The district heating system of Gävle will within a few years likely undergo changing routines in production and a rising demand for heat, which will increase the need for flexibility and availability in the production units. It is therefore relevant to study the economic potential of installing a thermal storage at the largest production unit in the system; Bomhus Energi. For storing heat over short time spans in district heating networks it is common to use heat accumulators. A model of the district heating system was created within an existing model structure. The system was simulated in scenarios where electricity price, electricity certificate price and heat demand were varied. For each scenario four different sizes of heat storages were tested. The reduction in production cost was used to calculate the payback time for each accumulator. None of the accumulators received a payback time shorter than the economic lifespan of 20 years. The second largest storage (4000 m3) received the shortest payback times, the best result being 23 years in the scenario of increased heat demand. The results for the largest storage (20000 m3) indicates on a large potential under certain circumstances. The study concludes that a heat accumulator would not be profitable under the investigated circumstances. However, it indicates that there are cases where a heat storage of the right size could be a good investment. For further study it is recommended to investigate the case of greater heat demand and accumulators with a volume between 4000 - 20000 m3.

Abstract The impinging jet ventilation's importance in providing better air distribution and energy-efficient operation, as well as both its heating and cooling flexibility potential cannot be overemphasized. This is because acceptable indoor air quality and its environmental conditions are essential to occupant’s wellbeing, comfort, productivity, and improved cognitive function. Poor air quality conditions could result in sick building symptoms (SBS) and several studies have investigated that the prevalence of sick building symptoms is associated with indoor air quality. Consequently, to the need for high ventilation effectiveness, the impinging jet ventilation system has been developed and applied in different types of buildings as a new ventilation strategy and concept within the last two decades. Therefore, it is important to continuously develop inventive air distribution systems such as IJV with a better location and terminal configuration of the supply device to adequately provide an acceptable indoor environment in an energy-efficient manner. This study aims at reaching a comprehensive understanding of the near field zone of an isothermal turbulent corner impinging jet in a room by using computational fluid dynamics (CFD) simulation tool. Thus, directly investigating the flow field involving the velocity magnitude, velocity decay, and spreading rate along the diagonal of the room.The cases carried out consist of 12 different three-dimensional modeled configurations (room) of the computational domain with the dimension 7.0 (L) x 7.0 (W) x 2.67 (H) m. The cases which comprised different aspects of diffuser geometry (triangle, quadrant, square), diffuser area, discharge height, and flow rates, used the RNG k-ε turbulence model to solve the turbulence flow.The result obtained, from the parametric study in all the cases was detailed to analyze the effect of the different flow rate, discharge heights, diffuser geometry, and its area on the velocity profile development, velocity decay, and spreading rate along the diagonal of the room. This study significantly shows the triangular geometries having greater velocity magnitude and velocity decay along all the line profile positions. Interestingly, a comparison between the quadrant and square geometry illustrates that their characteristics of generating a greater velocity magnitude depend on its discharge height. The result also demonstrated a decrease in jet velocity decay with an increase in jet discharge height. With similar jet spread at higher jet discharge, the square geometry exhibited a higher spreading rate at lower discharge height.

This master thesis examines if a PV system in “norra Djurgårdsstaden” (Stockholm) can be optimized by the addition of a battery storage system. Both in terms of increasing the usage of the produced PV energy and also (partly as a consequence) becoming more efficient and environment friendly. Simulations were run in both MATLAB and PVsyst. The simulations were based on measured data - PV production and consumption - and different scenarios were examined. Though the central aspect was to maximize the amount of PV energy used, simulations for peak shaving and a combination of the two were also examined.  The major differences between simulation in MATLAB and PVsyst were firstly, the fact that the input for consumption was monthly in PVsyst and hourly measurement (given by Incoord) was used in MATLAB and secondly, that different types of battery types had to be used. The battery type used in the MATLAB simulation was a NiMH battery from a company called Nilar. This battery type has the ability to be rejuvenated and thereby extend its lifetime. This type of battery did not exist as an option in PVsyst. Due to this the result of the simulation was not exactly the same. They were however similar enough to be useful; they showed similar patterns even at points of divergence.  Although the real estate was planned and built to be very energy efficient and environmentally friendly, the integration of a battery storage system was definitely able to optimize the PV system. Of the different integration options examined the most optimal was determined to be when the battery system was fed by the surplus energy from the existing PV system; after it has met momentary consumption needs. At the largest, battery storage system (10 batteries) the primary energy number (EPpet) decreased with almost 8 kWh/m2 - i.e. from 48,2 to just above40 kWh/m2. Self - consumption and self - sufficient was also positively affected by the battery storage with the former going from 59 to 77 % and the latter from 31 to 41 %. Furthermore with around 4 batteries in the battery storage system the EPpet decreased such as the real estate entered a higher order of environmental classification.  The battery system will always be an expense, however this expense is lessened by utilizing as much as possible of the PV energy, i.e. when the momentary consumption is met by the PV system before the surplus PV energy is directed to the storage in order to maximize self - consumption.

