This thesis summarises the outcomes of a Big Data analysis, performed on a set of hourly district heating energy consumption data from 2012 for nearly 15 000 buildings in the City of Stockholm. The aim of the study was to find patterns and inefficiencies in the consumption data using KNIME, a big data analysis tool, and to initiate a retrofitting plan for the city to counteract these inefficiencies. By defining a number of energy saving scenarios, the potential for increased efficiency is estimated and the resulting methodology can be used by other (smart) cities and policy makers to estimate savings potential elsewhere. In addition, the influence of weather circumstances, building location and building types is studied. In the introduction, a concise overview of the concepts Smart City and Big Data is given, together with their relevance for the energy challenges of the 21st century. Thereafter, a summary of the previous studies at the foundation of this research and a brief theory review of less common methods used in this thesis are presented. The method of this thesis consisted of first understanding and describing the dataset using descriptive statistics, studying the annual fluctuations in energy consumption and clustering all consumer groups per building class according to total consumption, consumption intensity and time of consumption. After these descriptive steps, a more analytical part starts with the definition of a number of energy saving scenarios. They are used to estimate the maximal potential for energy savings, regardless of actual measures, financial or temporal aspects. This hypothetical simulation is supplemented with a more realistic retrofitting plan that explores the feasibility of Stockholm’s Climate Action Plan for 2012-2015, using a limited set of energy efficiency measures and a fixed investment horizon. The analytical part is concluded with a spatial regression that sets out to determine the influence of wind velocity and temperature in different parts of Stockholm. The conclusions of this thesis are that the potential for energy savings in the studied data set can go up to 59% or 4.6 TWh. The financially justified savings are estimated at ca. 6% using favourable investment parameters. However, these savings quickly diminish because of a high sensitivity on the input parameters. The clustering analysis has not yielded the anticipated results, but they can be used as a tool to target investments towards groups of buildings that have a high return on investment.

District heating is an efficient way to integrate renewable energies in the energy mix. In the French region Ile-de-France, district heating and renewables have known strong developments for several years, and they are expected to grow much more in the future. The expansion of renewable energies depends partly on their competitiveness compared to fossil fuels, which is related to public subsidies, and on the spread of district heating networks in the region. Thus, it could be assess what is the future business model for district heating based on renewables in Ile-de-France. The data at the disposal of ADEME, the French agency for environment and renewable energies, show that district heating systems based on biomass could soon become more competitive than fossil fuels, whereas systems based on geothermal heat have fairly high costs. Yet, geothermal heat is more developed than biomass, and is expected to reach the targets set by the regional action plan for 2020, on the contrary to biomass. Though the increasing competitiveness of renewables will cut the necessity of public subsidies, the difficulty to reach some regional targets might mean that further actions should be implemented. From the energy operators’ point of view, the sector of district heating will surely grow considerably and therefore represent a large potential of development for those companies.

The heat demand in Sweden has stagnated and district heating companies must take action to sustain in the market. Based on this background this study combines a PEST and SWOT analysis to produce a basis to suggest general strategies suitable for district heating companies in southern Sweden. The analysis found that both investments into activities outside of the heating market, as well as further development of current systems, are viable options. Increasing the awareness and knowledge about district heating companies was also identified as a factor that could entail several benefits.

Energy efficiency of district heating systems is of great interest to energy stakeholders. However, it is not uncommon that district heating systems fail to achieve the expected performance due to inappropriate operations. Night setback is one control strategy, which has been proved to be not a suitable setting for well-insulated modern buildings in terms of both economic and energy efficiency. Therefore, identification of a night setback control is vital to district heating companies to smoothly manage their heat energy distribution to their customers. This study is motivated to automate this identification process. The method used in this thesis is a Convolutional Neural Network(CNN) approach using the concept of transfer learning. 133 substations in Oslo are used in this case study to design a machine learning model that can identify a substation as night setback or non-night setback series. The results show that the proposed method can classify the substations with approximately 97% accuracy and 91% F1-score. This shows that the proposed method has a high potential to be deployed and used in practice to identify a night setback control in district heating substations.

