such as measurements of heat deliveries, have also been used for the analysis. In addition a literature review with a focus on district heating in Sweden, industrial waste heat and instruments in energy and climate policy has been conducted. Through varied system levels the waste heat collaboration in Borlänge has been analyzed from a business, social and sustainable perspective. The result of the case study proves that the waste heat collaboration has added value in all perspectives. Business values that have been identified are reduced purchases of oil, compensation for delivered waste heat, exchange from vapour to in-house district heating within the steel factory site, reduced emissions of carbon dioxide, media attention and an improved brand and that the waste heat collaboration possibly made SSAB a more desirable employer. The use of industrial waste heat for district heating in Borlänge has also generated a range of social benefits, which consist of low operating costs for heat, low price of district heating, good energy mix and better air quality and less acidity. From a sustainability perspective, the waste heat utilization resulted in reduced emissions of carbon dioxide and other air pollutants and has been contributive to a sustainable use of raw materials and energy resources. The results also demonstrate that there are both opportunities and threats to a continued use of industrial waste heat. The opportunities identified are regional district heating networks, which can improve the conditions for effective use of waste heat, district cooling, which may increase the need for waste heat in the summer and in-house electricity production, which can accommodate some of the steel company's electricity need. A few threats to a continued use of waste heat have also been identified, which the first consists of co-generation and waste incineration, which can adversely affect energy companies incentives to enter into and renew agreements on waste heat deliveries since the companies do not want to be afflicted with reduced revenues from sales of electricity and electricity certificates or from the reception of waste. Furthermore has changes in energy policy been identified as a threat since for example a new tax on waste heat could worsen the conditions for both continuing and new waste heat collaborations. / Industrisektorn står för en stor andel av växthusgasutsläppen. Att minska dess negativa inverkan på klimatet är således grundläggande i strävan efter ett hållbart samhälle. I diskussioner kring industrisektorns påverkan på miljön har riktlinjer lyfts fram som ett instrument för att bistå industrin i arbetet med att förändra förhållandet mellan konsumtion av energi och produktion. Detta genom en förbättring av energieffektiviteten och en förskjutning till bästa möjliga teknik. Under de senaste 30 åren har stålindustrin reducerat sin energikonsumtion per ton producerat stål med 50 procent. Det sägs dock att dessa dramatiska framsteg i energieffektivitet har lett till att det nu endast finns rum för en marginell fortsatt förbättring förutsatt befintlig teknik. Om så är fallet måste våra vyer vidgas för att vi ska kunna hitta lösningar som innebär större effektivitetsvinster och ett bättre nyttjande av resurser. I en beskrivning av programmet Effektivisering av industrins energianvändning – forskning och utveckling som drivs av Energimyndigheten betonas samspelet mellan industri och samhälle som en viktig faktor i energieffektiviseringsarbetet. Idag finns det redan flera exempel på där industrin och samhället samarbetar för att uppnå ett bättre nyttjande av resurser. I Borlänge har stålföretaget SSAB EMEA en produktionsanläggning där de sedan länge återvinner restenergier från verksamhetens processer. År 1991 ingick SSAB avtal med det lokala energibolaget avseende tillvaratagande av restvärme vid industriföretaget. Sedan dess har SSAB bidragit till uppvärmningen av de bostäder som är anslutna till ortens fjärrvärmenät. Föreliggande studie har som syfte att undersöka vilka värden som tillvaratagandet av restvärmen tillför industriföretaget och samhället, samt ta reda på hur användandet av industriell restvärme kan komma att utvecklas framåt. Undersökningen består av en fallstudie och bygger i huvudsak på kvalitativa intervjuer med personer från SSAB, det lokala energibolaget Borlänge Energi, Borlänge kommun och Energimyndigheten men också på kvantitativ data, såsom mätningar av värmeleveranser. Sedan har även en litteraturstudie genomförts med fokus på fjärrvärme i Sverige, industriell restvärme och styrmedel i