Biobränslen utgör 25% av Sveriges energitillförsel och majoriteten av dessa är träbaserade. Träpellets är ett biobränsle och i Sverige producerades 1,6 miljoner ton pellets 2018. Egenskaper hos pellets så som hållbarhet och energiåtgång för produktion testas ofta i en singelpelletspress. Då den totala energianvändningen för att pressa en pellet i en industriskalig matris innefattar tre energikrävande delmoment; komprimering, friktion och strömning. Strömning är då material som ligger över ytorna mellan presskanalerna, klacken, komprimeras och flytts ner mot konorna, samt då materialet som befinner sig i en kona deformeras när det trycks ner i presskanalen. Pelletering i en konventionell singelpelletspress innefattar enbart komprimering och friktion. Denna studie har fokuserat på att undersöka strömningsmomentets inverkan på den totala energianvändningen. För att undersöka detta har komprimeringsenergi, friktionsenergi, strömningsenergi samt den kraft som krävs för att strömningsmomentet ska påbörjas, Fflow, undersökts för 3 olika partikelstorlekar. Färsk gran med en fukthalt på 10% har pressats i olika matriser. Detta för att bestämma strömningens inverkan på den totala energianvändningen samt hur stor inverkan pressning av material som befinner sig runt inströmningskonan, på klacken, till presskanalen har på den totala energianvändningen. Partikelstorleken påverkar inte energianvändningen. Fflow var högre för tester i matris med klack jämfört med tester i matris utan klack. Detta ledde till att även komprimeringsenergin ökade. Materialet kring konöppningen påverkade pressningen så att den producerade pelleten blev 1 mm kortare, vilket gav en lägre friktionsenergi för dessa tester. Strömningsenergin stod för 43–57% av den totala energianvändningen. Energin som krävdes för den delen av strömningen där material runt inströmningskonan pressas stod för 35–52% av den totala energianvändningen. / Biofuels make up 25% of Sweden’s energy supply and the majority of biofuels used are made from wood. Wood pellets is one type of biofuel and in Sweden, 1.6 million tonnes of wood pellets were produced in 2018. Different pellet properties such as durability and energy use for production is often tested in a single pellet press. The total energy use for making a pellet in an industrial scale machine is the sum of the energy required for three different component sequences, compression, friction and flow. Flow is when the material that lies on the surfaces between the press channel openings is compressed and pushed downwards towards the coned openings and the materiel in the coned opening is deformed and pushed down to the press channel. Only compression and friction can be studied using a conventional single pellet press. Thus, this study focuses on the impact of the flow component on the total energy use for pelletizing. In order to do this, energy used for compression, friction and flow, as well as the power required for the material to enter the flow component, Fflow, has been studied for three different particle sizes. Fresh spruce with a moisture content of 10% has been pressed in different dies. With these pressings, the impact of the flow component, as well as the impact of pressing material located around the coned press channel opening on the total energy use was determined. Particle size did not affect energy use. Fflow was higher for pressings with material located on the surface around the coned opening, compared to pressings without. This resulted in an increased compression energy for pressings with material around the coned opening. The material located around the press channel opening affected the pelletizing so that the produced pellet was 1 mm shorter, which resulted in a lower energy use for the friction component. Energy used by the flow component made up over 43-57% of the total energy use. The part of the flow energy that is needed to compress the material around the press channel opening and move that material towards the opening stood for 35-52% of the total energy use for palletization.