This thesis aims to investigate if the hourly heat load consumptiondata can be used to approximate the daily consumptions patterns forbuildings connected to Göteborg Energi’s district heating network. Theapproximated data shall act as foundation for dimensioning of thedistrict heating network. In this work, it is studied how theconsumption approximation are due to changes in the outdoortemperature between different years.The aim is to develop an approximation model for hourly heat loadpatterns, heat output, water flow and return temperature from thedistrict heating substations of individual buildings regardless ofbuilding types. The approximation methods used in the hourlyapproximation model is multiple ridge regression. Regression trees areused to define breaking points such as the building balance pointtemperature from the consumer heat load pattern. Two separateregression intervals were defined based on breaking points from theregression tree. Outdoor temperature data, solar radiation data,weekday and weekends data used as predictors.The approximation model is evaluated against a reference model usingthe daily mean heat load consumption data. Evaluation between themodel and reference is made on six different building and buildingtypes during the outdoor temperature of -16, which is the designoutdoor temperature of the district heating system of Göteborg Energi.The approximated maximum heat output and water flow during the daywhere 18 % and 10 % above the approximated daily mean. Theapproximated return temperature where 43-51 °C compared to the dailymean of 42 °C for a warm year and 47-52,5 °C compared to 50 °C dailymean for a cold year.The hourly approximation model where able to capture the heat loadpatterns of different building types. However, higher demands on dataquality needs to be addressed to ensure the use of the hourlyapproximation model. / I detta examensarbete har en undersökning angående värmelastapproximationer baserade påtimupplöst kundlastdata gjorts. Värmelasterna som approximerades var värmeeffekt,vattenflöde och returtemperatur. Data för utomhustemperatur, helg och vardag samtsolinstrålningsdata har använts för att kunna approximera värmelasterna. Resultat avapproximationer har visualiserats i relation till utomhustemperaturen och har utvärderats fördimensionerande utomhustemperatur. Utvärdering gjordes på olika byggnader ochbyggnadstyper. Resultat av approximationsmodell med timupplöst kundlastdata utvärderadesmot modell baserad på dygnsmedeldata. Modellerna testades för två olika år med skildautomhustemperaturer, ett kall-år och ett varm-år.Resultat visar att det är möjligt att fånga den timvisa värmelasten hos enskilda kunder och skulleinnebära ett bättre underlag vid dimensionering. Detta då högsta värmelasten under ett dygnskiljer sig från dygnsmedellasten. Att implementera modell med timdatat ökar känsligheten imodellen och ställer högre krav på den inhämtade kundlastdatat. Mätare i fjärrvärmecentralerbör ses över för säkerställning av god mätupplösning och mätprecision.