energi- och klimatpolitiken. Genom varierade systemnivåer har restvärmesamarbetet i Borlänge analyserats ur företagsekonomiskt, samhällsekonomiskt och hållbart perspektiv. Resultatet av fallstudien visar att restvärmesamarbetet tillfört värden inom samtliga perspektiv. De företagsekonomiska vinster som har identifierats är minskade inköp av olja, ersättning för levererad restvärme, byte från ånga till intern fjärrvärme inom stålföretagets verksområde, minskade utsläpp av koldioxid, medial uppmärksamhet och stärkt varumärke och att restvärmesamarbetet eventuellt gjort SSAB till en mer attraktiv arbetsgivare. Användandet av industriell restvärme som fjärrvärme i Borlänges lokala fjärrvärmenät har även genererat en rad samhällsekonomiska vinster, vilka utgörs av låg driftskostnad för värmeproduktion, lågt pris på fjärrvärme, bra miljömix samt bättre luftkvalitet och mindre försurning. Ur ett hållbarhetsperspektiv har restvärmenyttjandet resulterat i minskade utsläpp av koldioxid och andra luftföroreningar och varit bidragande till ett hållbart nyttjande av råvaror och energiresurser. Resultatet visar också att det finns både möjligheter och hot för ett fortsatt användande av industriell restvärme. De möjligheter som identifierats är regionala fjärrvärmenät, som genom omfattande värmeunderlag kan förbättra förutsättningarna för effektiv användning av restvärmen, fjärrkyla, som kan öka behovet av restvärmen under sommarhalvåret och egen elproduktion, som kan tillgodose en del av industriföretagets elbehov. Sedan har även hot för ett fortsatt användande av restvärme identifierats, vilken den första utgörs av kraftvärme och avfallsförbränning, som kan inverka negativt på energibolags incitament till att ingå och förnya avtal om restvärmeleveranser då bolagen inte vill riskera att drabbas av minskade intäkter från försäljning av el och elcertifikat eller från mottagande av avfall. Även förändringar i energipolitiken har identifierats som ett hot då exempelvis en ny beskattning på restvärme kan försämra förutsättningarna för både fortsatta och nya restvärmesamarbeten.

This project aimed to investigate the existence of thermal surplus energy from the ice rinks at Gränby Sports Field, Uppsala. Furthermore, a secondary goal was to suggest a distribution system for sharing the potential surplus energy. To fulfil the purpose, each ice rink was modelled in the software IDA ICE. The following ice rinks were considered: buildings A and B, building C and the bandy arena. Data regarding the total heat and cold consumption for each building was collected from the owner, Uppsala kommun Sport- och rekreationsfastigheter AB, and was used to validate the simulation results from the building models. The results from IDA ICE were presented in graphs that illustrate each ice rink’s total heat and cold consumption, surplus energy and energy balance. However, the results from the models in IDA ICE were not validated within a deviation of a maximum of 10% when compared to the data from Uppsala kommun Sport- och rekreationsfastigheter AB. Hence, the results were analyzed on a general level, which showed that there was a greater need for heating during wintertime, with certain peaks during the coldest months, whereas the cooling is maintained at a relatively stable level throughout the year, but with a slightly greater need in the summer. Further on, there was an identified surplus energy from the ice rinks, in terms of waste heat from the refrigeration systems. During the summer there was a greater amount of surplus heat generated, caused by the greater cooling demand. Due to not being able to validate the models, complementary calculations of the yearly surplus heat were made with data from Uppsala kommun Sport- och rekreationsfastigheter AB. The surplus heat was 1 200 MWh for buildings A and B, 497 MWh for building C and 1 492 MWh for the bandy arena. No surplus cold was identified within the ice rinks. The suggested solution for sharing the surplus energy is to implement seasonal thermal storage, due to the similar characteristics in heating and cooling demand for the ice rinks. The stored surplus energy could cover the ice rink’s peaks in heating demand during winter, which is an energy-efficient way would reduce purchased heat from the district heating grid. For further studies, it is of great interest to identify the possibilities of implementing a distribution system similar to the fifth generation district heating as well as seasonal storage, to possibly enable a direct share of energy between all the buildings within the sports field.