No description available.

This Paper will focus on identifying, and look at potential ways of quantifying and valuing ecosystem services surrounding the cultivation of macroalgae. More specifically, the kelp species Saccharina latissima in the sea of Skagerrak at the Seafarm project. This paper is based on a literature review and case studies. Many ecosystem services have been identified and they were divided into the same four categories as in the Millennium Ecosystem Assessment report: provisioning, regulating, supporting and cultural services. To maintain a reasonable scope of this paper the most important ecosystem services were chosen. These ecosystem services were: All the provisioning services, climate and atmospheric regulation, regulation and mitigation of eutrophication and recreation and tourism. All the provisioning services, except reproduction of fish, are related to the amount of harvested kelp. The biomass can be quantified as dry weight (DW) with a relationship between DW and wet weight (WW). The method of quantifying climate and atmospheric regulation is in direct relation to the DW of the biomass. The study shows that the carbon sequestration on a cultivation site can be neglected and carbon stored in kelp used as food, fodder and fertilizer is released back into the atmosphere. Biomass used as biofuel prevents fossil fuel usage and should therefore be quantified. Provisioning ecosystem services are best valuated with the onsite valuation method. The carbon fixation value in climate and atmospheric regulation can be estimated with carbon credits and the oxygen production value can be estimated either with the assumption that it equals the carbon fixation value or with the replacement cost method. The value of mitigation of eutrophication can be estimated with CV and the value of recreation and tourism can also be estimated with CV but also with travel cost. / Den här rapporten kommer att fokusera på att identifiera, och titta på potentiella sätt att kvantifiera och värdera ekosystemtjänster kring odling av makroalger. Närmare bestämt kelparten Saccharina latissima i Skagerrak på Seafarm projektet. Många ekosystemtjänster har identifierats och de delades in i fyra kategorier: Försörjande, reglerande, stödjande och kulturella tjänster. För att upprätthålla en rimlig omfattning på projektet valdes de viktigast ekosystemtjänster ut. Dessa ekosystemtjänster var: Alla försörjande tjänster, klimat och atmosfärs reglering, reglering och begränsning av övergödning och rekreation och turism. Samtliga försörjande tjänster utom reproduktion av fisk, är relaterade till mängden skördade kelp. Biomassan kan kvantifieras som torrvikt (DW) med ett förhållande mellan DW och våt vikt (WW). Metoden för att kvantifiera klimat och atmosfär reglering är i direkt förhållande till DW av biomassan. Studien visar att kolbindning på en odlingsplats kan försummas och kol som lagras i kelp och används som livsmedel, foder och gödningsmedel släpps tillbaka ut i atmosfären. Biomassa används som biobränsle förhindrar dock fossil bränsleförbrukningen och bör därför kvantifieras. Försörjande ekosystemtjänster värderas bäst med direkta metoder som “on site valuation”. Kolet lagringens värde i klimat och atmosfär reglering kan uppskattas med utsläppsrätter och syre produktionsvärdet kan uppskattas antingen med antagandet att det är lika mycket värt som koldioxidlagringen eller med ersättningskostnadsmetoden. Värdet av begränsning av övergödning kan uppskattas med CV och värdet för rekreation och turism kan också uppskattas med CV, men också med resekostnadsmetoden.

No description available.

