The aviation industry needs to move towards a more sustainable future to achieve the climate goals set forth by the European Union (to reach a climate neutral economy by 2050), and in the recent past the interest in sustainable jet fuel has increased. In this report we compared different feedstocks and pathways for production of sustainable jet fuels from an economical, technical and environmental perspective for long-term implementation. A literature study was performed to gather data regarding fossil-based jet fuel, feedstocks for jet bio fuels and pathways for producing sustainable jet fuels. There are multiple ways of producing sustainable jet fuel and this report compares three different pathways: Hydroprocessed esters and fatty acids (HEFA), hydrothermal liquefaction (HTL) and electrofuel. Of these pathways, only HEFA has received certification for use as a jet fuel as of April 2020. The report also compared three different feedstocks: forest residues, used cooking oil and food waste. The comparison was done with a Pugh matrix - a criteria-based matrix - and was based on greenhouse gas (GHG) emission reduction, fuel readiness level (what stage of development the pathway is in), fuel production cost, yield and potential fuel output (how much of Sweden’s current jet fuel consumption can potentially be covered by each pathway/feedstock). The relevant data for the comparison was also gathered from the literature study. To put the comparison in a long-term context, the parameters where given a percentage of the total 100 points: potential fuel output – 30%, GHG-e – 30%, price – 20%, Yield – 10% and fuel readiness level – 10%. The study found that HTL with forest residues is most suitable for long-term implementation because of a high potential fuel output and low price. If the fuel production price of electrofuels can go down e.g. through government subsidies it would be another suitable alternative due to its massive potential in GHG emission reduction. / Flygplansindustrin behöver röra sig mot en mer hållbar framtid för att nå Europeiska Unionens klimatmål (att nå en klimatneutral ekonomi senast 2050), och under de senaste åren har intresset för hållbara flygplansbränslen ökat markant. I denna rapport sammanställde och jämförde vi olika produktionsvägar och råmaterial utifrån ekonomiskt-, tekniskt- och klimatperspektiv för långsiktig implementation. En litteraturstudie utfördes för att samla information om hållbara flygplansbränslen. Det finns ett flertal sätt att producera hållbara flygplansbränslen och denna rapport jämför tre olika produktionsvägar: Hydroprocessed Esters and Fatty Acids (HEFA), hydrotermisk förvätskning (HTL) och elektrobränslen. Av dessa har enbart HEFA godkänts för användning som flygbränsle (april 2020). Rapporten jämförde även tre olika råmaterial: biomassa från skogen, matlagningsolja samt matavfall ur ett svenskt perspektiv. Jämförelsen utfördes med en Pugh-matris som var baserad på: minskning i växthusgasutsläpp, teknisk mognadsgrad (hur långt i utvecklingen har produktionsväggen kommit), kostnaden för bränslet, effektivitet och potentiell bränslemängd (hur stor del av svenska jetbränslekonsumtionen kan vardera produktionsväg täcka). För att sätta jämförelsen i ett långsiktigt perspektiv vägdes jämförelseparameterna till: potentiell bränslemängd - 30%, minskning i växthusgasutsläpp - 30%, pris – 20%, avkastning – 10% och bränslet mognadsgrad – 10% av total 100 poäng. Studien fann att HTL med biomassa från skogen är lämpligast för en långsiktig implementation, på grund av dess höga potentiella bränslemängd samt ett lågt pris. Om priset för elektrobränslen kan minska genom till exempel statliga subventioner är även det ett intressant alternativ framförallt på grund av väldigt låga växthusgasutsläpp.