Den globala uppvärmningen är en stor utmaning för världen att hantera och därför har länder som Sverige och unioner som EU kommit överens om olika klimatmål. Fram till 2020 är planen att utsläppen av växthusgaser skall sänkas med 20% jämfört med nivåerna 1990 och sen 2050 skall det reduceras med 80%. För att kunna möta dessa miljömål måste energiproduktionen inom EU-länderna bli mer miljövänlig. Ett sätt att producera sådan energi är med biobränslen vilket kan göras genom förbränning av biobränslena i en fjärrvärmeanläggning. Därmed blir det viktigt att alla energiproducenter strävar åt att gå mot en mer miljövänlig energiproduktion. Utöver att energiomvandlingen måste göras på ett miljövänligt sätt för att uppnå ett hållbart samhälle måste bra arbetsklimat också erhållas på anläggningarna. För om ett bra arbetsklimat inte infinner sig kan hälsan hos dem anställda riskeras med hälsoproblem som till exempel illamående och i värsta fall hjärtproblem. Dåligt arbetsklimat kan uppkomma på olika sätt men två exempel är vid för höga inomhustemperaturer eller dålig luftkvalitet. För att utvärdera hur bra ett inomhusklimat är finns olika typer av komfortindex, i denna studie har PMV-metoden använts för att utvärdera komfortnivåerna på Lersäters värmeverk som är en del av Kils Energi AB. Genom att samla in klimatdata inne i tre lokaler som används vid fjärrvärmeproduktionen kunde komfortnivåer för samtliga våningar beräknas. Dessutom har luftflöden i ventilationssystemet beräknats för vardera lokal och don för att säkerställa att anläggningen möter de rekommenderade kraven för ventilation från Arbetsmiljöverket. Ett av sätten att säkerställa ett bra arbetsklimat i lokaler är att ha ett väl fungerande ventilationssystem. Finns många olika tillvägagångssätt för att få en lokal väl ventilerad där vissa är energikrävande och vissa inte. Lersäters värmeverk har ett tilluftsventilationssystem som har pannan som utflöde ur pannhuset. PMV:s som beräknades fram i Lersäters värmeverk varierade kraftigt beroende på vilken lokal och vilken våning som undersöktes. När spjällen var stängda i pannhuset blev det beräknade PMV högre än 3 på våning 5 och 6 i pannhuset vilket är över det maximala värdet för PMV-metoden. Längre ner i pannhuset sjönk PMV till mer acceptabla nivåer där det gick mellan 1–2 för resten av anläggningen. Två olika fallstudier utfördes där olika fläktfrekvenser på ventilationssystemet och med öppna eller stängda spjäll i pannhuset. När spjällen var öppna blev komforten bättre i pannhuset. På våning 5 och 6 i pannhuset ökade komforten avsevärt när spjällen var öppna i jämförelse mot vid stängda spjäll. PMV minskade till runt 2 istället för 3–4 vid stängda spjäll. Pannhuset hade upp till 18 gånger högre luftomsättning än rekommenderade värden för inomhusklimat men stor del av denna luft blev stillastående på de lägsta våningarna där komforten blev god men på bekostnad av låga komfortnivåer på de övre våningarna. På dem två översta våningarna i pannhuset vid grundfallet var PMV till och med högre än det maximala värdet PMV-metoden normalt kan ge. En undersökning av vad de anställda tyckte om klimatet utfördes med hjälp av ett frågeformulär, se bilaga 3. Resultaten från formuläret visade att stora delar av mätresultaten stämde överens med dem anställdas åsikter. Personliga preferenser varierar alltid från person till person men genomsnittet bekräftade många av resultaten utöver komfortnivåerna i lagerlokalen 108an. I lagerlokalen 108an visade mätningarna en god komfort medan dem anställda ansåg den vara väldigt varm. Anledningen till denna skillnad är att lagerlokalen 108an påverkas mer av vilken säsong det är. För i beräkningarna visas bara resultatet från våren när utomhustemperaturen var låg medan de anställda bygger uppfattningen på hela året. Eftersom alla in- och utflöden för ventilationen sitter monterat på samma sida av pannhuset blir luftomrörningen dålig trots det aktiva ventilationssystemet som är monterat på anläggningen. Vilket rökanalyserna bevisar då bara ett par meter ifrån utflöden som spjäll eller insugen till pannan avtar lufttransporten mot dessa. Placering av utflödena i pannhuset är dessutom monterade på samma sida och dessutom sitter spjäll 1 och primär- och sekundärinsuget till pannan precis ovanför varandra. Detta leder till att trots höga flöden av friskluft tillgodoses in i lokalen blir utbytet av den förorenade luften bristfällig. För att förbättra komforten i pannhuset måste luftomrörningen förbättras. Det kan göras på flera olika sätt men till exempel genom att installera fler spjäll på väggarna och installera ställbara takluckor för att bättre kunna ventilera ut den varma stillastående luften runt taket. / The global warming is a big challenge for the world to handle and therefore have countries such as Sweden and unions agreed on different climate goals. Before 2020 the goal is to reduce the emissions of greenhouse gases by 