A Distributed Thermal Response Test is a method to determine ground properties such as thermal conductivity. Knowing the thermal properties of the ground is essential for designing and installing ground source heat pump and BTES systems. Knowing more accurate thermal properties can increase the efficiency of heat pumps by up to 20%, thus, contributing to energy efficiency and ultimately to sustainable development. This study introduces a convenient method for thermal response tests using heating cables as the single heat source. Once this new method is developed, it will make the implementation of DTRT techniques more versatile and inexpensive compared to the conventional DTRT, and it will create incentive for more investments in geothermal heat pump systems. This project is experimental in nature, hence, different equipment were tested and analyzed in order to find those that best suit this application. Several equipment such as certain types of heating cables have been tested and proven to be not optimal and some others, such as the selected power regulator, have resulted to be more adequate. The overall design initially proposed at the beginning of this study has been analyzed, modified and improved, and recommendations are given for future development. In conclusion, many obstacles have been overcome from the development process of DTRT with heating cables. A functional DTRT unit that uses heating cables has been built, however, it remains a challenge to improve the design in order to make it suitable for all potential borehole depths and various test requirements. / DTRT (”Fördelat ” termiskt responstest) är en metod som används för att beräkna markens termiska egenskaper såsom förmågan att leda värme. De termiska egenskaperna är av stor vikt när bergvärmepumpar ska installeras och speciellt för system med flera bergvärmepumpar som t.ex BTES. Om dessa egenskaper kan uppmättas med god noggrannhet kan det bidra till att ansenligt öka verkningsgraden för bergvärmepumpar jämfört med om testet inte genomförts, vilket då bidrar till högre energieffektivitet och hållbar utveckling. Detta projekt ämnar att skapa en ny, enklare metod för att utföra att ett termiskt responstest med hjälp utav värmekablar. När denna metod är fullt utvecklad kommer framtida test bli mer flexibla och kan utföras till en lägre kostnad jämfört med konventionella DTRT test. Vilket kommer skapa incitament för att investera i bergvärmepumps applikationer i framtiden. Projektet är experimentellt betonat och en ansenlig mängd tid har lagts på att finna rätt utrustning som passar syftet att finna en ny design för DTRT. Några av de ursprungliga ideerna har förkastats då de visade sig inte uppfylla våra syften, såsom värmekablarna. Däremot var effektregulatorn mer adekvat. Den icke adekvata utrustningen har analyserats och förslag till framtida utveckling ges. Sammanfattningsvis har en del hinder överkommits i utvecklingsprocessen för att realisera DTRT via värmekablar, men arbete återstår och designen bör utvecklas separat för olika borrhål, speciellt kabellängden är av essens.