Fly ash particles from the combustion of coal together with disintegrated particles arising from iron-ore pellets result in accumulation of deposits on the refractory linings of the grate-kiln induration machine during the iron-ore pelletizing process. Deposit formation gives rise to decreased production efficiency, unscheduled shutdowns, high cleaning costs, and equipment failures. The deposits amass in the high-temperature regions of the induration furnace thus disturbing the flow of gas and pellets. Therefore, to tackle the above-mentioned issues, an understanding of deposit formation mechanism is of crucial importance. In contrast to pulverized-fuel-fired boilers, a grate-kiln process is characterized by a longer residence time, a highly oxidizing atmosphere, the presence of recirculating alkalis and disintegrated iron-ore pellet dust in the process gas. Given the foregoing, ash deposition phenomena in the grate-kiln process are much more complex compared to ordinary pulverized-fuel-fired boilers. This study was conducted with the objective of addressing the effect of disintegrated iron-ore pellet dust on deposit formation and the mechanisms behind deposition (slagging) in the grate-kiln process.Because of climate change and other pollution concerns, there is a desire to reduce on the combustion of carbon-intensive fuels. Moreover, as previously mentioned, the ash material from coal together with the disintegrated pellet dust cause deposition and slagging in rotary grate kilns, which can inflict severe production losses. For these reasons, it is of interest to study the potentials of co-firing coal with alternate fuels such as woody biomass. While the combustion of such woody biomass can be carbon-neutral, their effects upon deposition and slagging during co-firing with coal in a grate-kiln is unknown. Therefore, co-firing coal and woody biomass (softwood bark) was also thermodynamically investigated with particular emphasis on the effect of alkali recirculation upon deposition (slagging).To initiate elucidation of deposit formation during the iron-ore palletization process, a comprehensive set of experiments was conducted in a 0.4 MW pilot-scale pulverized-coal-fired furnace (ECF) where three different scenarios were considered as follows; Case1 (reference case): a high-rank bituminous coal was combusted without the presence of disintegrated iron-ore pellet dust. Case2: Natural gas was combusted together with simultaneous addition of hematite dust to the gas stream. Case 3: Coal was combusted together with the addition of hematite dust simulating the situation in the large-scale setup. Particles and short-term deposits were sampled from 3 positions of different temperature via a water-cooled rapid dilution sampling probe. Several characterization methods coupled with thermochemical equilibrium calculations (TECs) and viscosity estimations were employed to shed light on deposit formation and the mechanisms behind it in rotary kilns of iron-ore pelletizing plants. The most extensive interaction between hematite dust and coal-ash particles was observed in the coarse mode where a significant number of coal ash globules were abundantly found attached to the surface of the hematite particles. The morphology of the sharp-edged hematite dust particles was changed to smooth-edged round particles suggesting that hematite dust particles must have interacted with the surrounding aluminosilicate glassy phase. Consequently, the Fe content of the aforementioned glassy phase experienced a considerable increase. The short-term deposits during coal combustion (Case1) were highly porous in contrast to the high degree of sintering observed in the experiments with hematite addition (Case3). The incorporation of Fe into the aluminosilicate glassy phase (liquid fraction) decreased the viscosity and resulted in the formation of stronger (heavily sintered) deposits. The results suggested that hematite dust slagging tendency was independent of temperature, within the studied temperature-range (approximately 1100-1500 ºC), and required an auxiliary phase-provided by coal-ash- to form tenacious particles and cause slagging. In light of the experimental observations and TECs, a scheme of slag formation during the iron-ore pelletizing process was proposed.The TECs carried out for the woody biomass/coal blends indicated that that woody biomass is likely to increase the fraction of molten slag and exacerbate slagging when the molar ratio of Si/Ca > 2ii(equivalent to addition of more than 30 wt.% woody biomass, i.e. bark). However, when the abovementioned molar ratio is less than 2 (equivalent to addition of less than 10 wt.% bark), the fraction of molten slag increases by about 10 wt.% which does not seem to promote slagging extensively and can serve as a reasonable experimental blend.Overall, this work forms part of a wider study which aims at deepening the understanding of ash transformation phenomena during the large-scale pelletizing process. The findings from the current work are necessary to pave the path towards achieving the aforementioned goal.