20% compared to the levels at 1990 and then before 2050 reduce it to 80%. To achieve these climate goals the energy production within the EU gas to become more environmentally friendly. One way of producing such energy is with biofuels which can be done by burning biofuels in a district heating. Therefore, it’s important that energy producers try to become more environmentally friendly. To reach a more sustainable society the energy production must become environmentally friendly and make sure that the workers have good working conditions. Because if bad working conditions are not achieved the workers could get health problems, such as nausea and in worst case heart problems. Bad working conditions can be for example to high temperature indoors or poor air quality. To evaluate how good an indoor climate is there are different types of comfort index, in this study the PMV-method has been used to evaluate the comfort levels at Lersäters värmeverk which is a part of Kils Energi AB. Through climate data collection from inside of three different buildings that are used at the production facility could the comfort levels for all stories be calculated. Also, the flow of fresh air in the different rooms and from each diffuser was measured to secure that enough air was supplied to the buildings. One was of securing that good working conditions is achieved is to have a well-functioning ventilations system. There are many ways of making a building will well ventilated, there are some that require energy and some that don’t. Lersäters värmeverk have an active ventilation system which transport fresh air into the buildings through ducts. The calculated PMVs for Lersäters värmeverk varied heavily depending on which building and story that was evaluated. The calculated PMVs on Lersäters värmeverk varied largely depending on which building and what floor was evaluated. When the dampers were closed the PMV on floor 5 and 6 in the boiler room was higher than 3 which is normally the maximum value for the PMV-method. Further down in the boiler room the PMV decreased to more acceptable levels and was between 1 and 2 for the rest of the facility. Two different case studies were done where different frequencies on the ventilation system was used and if the dampers were open or closed in the boiler room. When the dampers were open the comfort was improved in the boiler room. On story 5 and 6 in the boiler room the comfort was greatly improved when the dampers were opened compared to when they were closed. The PMV went from above maximum to around 2. For the case studies different frequencies for the ventilation fan was tested and how open or shut dampers impacted the comfort levels.   When the dampers were open like in case 2 the comfort in the boiler room was improved. For story 5 and 6 in the boiler room the comfort was greatly improved with open dampers which was lowered to around 2 instead of 3-4 in the standard-case. The boiler room up to 18 times higher air intake than the minimum requirement for indoors climate but large part of this are became stagnant at the lower stories which made the comfort good there but at the cost of the comfort of the higher stories. With the comfort levels above maximum for the PMV-method at story 5 and 6 in the boiler room. A survey of what the employees at Lersäters värmeverk thought about the climate at the facility was done with a questionnaire. The results from the survey confirmed a lot of the calculated values for the comfort. But personal preferences always differ from person to person, but the averages confirmed the results except for the warehouse building called warehouse 108. In warehouse 108 the calculated values showed good comfort, but the employees thought it was a lot warmer. The reason for this difference is probably that this building is on a higher degree effected by seasonal changes and the employees evaluate the total comfort level for the building while the calculations only show results during the spring while the outdoor temperature is still low. All intake and outtake of air is located at the same side in the boiler room which makes the air circulation bad even though an active ventilation system is installed. Which the smoke analysis confirmed by noticing that the transport of air towards the outtakes reduces to almost zero just a few meters away from an air outtake. The placements of the outflows are also placed on the same side in the boiler room and damper 1 is placed right above the primary and secondary intake to the boiler. This led to that even though lots of air is supplied into the building the exchange between the contaminated air and the fresh air was far from good. To improve this exchange the air circulation must improve. This can be done in several ways, one way of doing it is the install more dampers and controllable hatches in the ceiling to be able to ventilate out the hot air around the ceiling.