This independent degree project has been implemented on behalf of FVB Sverige AB in collaboration Sundsvall Energi AB with the initial purpose of mapping manufacturers of hot water driven absorption chillers. After that, several technical solutions are examined to manage the peak load of a theoretical object which cannot produce the cooling power required with only an absorptions chiller, due to limitations in the district heating supply. The market study has shown that the supply of absorption chillers with drive temperatures of 70–90˚C is limited to a few manufacturers. World Energy offers a unit with drive temperatures of 70 ˚C and efficiency (COP) of 0,4. Due to limitations of district heating flow, a unit with drive temperature of 85 ˚C and efficiency of 0,77 is chosen. The technical solutions are dimensioned for a building with a peak power of 264 kilowatt, where the required peak load ranges from 31 to 39 kilowatt. The technical solutions examined are a solar collector system, tap water heat exchanger, and a conventional compressor driven chiller. The solar collectors are dependent on location but use no refrigerants that are affected by the F-gas regulation. The tap water solution consumes large flows of tap water, but the installation is simple. The conventional chiller is not location dependent but uses ozone degrading refrigerants and has a high cost of operation. From an economic perspective the technical solutions are equally profitable with a present net value of approximately 500 000 SEK and pay-back of 13 years. The examination has also shown that the present value is one million crowns in sales of heat and building after a ten-year period. In conclusion the conventional chiller has the biggest prerequisites to be used as a standardised solution for buildings with a bigger cooling load. Based on the technical and economical conditions.

La thèse étudie le rôle que les centrales nucléaires pourraient jouer dans la décarbonisation des secteurs du chauffage en Europe et en France. Un réacteur nucléaire est d’abord une source de chaleur à longue durée de vie qui peut produire de l’électricité grâce à un turboalternateur. Mais il peut également être utilisé en mode cogénération en produisant à la fois de l’électricité et de la chaleur. Cette option présente plusieurs avantages dont celui de fournir une chaleur exempte d’émissions de gaz à effet de serre (GES) et celui d’offrir de la flexibilité au réseau électrique.Aujourd’hui, l'exploitation la plus courante des centrales nucléaires est la fourniture exclusive d’électricité. Cependant, cela entraîne le rejet dans l'environnement de grandes quantités de chaleur issues de la conversion en électricité. Le transfert d'une partie de cette chaleur aux puits industriels ou aux systèmes de chauffage urbain à proximité réduirait la consommation de combustibles fossiles et les émissions de GES. Si cette chaleur venait en substitution de combustibles fossiles importés, cela permettrait également d'améliorer l’indépendance énergétique, favorisant ainsi la stabilité des prix à long terme. / The Ph.D. Thesis studies the role that nuclear plants could play in decarbonizing the European and French heating sectors. A nuclear power plant is basically a thermal plant that convert the nuclear heat into electricity using a turboalternator. But it could also be used in a cogeneration mode producing simultaneously power and heat. The latter offers many advantages including the low carbon profile and the ability to provide flexibility to the power grid.The most widely spread operation of nuclear plants today is electricity only production, which imply the dumping into the environment a large amount of heat that has not been converted to electricity. Transferring part of this heat to nearby industrial sinks or district heating systems would reduce fossil fuel consumption and greenhouse gases emissions. If this heat is replacing imported fossil-fuels that would also improve energy self-sufficiency, favouring long-term price stability.