Small-scale boilers significantly contribute to particle matter (PM) emissions, which adversely affect health and global warming. According to World Health Organization, particulate matter was ranked as the fifth significant parameter in premature death in 2015. Based on the Clean airpolicy package, which was established in 2013 by the European Commission, it is aimed to mitigate the emission from the combustion of energy sources to half by 2030. In Europe, small-scale biofuel boilers and domestic heating systems release 25% of total particulate matter annually. Thus, finding an economical method for small-scale cleaning flue gas is necessary. This research aims to obtain an efficient system to clean the flue gas from a small-scale biomass boiler. For this purpose, a setup has been built at Luleå University. The setup consists of a boiler (20kW), three heat exchangers, and a generator. The flue gas from combustion, which heats the water in the boiler, flows through the absorber and generator. In the absorber (packed bed wet scrubber), the flue gas is in contact with an absorption solution, and at the same time, particulate matter is cleaned from the flue gas. The solution is passed through a filter and is purified. A part of the solution flows through the generator, absorbed water is evaporated, and concentrated solution returns to the absorber. During this study, the stability of the solution in particulate matter collection was tested in the long-term running of the system (8 months), which did not show any deterioration in the solution ability for particle collection. The system efficiency in particulate matter size D50 (0.8-10 μm) collection efficiency was 42%. Also, the heat recovery of the system was improved by 18%. The effect of different forces on particulate matter in a wet scrubber was simulated by Ansys Fluent 19. 2 under different operation conditions. The governing forces on the particulate matter were studied, and the results showed that the concentration gradient has the highest effect on the collection of particulate matter. The effect of concentration gradient is explained as diffusiophoresis phenomenon. On the other hand, the temperature gradient (thermophoresis) did not strongly affect particulate matter collection. The influence of diffusiophoresis and thermophoresis on different particulate matter (PM) sizes under different flue gas velocities, temperatures, and water vapor mass fractions were simulated. Results demonstrated that increasing the flue gas velocity and particle size reduces the particle collection efficiency. The simulation result was validated against previous empirical models. In the next step, the effect of operation conditions on the PM collection efficiency was investigated. Based on the simulation results, the effect of water vapor concentration gradient, temperature gradient, and various heights of packed bed material in the absorber was studied experimentally. The measurements demonstrated that the water vapor concentration gradient greatly affects system PM collection efficiency. To improve the system’s efficiency, it is suggested to keep the temperature of the solution as low as possible and the absorption solution concentration at the highest applicable concentration. The obtained results showed that the absorber with a fully packed bed material has a better performance in particle collection. The obtained data can be used to build an efficient setup to clean the particulate matter released by small-scale boilers and would be interesting for companies that want to develop further the technology to be commercial for the market.

District cooling companies enforce a large penalty based on peak demands, which current cooling methods do not address properly. Building developers are exploring alternatives methods to reduce the said peak demands. The use of Ice Thermal Storage is an nontraditional method within the Scandinavian countries, but has shown to be a method to peak shave as well as load shifting in other regions of the worlds. The goal of the thesis was to "investigate the potential of ice thermal storage for cooling demand and peak shaving for Beridarebanan 4, 11, 77". The energy simulation was accomplished using the building performance simulator software IES VE. As inputs to the simulation, building data from the renovation project and corresponding weather data were used. The resulting simulation model was validated against renovated data with differences of 3,3% and 41,9% for the heating and cooling loads, respectively. The large discrepancy within cooling was determined to be weighted heavily by cooling strategy implemented within the building. When similar cooling strategies were implemented results were consistent with one another. This validation was investigated on a building, zone, and room level to look for consistency. The resulting simulated heating and cooling demands from IES VE were input into a then created ice thermal storage controller within MS Excel. In all, with the stable electrical and district cooling prices, a payback of 12 years was calculated for a 4,5 MWh, 6 hour storage ITS system. Results also show that for a 6 hour storage capacity,the controller exceeded the 1 000 kW price tier 4 hours out of the entire year, making it an ideal storage size. Current Swedish Electrical Market incentivize peak shaving rather than energy saving, accounting for nearly 80% of the yearly savings. The margin for earning more for the energy savings has negative consequences for potentially exceeding the 1 000 kW cooling threshold.