För att möta problem med ökande klimatförändringar kan fjärrvärmen ha en betydande roll ur både en svensk och en internationell kontext. Samtidigt står svenska fjärrvärmebolag inför betydande utmaningar då värmepumpar blir ett allt vanligare val för att möta uppvärmnings- och tappvarmvattenbehovet, tillgången till avfall och biomassa som bränsle förutspås bli mer begränsad och byggnaders uppvärmningsbehov blir allt lägre. För att fjärrvärme ska fortsätta vara ett konkurrenskraftigt och hållbart alternativ för att möta uppvärmnings- och tappvarmvattenbehovet har konceptet fjärde generationens fjärrvärme (4GDH) tagits fram. 4GDH karaktäriseras av lägre nättemperaturer, fler förnybara energikällor för fjärrvärmeproduktion samt ökad integrering med andra delar av energisystemet. I detta examensarbete har dels möjligheter med att arbeta mot 4GDH i Borlänge Energis fjärrvärmenät undersökts och dels har potentialen med att uppnå ett hållbart energisystem genom att konvertera existerande svenska fjärrvärmenät till 4GDH undersökts. Examensarbetets fokus har primärt legat på den aspekt av 4GDH som innebär lägre nättemperaturer.  Beräkningar på Borlänges fjärrvärmenät visar att det finns fördelar med att sänka nättemperaturen i form av (1) ökad elproduktion i kraftvärmeverk (KVV), (2) effektivare rökgaskondensering samt (3) mindre värmeförluster. Störst kostnadsbesparingar och undvikta CO2-utsläpp erhålls genom effektivare rökgaskondensering följt av minskade värmeförluster. Den ökade elproduktionen i KVV medförde små kostnadsbesparingar och undvikta CO2-utsläpp i förhållande till tidigare nämnda faktorer. Simulering av Borlänges fjärrvärmenät i dagsläget och med 4GDH visade på att 4GDH skulle kunna leda till att en stor mängd drifttimmar undviks i Borlänge Energis avfallseldade hetvattenpanna samtidigt som fjärrvärmesystemet blir oberoende av fossila bränslen. Detta innebär stora undvikta CO2-utsläpp men grundat i att avfallsförbränning är en tjänst som fjärrvärmebolag får betalt för i dagsläget leder det totalt sett till en ökade bränslekostnader för Borlänge Energi.   Vid analys av kunder i Borlänges fjärrvärmenät valdes fem fastigheter ut som till stor del uppfyllde framtagna kriterier för att en fastighet skulle lämpa sig väl för 4GDH. Av dessa var tre fastigheter planerade byggnationer och två befintliga fastigheter. Av de presenterade tekniska lösningarna fanns endast tydlig ekonomisk lönsamhet, miljönytta och teknisk möjlighet i ett av fallen, där majoriteten av fastighetens fjärrvärmebehov kunde täckas av returvärme tack vare låga temperaturkrav. I två andra fall kunde ekonomisk lönsamhet och miljönytta konstateras men dessa krävde investeringar av externa aktörer för att tekniskt möjliggöras. I de övriga två fallen begränsades den ekonomiska lönsamheten och tekniska möjligheten av ett begränsat flöde i närliggande returledningar som föreslogs användas som framledning för lösningarna.  De långsiktiga fördelarna med 4GDH indikerade att det är ett angreppssätt man på sikt bör jobba vidare med i Borlänge eftersom det kan bidra till att uppfylla kommunala miljömål. Samtidigt visade de studerade kundfallen att det finns tydliga hinder för implementering av 4GDH trots att fastigheter bedöms väl lämpade för att nyttja lågtempererad fjärrvärme. Således drogs slutsatsen att 4GDH främst bör implementeras i form av större sekundärnät vilket kräver samordning av ett flertal aktörer och långsiktig planering. För att stödja Borlänge Energis arbete mot 4GDH togs en handlingsplan fram med rekommenderade åtgärder i dagsläget, på fem till tio års sikt och på längre än tio års sikt.  För att avgöra potentialen med 4GDH i svenska fjärrvärmenät generellt nyttjades resultat från beräkningar och simuleringar av Borlänges fjärrvärmenät för att simulera fyra typiska svenska fjärrvärmenät med olika produktionsmixar. Simuleringarna visade på att 4GDH i samtliga fall ledde till kostnadsbesparingar och undvikta CO2-utsläpp samtidigt som tillförseltryggheten ökade. Simuleringarna indikerade på att fjärrvärmenät där restvärme eller biomassa är de primära energikällorna främst drar fördel med 4GDH i form av minskade bränslekostnader medan fjärrvärmenät där avfall eller fossila bränslen är primära energikällor drar större fördel i form av undvikta CO2-utsläpp.  