Huvudsyftet med denna studie är att förstå om ett säsongsmässigt autoregressivt integrerat rörligt genomsnitt (SARIMA) -metod pålitligt kan förutsäga extrem variation i värmelaster för en fjärrvärmestation. Genom extrem variation ser vi på den maximala och minsta värmebelastningen per dag mätt i megawattstimmar. Avhandlingen bygger på standardimplementering av SARIMAX och utför en rutnätsökning efter de mest lämpliga parametrarna. Prognoser kan genereras från tidsserier i syfte att uppskatta förväntad energiförbrukning i en fjärrvärmestation. Frågan som ställs är: Hur tillförlitlig är SARIMAX-modellen för energibehov i en fjärrvärmestation? För att besvara studiens fråga designas och genomförs experiment med hjälp av ett dataset från verkliga mätningar. Datasetet studerades och analyserades med hjälp av undersökande dataanalystekniker som kommer med statistiska paket implementerade i en pythonmiljön, som kan användas som ett statistiskt program. Uppgifterna är uppdelade i två säsonger, sommar och vinter. Där den explorativa analysen av datasetet visar att modellen måste ta hänsyn till den starka veckocykeln med data. Så att korrelationen mellan utetemperaturen kan användas för att förbättra förutsägelsen. Fininställning och tillämpning av SARIMAX och Prophet för förutsägelser genererar data i form av diagram som visar hur tillförlitlig modellen är för förutsägelse. Resultaten visar att SARIMAX-modellen presterar bättre under vintermånaderna och sämre under sommaren. Baserat på dessa resultat antyder avhandlingsstudien att SARIMAX-modellen är mer tillämplig under vintermånaderna där förutsägelsen är mer tillförlitlig. Jämförelser med Prophet modellen indikerar lovande resultat och att vidare forskning borde föras för denna modell. Dessa resultat kan vara till hjälp för industrin som förser samhället och konsumenterna med fjärrvärme. Det hjälper till att förutse hur mycket energiförbrukning som används där industrin kan använda den för att reglera mängden fjärrvärme, för att ytterligare hjälpa ekonomin och miljön. / The main objective in this study is to understand if a Seasonal Autoregressive Integrated Moving Average (SARIMA) method can reliably predict extreme variation in heat loads for a district heating substation. By extreme variation we look at the maximum and minimum heat load per day measured in megawatt hour. The thesis relies on standard implementation of SARIMAX and performs a grid search for the most suitable parameters. Forecast can be generated from time series with the purpose of estimating expected energy consumption in a district heating substation. The question addressed is: How reliable is the SARIMAX-model for energy demand in a district heating substation? To answer the study’s question, experiments are designed and conducted using a dataset from real measurements. The dataset was studied and analyzed using exploratory data analysis techniques that come with statistical packages implemented in the python environment, which can be used as a statistical program. The data is separated into two seasons, summer and winter. Where the explorative analysis of the data shows that the model needs to take in account the strong weekly cycle of data. Also the correlation between the outside temperature can be used to improve prediction. Fine tuning and applying SARIMAX and Prophet for predictions generates data in the form of graphs and tables which shows how reliable the SARIMAX model is for prediction. Results show that the SARIMAX model is performing better during winter months and worse during summer. Based on these results, the thesis study suggests that the SARIMAX-model is more applicable during winter months where prediction is more reliable. Comparison with the Prophet model indicates promising results and that further investigations should be made into this model. These results can be of help to the industry that supplies the community and consumers with district heating. It helps by predicting how much energy consumption is used where the industry can use it to regulate the amount of district heating, to further help the economy and environment.