The supermarkets account for approximately 3% - 4% of the electricity consumption in the industrialisedcountries which makes them one of the main contributors to climate change. Food retail, similarly toother energy intensive industries requires deep changes that would reduce its negative environmentalfootprint. Online grocery (e-grocery), recording three-digit growth globally in the times of COVID-19pandemic, has the potential to disrupt the market and bring opportunities for energy intensity reduction.Brick & mortar retailers adapting to this trend not only experience technical challenges with orderfulfilment and last-mile logistics, but also they struggle to achieve profitability of e-grocery. Therefore,there is a need for guidance in this transformation. This thesis aims to help retailers choose the leastenergy intensive and profitable e-grocery configuration by comparing the emerging fulfilment models(in-store, omni store, dark store) and last-mile delivery options (click & collect, home delivery).The scope of this thesis includes a literature and market review, where an overview of e-grocery market,logistics, technologies, energy intensity and economics is given. The review is followed by methodologyexplaining the tools and assumptions used for analyses. Then, energy intensity analysis is performed whereenergy intensity per order is calculated using CyberMart software for three fulfilment models and twodelivery options. After that, the operating costs and profitability of e-grocery models is analysed. Finally,the results from analyses are discussed, concluded and recommendations for the retailers are given.The results of this thesis suggest that e-grocery may indeed reduce energy intensity of food retail but theenergy consumption has little impact on the operational costs of the e-grocers. Labour fulfilment andorder delivery costs optimisation play the biggest role in achieving profitability of online retail. Thus, it isrecommended that the retailers, along with the growing penetration of e-grocery, develop automatedfulfilment and click & collect solutions that would reduce the operational costs and allow for anincremental, yet future-proof adaptation to the e-grocery revolution. / Stormarknaderna står för cirka 3% - 4% av elförbrukningen i de industrialiserade länderna, vilket gör demtill en av de främsta orsakerna till klimatförändringarna. Livsmedelsbutiker kräver, på liknande sätt somandra energikrävande industrier, stora förändringar som kan minska dess negativa miljöpåverkan.E-handel av livsmedel, som har registrerat tresiffrig tillväxt globalt under tiderna förCOVID-19-pandemin, har potential att störa marknaden och ge möjligheter till minskning avenergiintensitet.Traditionell verksamhet som anpassar sig till denna trend upplever inte bara tekniska utmaningar medorderhantering och leverans till slutkund, utan de kämpar också för att uppnå lönsamhet. Därför finns detbehov av vägledning i denna omvandling. Denna avhandling syftar till att hjälpa återförsäljare att välja deminst energikrävande och lönsamma alternativen för e-handel av livsmedel genom att jämföra de nyamodellerna för orderhantering (in-store, omni store, dark store) och leveransalternativ till slutkund (click& collect, hemleverans).Avhandlingen omfattar en litteratur- och marknadsstudie, där en överblick ges över e-handel av livsmedel,logistik, teknik, energiintensitet och ekonomi. Studien följs av ett avsnitt om metodik som förklararverktyg och antaganden som används för analysen. Därefter utförs en analys av energiintensitet därenergiintensitet per order beräknas med hjälp av programvaran CyberMart för tre modeller förorderhantering och två leveransalternativ. Därefter analyseras driftskostnaderna och lönsamheten förmodeller för e-handel av livsmedel. Slutligen diskuteras resultaten från analyserna ochrekommendationerna till detaljhandlarna presenteras.Resultaten av denna avhandling tyder på att e-handel av livsmedel verkligen kan minskaenergianvändningen i livsmedelsindustrin men energiförbrukningen har liten inverkan pådriftskostnaderna för e-handlarna. Att optimera arbetet för orderhantering och kostnaden för leveransspelar störst roll för att uppnå lönsamhet för e-handeln. Det rekommenderas därför att detaljhandlarna,tillsammans med den växande andelen av e-handel, utvecklar automatiserad lösningar för orderhanteringoch click & collect som skulle minska driftskostnaderna och möjliggöra en stegvis, men ändåframtidssäker anpassning till e-handeln av livsmedel.

In the sector of food retail, supermarkets are common all over the world with their presence projected to increase further. They are also the most energy intensive amongst commercial spaces on an area basis, along with having direct emissions through refrigerant leakage. Energy efficiency and overall environmental impact of supermarkets are hence important areas of research. This study aims to investigate performance indicators for supermarkets through 3 case study stores using CO2 refrigeration. This is to be done by evaluating existing indicators and developing new ones based on field measurement data. Sales area as a primary performance indicator is commonly used for supermarkets. However, there is a need for additional indicators validated by reliable field data to further improve supermarket benchmarking as well as estimation of their energy demand. Total area, sales area, installed refrigeration capacity, outdoor temperature, opening hours and connected refrigeration load were studied, selected based on literature review and available data. The effect of outdoor temperature on energy demand yielded a trend which was consistent with the behaviour of climate dependent subsystems, heating