Resultaten från detta examensarbete visade att potentialen för att uppnå ett hållbart energisystem genom att konvertera svenska fjärrvärmenät till 4GDH är god. Beroende på vilken typ av svenskt fjärrvärmenät det är bör policys och styrmedel anpassas för att gynna en utveckling mot 4GDH, extra betydande är detta i fjärrvärmenät där avfallsförbränning står för en betydande del av fjärrvärmetillförsel. Generellt kan arbete mot 4GDH påbörjas på ett förhållandevis likvärdigt vis i svenska fjärrvärmenät, därför presenteras en generell metodik för hur svenska fjärrvärmebolag kan initiera en omställning mot 4GDH. / To face the emerging climate crisis, district heating could play an important role both in Sweden and internationally. Meanwhile, Swedish district heating companies are facing major challenges as heat pumps become more common to meet the heating and domestic hot water demand in buildings, the availability of waste and biomass as fuel is predicted to be limited and the heating demand of buildings is reducing. In order for district heating to maintain a competitive and sustainable alternative to meet the heating and domestic hot water demand in buildings, the concept of the fourth generation of district heating (4GDH) has been created. 4GDH is characterized by lower temperatures in the district heating network, more renewable energy sources used for heat production and increased integration with other parts of the energy system. In this master thesis, the possibilities with working towards 4GDH in Borlänge Energi’s district heating network has been evaluated. Also, the potential of achieving a sustainable energy system by converting existing Swedish district heating networks to 4GDH has been examined. The focus of the master thesis has primarily been on the aspect of 4GDH considering lower network temperatures.  Calculations show benefits with lower temperatures in Borlänge Energi’s district heating network such as (1) increasing electricity production in the combined heat and power plant (CHP), (2) more efficient flue gas condensation and (3) decreased heat losses. The largest reductions of costs and CO2 emissions are obtained from more efficient flue gas condensation followed by decreased heat losses. The increased electricity production in the CHP plant resulted in smaller reductions of costs and CO2 emissions compared to the above-mentioned factors. Simulations of a scenario where 4GDH is fully implemented in Borlänge, shows that 4GDH could lead to a lot of operating hours being avoided in the waste-fuelled hot water boiler and the district heating network being independent of fossil fuels. This means significant reductions of CO2 emissions but due to that waste incineration is a service that district heating companies gets paid for the total costs of fuel are increased.   When analysing customers in Borlänge Energi’s district heating network, five buildings were selected that largely fulfilled presented criterions for a building to suit well in a 4GDH system. Of these five buildings, three were planned buildings and two were existing. Of the presented technical solutions, there were only economic and environmental benefits with few technical barriers in one case. In this case, the heating and domestic hot water demand could mainly be covered by return heat owing to low temperature requirements. In two other cases, the economic and environmental benefits depended heavily on investments by external actors to be technically feasible. In the remaining two cases, the economic benefits and the technical feasibility was limited due to a limited flow in nearby return pipes which were proposed to be used as supply pipe to the buildings.  The long-term benefits with 4GDH indicated that it is an approach that should be continued with in Borlänge in the long term as it can contribute to reaching municipal environmental targets. However, the studied customer cases showed significant barriers to implementing 4GDH, although the buildings were assessed to be suited well for using low-tempered district heating. Thus, it was concluded that 4GDH should mainly be implemented by building larger low-tempered secondary networks. This requires coordination of multiple actors and long-term planning. To support Borlänge Energi’s work towards 4GDH, an action plan was presented with recommended measures today, in five to ten years’ time and in more than ten years’ time.  To generalize the results from Borlänge on a national level, the results from calculations and simulations of Borlänge Energi’s district heating network were used to simulate four typical Swedish district heating networks with different production mixes. The simulations showed that 4GDH in all cases led to reductions of costs and CO2 emissions and increased security of supply. The simulations indicated that district heating networks where residual heat or biomass is predominantly used mainly benefits from 4GDH through cost reductions, while district heating networks where waste or fossil fuels are predominantly used mainly benefits from 4GDH through reduced CO2 emissions.  