District heating and geothermal heating are in present times two established heating systems that are often compared against each other. The purpose of this work is to describe which factors influence the choice of heating system during the planning stage and what the costs are for each system. In this paper, a typical house model has been developed and used as a basis for the comparison of both systems. The comparison has been made in the form of energy calculations in the energy calculation program BV2, where heat requirements and regulatory requirements for energy performance have been compared in different geographical areas in Sweden. Furthermore, cost calculations have been carried out based on the energy calculations' results, where investment costs and annual costs have been set against each other. The result of the work shows how the measurement of energy performance differs from the actual amount of purchased energy due to geographical conditions. In the southern parts of Sweden, where the geographical correction factor is below 0, consumers are penalized by raising the primary energy number, unlike the northern parts where the primary energy number is instead lowered. Based on the cost calculations, it can be concluded that district heating, when available, is more economically advantageous in the short term. Geothermal heating on the other hand is a more profitable alternative in the long run. / Fjärrvärme och bergvärme är idag två etablerade värmesystem som ofta ställs mot varandra. Syftet med det här arbetet är att redogöra vilka faktorer som påverkar valet av värmesystem under projekteringsstadiet och vilka kostnaderna som finns för respektive system. I arbetet har en typisk husmodel tagits fram och använts som grund för jämförelsen av båda systemen. Jämförelsen har dels gjorts i form av energiberäkningar i energiberäkningsprogrammet BV2 där värmebehov och myndighetskrav på energiprestanda har jämförts i olika geografiska områden i Sverige. Vidare har kostnadsberäkningar genomförts utifrån energiberäkningarnas resultat där investeringskostnader och årliga kostnader har ställts mot varandra. Resultatet av arbetet visar hur måttet på energiprestanda skiljer sig från den faktiska mängden köpt energi på grund ut av geografiska förhållanden. I de södra delarna i Sverige där den geografiska korrigeringsfaktorn understiger 0 straffas konsumenter genom att primärenergitalet höjs, till skillnad mot de norra delarna där primärenergitalet istället sänks. Utifrån kostnadsberäkningarna kan man dra slutsatsen att fjärrvärme, när den finns tillgänglig, är mer ekonomiskt fördelaktigt på kort sikt. Bergvärme å andra sidan är ett mer lönsamt alternativ på lång sikt.

Rapid growth of digitalization has urged Data Centres (DC) to be more energy efficient by recovering waste heat from server racks that would otherwise be wasted. This techno-economic study is focused on upgrading low temperature waste heat from typical Air-Cooled DC for District Heating Network (DHN) market in Stockholm region. The methodology is carried out by four system configurations that are experimented with different historical electricity data, impacts of climate change with simulated weather data, and variations in DHN temperature as the heat supply scenario development. The results show that DC configuration with combination of both free-cooling and waste heat recovery can foster techno-economic benefits by reducing cooling consumption by 55.6%, compared to DC configuration with free-cooling only; and further lowering Power Usage Effectiveness (PUE) from 1.95 to 1.52. Lifecycle Operational Expenditure (LCO) has also been used as the economic indicator to represent the maximum initial investment that data centre should accept when deciding to recover the waste heat to the DHN. Moreover, the new technical Key Performance Indicators (KPIs) were introduced to support the decision-making in the supply of recovered waste heat to DHN. The electricity price was further identified to have greater impact than the effect of climate change for the overall techno-economic performance. On one specific hand, heat supply with Price-Limit scenario concluded that 40.18% of available waste heat from DC is not profitable should it be injected to DHN in the case of low electricity price. In the case when the electricity price is high, the amount of waste heat not injected to DHN increases to 58.57%. / <p>The thesis defense presentation was held digitally on Zoom on June 19th 2023 at 09.00 CEST</p>

4th generation district heating (4GDH) and varying the indoor temperature to store heat are both important concepts that can make it easier to implement more renewable energy and reduce costs of heating. This study looks at these concepts from a customer perspective using one building and looking at how energy can be stored and the performance of 4GDH. Low temperature heat sources from industry, supermarkets, and datacentres are used in combination with heat from a combined heat and power plant to get the required heating. A heat pump has also been modelled as a part of the 4GDH structure. In addition to looking at heat storage in 4GDH a scenario with direct electric heating has also been evaluated. In conclusion 4GDH has lower operating costs than 3rd generation district heating, but it is not worth varying the indoor temperature to store energy when using 4GDH. It is, however, profitable to vary indoor temperature if direct electric heating is used.