and cooling. The total energy demand increases at high or low outdoor temperatures while remaining relatively constant between -4 and 15°C. Also, the impact of opening hours was studied by calculating the effect of closing of store on energy demand. A reduction of 36% upon closing of store was observed for one of the case studies. Normalised weekly opening hours (NWOH) was then formulated to account for the impact of varying opening hours on energy demand. Primary energy was also explored in the study for better comparability of energy use, accounting for both electricity and heat. Performance indicators based on opening hours and outdoor temperature can hence be explored using the foundation laid down in this study, through further research and reliable data across a wider range of climates and opening hours. / Livsmedelsbutiker är vanliga över hela världen och deras närvaro förväntas öka ytterligare. De är också bland de mest energikrävande kommersiella utrymmen per yta, dessutom har de direkta utsläpp genom köldmedieläckage. Energieffektivitet och övergripande miljöpåverkan från stormarknader är därför viktiga forskningsområden. Denna studie syftar till att undersöka prestandaindikatorer för livsmedelsbutiker genom fallstudier av tre butiker som använder CO2-kylning. Detta ska göras genom att utvärdera befintliga indikatorer och utveckla nya baserat på fältmätningsdata. Försäljningsområdet som primär prestandaindikator används vanligtvis för livsmedelsbutiker. Det finns dock ett behov av ytterligare indikatorer validerade av tillförlitliga fältdata för att ytterligare förbättra benchmarking för snabbköp samt uppskattning av deras energibehov. Total yta, försäljningsyta, installerad kylkapacitet, uteluftstemperatur öppettider och ansluten kylbelastning studerades, valda utifrån en litteraturstudie och tillgängliga data. Uteluftstemperaturs effekt på efterfrågan på energi visade en trend som överensstämde med beteendet hos klimatberoended elsystem, värme och kyla. Det totala energibehovet ökar vid höga eller låga uteluftstemperatur-värden medan det förblir relativt konstant mellan -4 och 15 °C. Dessutom studerades öppettidens inverkan genom att beräkna effekten av stängning av butik på energibehovet. En minskning med 36 % vid stängning av butiken observerades för en av fallstudierna. Normaliserade veckotider (NWOH) skapades sedan för att ta hänsyn till de olika öppningstidernas inverkan på energibehovet. Primärenergi undersöktes också i studien för bättre jämförbarhet av energianvändning, som står för både el och värme. Prestandaindikatorer baserade på öppettider och uteluftstemperatur kan därför utforskas med hjälp avgrunden som är lagd i denna studie, genom ytterligare forskning och en större mängd tillförlitlig data i andra klimat och med andra öppettider.

In this thesis computational fluid dynamics (CFD) was used for simulation of the indoor climate of low-energy buildings in cold climate. The heat consumption in newly built houses was reduced drastically. Along with the different classification systems for low-energy buildings the demand for the indoor climate has increased, which causes a need to investigate buildings even before they are built. Than CFD is of importance in studies of different heating systems and how new construction solutions can affect the indoor environment. The work focus was on investigating the computational setup, such as grid size and boundary conditions in order to solve the indoor climate problems in an accurate way and compare different heating systems. A limited number of grid elements and knowledge of boundary settings is therefore essential in order to obtain reasonable calculation time.The models show that radiation between building surfaces has a large impact on the temperature field inside the building, with the largest differences at the floor level. An accurate grid edge size of around 0.1 m was enough to predict the climate. Different turbulence models were compared with only small differences in the indoor air velocities and temperatures. To explore the viability of this approach, the indoor climate in a building was studied considering three different heating systems: an underfloor heating system, air heating through the ventilation system and an air heat pump installation. The underfloor heating system provided the most uniform operative temperature distribution and was the only heating system that fully satisfies the recommendations to achieve tolerable indoor climate set by the Swedish authorities. On the contrary, air heating and the air heat pump created a relatively uneven distribution of air velocities and temperatures, and none of them fulfils the specified recommendations. From an economic point of view, the air heat pump system is cheaper to be installed but produces a less pleasant indoor environment then distributed heating systems. The most widely used turbulence model for indoor CFD simulations, the k-ε model, has exhibited problems with treating natural convective heat transfer, while other turbulence models have shown to be too computationally demanding. One paper therefore studies how to deal with natural convective heat transfer for a radiator in order to simplify the simulations, reduce the numbers of cells and the simulation time. By adding user-defined wall functions, to the k-ε model the number of cells can be reduced considerably compared with the k-ω SST turbulence model. The user-defined wall function proposed can also be used with a correction factor for different radiator types without the need to resolve the radiator surface in detail. Compared to manufacturer data the error was less than 0.2% for the investigated radiator height and temperature.