The results of this thesis shows that the potential of achieving sustainable energy systems by converting Swedish district heating networks to 4GDH is high. Depending on the characteristics of the district heating network, policies and instruments should be adjusted to support a development towards 4GDH. This is especially important in district heating networks where waste incineration is a major source of the district heating supply. However, work towards 4GDH could generally be initiated in a relatively similar way in Swedish district heating networks. Therefore, a general method for initiating a transition towards 4GDH was presented

Fjärrvärme i dagens Sverige är ett väletablerat sätt att leverera värme för både industriell och privat användning. Med nästa generations fjärrvärmesystem vid horisonten kan förändringar av existerande fjärrvärmenät komma att bli vanligt förekommande. Trots att det inte är fullt aktuellt med den typen av renoveringar ännu så måste fjärrvärmenät ibland byggas ut för att hantera nya situationer som kan uppstå. För att få en god uppskattning om vad de nya situationerna kommer kräva, och potentiellt kosta, så är simuleringsmodeller ett användbart verktyg. Den här studien har granskat en kommande ökning av effektbehovet och en konsekvent ökning av den producerade värmen angående fjärrvärmesystemet lokaliserat i Malå. Granskningen genomfördes via etablering av en simuleringsmodell som baserats på metoder från tillgänglig litteratur. Empiriska värden användes både som indata till modellen och för feluppskattning. Två hypotetiska scenarier undersöktes där effektbehovet hos en industrikund antas dubbleras, ett som systemet ser ut idag och det andra med ett termiskt energilager i form av en ackumulatortank inkluderat. Simuleringssvaren gav en uppskattning av hur mycket effekt en ny produktionsenhet behöver kunna producera för att nå ett eftersökt mål. Dessa visade på att en ny produktionsenhet med en effekt av minst 10.50 MW är nödvändigt. Vidare så indikerade resultaten att installation av ett sådant energilager med den valda styrningen inte reducerar effektmagnituden hos en ny produktionsenhet. De visade dock på att införande av energilagret kan medföra en reduktion i antalet effektsvängningar som förekommer i systemet. Beroende på övrig konfiguration så minskades förekomsten av antalet effektsvängningar mellan 0.2 till 25.5 procent med ett energilager av den minsta undersökta volymen infört. / District heating in Sweden is a well established way of delivering heat for both industrial and private applications. With the next generation of district heating on the doorstep, changes of existing district heating networks may become a regular occurrence. Despite the fact that these kinds of reconstructions are not quite applicable yet, refurbishments of existing district heating networks are still sometimes necessary in order to deal with new prerequisites that may appear. In order to achieve a good estimation of what these new prerequisites will require and possibly cost, the usage of tools such as models for simulation are valuable. This study has evaluated a future increase of power demand and the subsequent expansion of the produced heat concerning the district heating network located in the city of Malå. The evaluation was carried forth by establishment of a simulation model which was based on present literature. Empirical data was used both as input and for error estimation. Two hypothetical scenarios were examined in which the power demand of an industrial customer is assumed to be doubled. The first represented the system as it is defined presently, while the other introduced a tank thermal energy storage to the system. The results of the simulation yielded an estimate of how much heat a new plant needs to produce in order to attain a set goal. These suggested that the necessary heat production in the new plant needs to be at least 10.50 MW. Furthermore, the results indicated that the inclusion of a thermal energy storage of this kind and with the defined priorities will not reduce the required size of a new production plant. However, they did indicate that the defined thermal energy storage may contribute to a reduction in the number of power fluctuations occurring in the system. Depending on other configurations, the frequency of the power fluctuations were reduced between 0.2 to 25.5 percent with the inlcusion of the smallest examined thermal energy storage.