I dagens globaliserade värld, samt genom urbaniseringen, har livsmedelsproduktionen i många fall upphört att ske i närhet till konsumenten. Detta har inneburit både ett minskat beroende av egen årlig skörd, då denna kan kompenseras av skörd från annat håll i världen, men också till komplexa frågor gällande bland annat etik och produktion av livsmedel som är i linje med den hållbara utvecklingen. Något som är fördelaktigt utifrån hållbarhetssynpunkt är en större konsumtion av fisk, då denna har en lägre påverkan på klimatförändringarna än det röda köttet. I och med en önskad ökad konsumtion av fisk diskuteras en omfördelning av konsumtion av fisk från fångad till odlad. Detta för att minska påverkan på de marina bestånden. Odling av fisk kan ske på diverse sätt. Två vanliga typer av odlingar är kasseodling och odling som använder sig av tekniken RAS, ”Recirculating Aquaculture System”. Kasseodling innebär ett öppet system där fisken odlas i vattendrag, sjöar eller hav medan RAS är ett slutet och kretsloppsbaserat system, ofta landbaserad. Syftet med arbetet var att undersöka odling av fisk utifrån ett hållbarhetsperspektiv, främst den ekologiska hållbarheten, där tekniken RAS jämförs med konventionell odling genom kasse. Förutom detta även involvera framtida perspektiv där en undersökning görs om hur en framtida försörjning av närodlad fisk kan se ut för en stad som Stockholm. Målet för arbetet var alltså att kartlägga dagens fiskesituation, åstadkomma en beskrivning av fiskodlingens för- och nackdelar samt visa på hur produktion av fisk genom RAS kan möta den ökade konsumtionen av fisk. Resultatet av studien visar att en RAS-anläggning har en högre energiförbrukning än en konventionell kasseodling. RAS-tekniken visar på fördelar som en hög kontroll av systemet som leder till exempelvis minskning av användandet av antibiotika. En RAS-odling är även lättplacerad samt tar lite mark i anspråk. Angående det framtida perspektivet genererades olika scenarios utifrån diverse rekommendationer och olika antagande gällande produktionskapaciteter. Det lägsta antalet RAS-anläggningar som behövdes för att möta behovet i Stockholm var 38 stycken, utifrån en produktionskapacitet på 1000 ton per år. En av slutsatserna var att när havsfisket minskar ökar intresset för odling av fisk. Befolkningstillväxten har även en bidragande roll för ökat behov av fisk och därmed också odling av fisk. Utöver detta visar RAS-odlingen på en möjlighet att optimera produktionen utifrån ett kretsloppstänk, vilket kan bidra till utvecklingsmöjligheter samt minimering av miljöpåverkan. Påföljande slutsats var att RAS-anläggningen hade högre energiförbrukning. Vad gäller näringsutsläppen krävs ytterligare utredning med fler mätdata. Denna utredning bör ske under samma förutsättningar och även utföras av tredje part. En vidare undersökning behövs även vad gäller utsläppstillstånden. Vad gäller framtidsscenariot krävs en högre produktionskapacitet för att en del av fiskbehovet i Stockholms län år 2030 ska ha sitt ursprung från RAS-odlingar. Täckande av behovet av fisk genom enbart RAS-anläggningarna anses orimligt. / The food production in today’s globalised world, together with urbanisation, has in many cases ceased to be in connection to the consumer. Not only has this led to a lower dependency on own food production, where harvest from elsewhere in the world can be imported, but also leading towards complex questions regarding ethics and production of food that meets sustainable development. A greater consumption of fish is something that is more advantageous when sustainable development is taken into account, thus fish have much less effect on climate change than red meat. Along with the desired increased consumption of fish a rearrange of the origin, from caught to farmed fish, is also discussed. Less effect on the marine stocks is favourable. There are different ways of farming fish. Two common ways are through farming by bag and the other way is farming with a RAS technique “Recirculating Aquaculture System”. Farming by bags means having an open system where the fish is farmed in watercourses, seas or the ocean, whereas RAS is a closed system that is often cycle based and also land based. The purpose of this report was to study farming of fish from a sustainable development point of view, mainly the ecological sustainability, where RAS is compared to a conventional farm with bags. Besides that, also include a study with a future perspective on how a supply of locally farmed fish may look like for a city like Stockholm in the near future. The aims for this report were therefore to map today’s fish situation, provide a description of the advantages and disadvantages of farmed fish and also to show if a production of fish through RAS is able to meet the increased consumption of fish. The results show that RAS has higher energy consumption than fish farmed by bags. The RAS technique shows benefits of having high control of the system, which leads to, for an example, lower usage of antibiotics. Farms using RAS are also easy to place and claims less land. From different recommendations and also different assumptions, regarding to capacity of production, a future scenario was generated. The lowest amount of farms using RAS, which are able to meet the need of fish in Stockholm, was 38 with a production capacity of 1000 tonnes per year. One of the conclusions was that when the capturing of fish from the ocean decreases the demand from farmed fish increases. The growth of the population is also a contributor to the higher demand of farmed fish. RAS optimises the production by using cycle based thinking, which can contribute to development and a lower impact on the environment. Following conclusion was that RAS had a higher consumption of energy. Regarding the leakage of nutrients, the conclusion was that there is a need for more data and further investigation. This investigation should be completed with the same conditions and also preferably made by a third party. The same thing applies regarding the permission of leaking nutrients. The future perspective shows that a higher production is needed if the demand for fish in Stockholm, by 2030, is to be met by farmed fish with RAS. RAS farms being the only source of fish for the demand in Stockholm is regarded as unreasonable.

Soil incineration is a relatively new subject that has usually had hazardous gas release problems. Incineration has been generally unsustainable. Incineration releases a wide array of gases hazardous to the environment and human health, such as polycyclic aromatic hydrocarbons, volatile organic compounds and dioxins. The studied so-called BAL process combusts soil to remove pollutants. Waste is removed in slag products and hazardous gases are crystallized. Almost no hazardous gases are released to the atmosphere. The purpose of this report was to optimize fuel use for the BAL process and to analyze the BAL process from a Sustainable Development perspective. oil, coal, peat and wood chips were examined. All fuels were viable. coal and oil required the least amount of fuel but the most amount of air. Peat and wood chips required less air but more fuel. No fuel was chosen as “best in any case”. Other optimization suggestions include: recycling of flue gases, Municipal Solid Waste as fuel and shape of combustion chamber. The BAL process was found to adhere to the Sustainable Development idea. The BAL process increases regional, economic and environmental sustainability. The results of this report may optimize the environmental sustainability of the BAL process even further.