Black liquor, a by-product from the Kraft pulping process is a highly viscous fluid consisting of approximately 30% water, 30 % alkali salts and 40 % combustible material. The alkali salts originating from the pulp making process need to be recovered in order for the pulp mill to be economical and to satisfy environmental regulation. Currently, the recovery takes place in a large boiler called Tomlinson recovery boiler named after its inventor. However, a more energy efficient way to recover the chemicals could be via gasification in a pressurized, entrained flow, high temperature gasifier. To demonstrate this technology a development plant (DP1) was built in 2005 by the technology vendor Chemrec. Since then, the plant has been running for more than 10 000 h and frequently been updated and optimized. As steps towards commercialization and scale–up different computational models of varying sophistication are used as design and optimization tools for the process. Still, the engineering tools can only provide sensible predictions if they are properly validated and verified. This licentiate thesis is concerned with validation of a comprehensive mathematical model based on Computational Fluid Dynamics (CFD) describing the gasification reactor and experimental investigations of the process characteristics in the DP1 gasifier. Paper A describes the system design and methodology for high temperature gas sampling during pressurized black liquor gasification. In this work a water-cooled gas sampling probe is installed in the hot part of the DP1 gasification reactor and several gas samples are withdrawn and analyzed. The experimentally obtained data in Paper A are then used as validation data for the CFD-model described in Paper B. In Paper C the obtained data from Paper A are thoroughly analyzed and the influence of reactor operation on producer gas composition is determined. In Paper D black liquor sprays from a gas assisted nozzle is experimentally investigated using high speed photography. Furthermore, the particle content in the cooled producer gas is measured using a particle sizing impactor. The obtained results in Paper D can be used to explain some of the observations in Paper A.

Increased concern about environmental problems has amplified the public`s interest inenergy usage. The improved subsidies for biomass, together with the rising energy priceshave made biomass a desirable product on the energy market. Energy intensive industries inthe field of wood and biomass now have nowadays an opportunity to decrease energyconsumption and to sell their biomass surplus on the energy market.This Licentiate thesis focuses on strategies to decrease biomass usage in sawmill industriesin order to increase their surplus biomass and increase their profit. This is done throughsystem analysis of sawmill industries in terms of mass and energy flows. The energyanalysis focuses on the drying kiln using psychrometric and thermodynamic relationships.State-of-the-art technologies, available on the market, have been studied to determine theirpossible effect on the total energy usage in the sawmills.This study was undertaken to determine the national use of energy due to sawmills and thepotential magnitude of improvements. Sawmills are important suppliers to the biomassmarket, since medium to large capacity sawmills contribute with 95% of the Swedish annuallumber (sawn boards) production (17.3 Mm3) with a lumber interchange of only 47%. Therest of the timber (unsawn logs) is transformed into biomass through the lumber productionprocesses. An essential part (12%) of the timber is used for supplying heat to the productionprocesses, mainly to the drying process which is the most time and heat consuming processin the sawmill. The main conclusions are that the heat demand for drying lumber in Swedishsawmills was found to be 4.9 TWh per year and the drying process can be made moreeffective by use of state-of-the-art technologies. Hence the internal use of biomass insawmills can be decreased, thereby increasing the biomass that can be sold to the marketand/or to generate heat and/or electricity, resulting in more profitable sawmills and asignificant increased supply of biomass to the market.It was also found that with available state-of-the-art technologies it is possible to recycle theheat in the evacuated air from the dryer, and if the recovered heat is used for heat sinksinside or close to the sawmill a large decrease of the energy usage can be achieved. If thetechnologies are implemented up to 5.56 TWh of equivalent biomass can be saved,depending on the technology, the specific sawmill conditions, kiln settings and dryingsystem operation. However, some of the considered technologies consume a substantialamount of electricity, so the economic benefit should be carefully evaluated.

In recent years, increased concern over global warming has put focus on the emissions of fossil CO2 into the atmosphere. Due to a strong relationship between the use of energy and the burning of fossil fuels, reducing society’s energy use has become increasingly important. In the energy intensive process industry, process integration is a field of research that has shown good results for decreased energy use in many industrial branches. This thesis is centred on the introduction of process integration to a new industrial branch for the field ‐ the mining industry. With an overall aim to introduce process integration as a tool for increased energy efficiency of Loussavaara‐Kiirunavaara AB (LKAB) in Kiruna, the application and development of process integration methods is presented. More specifically the thesis deals with process systems modelling by application of the MIND method (Method for analysis of INDustrial energy systems) and the optimisation of those models by MILP (Mixed Integer Linear Programming) optimisation. Among the results of this thesis are; the presentation of optimised operational strategy for utility boilers that can decrease fuel use with 7%, thedevelopment of a new method for facilitated multi‐period optimisation of dynamic systems and the proposal of a heat recovery installation in the mine ventilation system capable of decreasing the heating systems fuel use by 67%.