Power plant performance can be assessed by the method of thermodynamic analysis. The goal of this thesis is to perform a thermodynamic analysis on the University of Massachusetts’ Combined Heat and Power (CHP) District Heating System. Energy and exergy analyses are performed based on the first and second laws of thermodynamics for power generation systems that include a 10-MW Solar combustion gas turbine, a 4-MW low pressure steam turbine, a 2-MW high pressure steam turbine, a 100,000 pph heat recovery steam generator (HRSG), three 125,000 pph package boilers, and auxiliary equipment. The University of Massachusetts’ CHP plant delivers all of the campus’ steam and nearly all its electricity to the more than 200 buildings and nearly 10 million gross square feet of building space. Two 20-inch main steam transmission lines connect the plant to the campus. On an annual basis the plant generates approximately 1,100,000,000 pounds of steam and 100,000,000 kWh of electric power. The plant has a SCADA (Supervisory Control and Data Acquisition) system. Rockwell Automation’s RSLinx OPC (Object Linking and Embedding for Process Control) server acquires data from up to 675 field instruments in the plant which is used for carrying out the analyses. The latest pollution control technologies, including advanced combustion turbine low NOx burners, advanced Selective Catalytic Reduction and Oxidation Catalyst pollution control technologies are employed in the plant. System efficiencies are calculated for a wide range of component operating loads. Factors affecting efficiency of the CHP district heating system are analyzed. In the analysis, actual system data is used to assess the district heating system performance, energy and exergy efficiencies and exergy losses. Energy and exergy calculations are conducted for the whole year on an hourly basis. Factors affecting efficiency of the CHP district heating system are analyzed and recommendations made to improve the operating efficiency. The results show how thermodynamic analysis can be used to identify the magnitudes and location of energy losses in order to improve the existing system, processes or components.

In Europe, the prices of natural gas and electricity reached an all-time high during 2022. An approach tomitigate these high prices is to expand the district heating systems in urban areas, this will reduceelectric load as well as to increase the power production in combined heat and power plants. Districtheating has been the dominant heat supply technology in urban areas in Sweden since the 1980s.However, as the number of low energy buildings are increasing, district heating distribution losses mustbe reduced to ensure cost-efficient consumer demand supply. This has led to the idea of the 4th-generation district heating which is characterized by low distribution temperatures.The aim of this study is to simulate low temperature distribution systems in a planned future city districtusing a Python based simulation tool and compare the results with a conventional system. Threedifferent types of low temperature distribution systems are investigated: 1) domestic hot water andspace heating separated, 2) apartment heat exchangers, 3) a cascading low temperature system.Focus is on simulating the distribution losses, distribution temperature and mass flow in the area, butthe scope of the analysis also includes an investigation of the effect of lower return temperatures to thecombine heat and power plant. The result indicate which type of system is most beneficial to implementin this specific area.With regards of distribution losses and temperature drop performs the low temperature distributionsystem with apartment heat exchangers better than the cascading system and the system withdomestic hot water and space heating separated. The mass flow is highly dependent of the temperaturedemand in the heating systems in the buildings and is higher for all low temperature distributionsystems compared to a conventional system.