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The function of a flue-gas quench is to remove additional contaminants from flue-gas and to reduce the wastewater from a waste incineration plant. The aim of this degree project is to find how the system is affected by using a quench and what factors limits the performance. This is done by modelling and simulating a waste incineration plant in Aspen Plus. Data and plant schematics were obtained by a study visit to Mälarenergi Plant 6 situated in Västerås, Sweden, which were used as model input and for model validation. The results have shown that the amount of wastewater can be reduced by more than half compared to a plant without a quench. The heat produced in the condenser, when discharging water to the boiler, would be lowered by up to 20%. For systems with a quench present when more water was discharged to the boiler both the heat production and the pollutant capturing became better. However, the system has limits regarding the amount that could be recirculated, in the form of temperature limits in different parts of the system. In addition, if the heat load is low there is an insufficient amount of wastewater generated in the condenser to run the quench. In that situation, clean (fresh) water needs to be used instead. Using clean water is unwanted since the plant will then consume more resources while still producing less heat than a plant without a quench would.

Batteries are promising sources of green and sustainable energy that have been widely used in various applications. Lithium-ion batteries (LIBs) have an important role in the energy storage sector due to its high specific energy and energy density relative to other rechargeable batteries. The main challenges for keeping the LIBs to work under safe conditions, and at high performance are strongly related to the battery thermal management. In this study, a critical literature review is first carried out to present the technology development status of the battery thermal management system (BTMS) based on air and liquid cooling for the application of battery energy storage systems (BESS). It was found that more attention has paid to the BTMS for electrical vehicle (EV) applications than for stationary BESS. Even though the active forced air cooling is the most commonly used method for stationary BESS, limited technical information is available. Liquid cooling has widely been used in EV applications with different system configurations and cooling patterns; nevertheless, the application for BESS is hard to find in literature.To ensure and analyze the performance of air and liquid cooling system, a battery and thermal model developed to be used for modeling of BTMS. The models are based on the car company BMW EV battery pack, which using Nickel Manganese Cobalt Oxide (NMC) prismatic lithium-ion cell. Both air and liquid cooling have been studied to evaluate the thermal performance of LIBs under the two cooling systems.According to the result, the air and liquid cooling are capable of maintaining BESS under safe operation conditions, but with considering some limits. The air-cooling is more suitable for low surrounding temperature or at low charging/discharge rate (C-rate), while liquid cooling enables BESS to operate at higher C-rates and higher surrounding temperatures. However, the requirement on the maximum temperature difference within a cell will limits the application of liquid cooling in some discharge cases at high C-rate. Finally, this work suggests that specific attention should be paid to the pack design. The design of the BMW pack is compact, which makes the air-cooling performance less efficient because of the air circulation inside the pack is low and liquid cooling is more suitable for this type of compact battery pack.

In order to develop energy-efficient constructions all new buildings will be nearly-zero energy buildings by year 2021. A nearly-zero energy facility is a building with high energy performance and very low energy consumption, where the amount of energy that needs to be supplied to the building will largely originate from renewable sources that are often self-produced on site or nearby. On December 15, 2016 BFS 2016: 13 - BBR 24 was introduced with requirements for verification of the building's specific energy use. The new regulations for nearly-zero energy buildings will be introduced in two stages through BBR (A) and BBR (B). BBR (A) implies no aggravation of requirements, but introduces a new way of calculating the energy performance of the building measured in primary energy. Primary energy factors are introduced per energy carrier, where the energy carrier for electric heating receives a higher value then other energy carriers. A projected five-storey apartment building located in Sigtuna, Stockholm has been investigated and energy calculations and simulations have been carried out in the energy calculation program IDA Indoor Climate and Energy. Simulations have been carried out on a reference object, focusing on analyzing how the energy utilization of the building is affected by various actions. The measures investigated are energy supply and origin of this, changes in the building construction and technical systems. The result shows that with relatively small changes the required demands of close-zero energy buildings can be reached. Changes to the building construction through better exterior wall insulation, better U-values ​​of building constructions and increased efficiency of heat exchanger, make demands for near-zero energy buildings in BBR (B). With self-produced electricity via solar cells the primary energy for the building will be even lower. The hardest challenge comes for the electricity heated buildings which due to an increased primary energy factor, will get harder to meet the future requirements due to a higher demand level.

Handboken beskriver olika solfångarkonstruktioner och solvärmekretsens ingående komponenter och ger en grundlig inblick i ackumulatortankens konstruktion och funktion. I boken finns förslag på systemutformning, olika tekniska lösningar och hur systemen bör styras och regleras. Handboken beskriver i första hand utformning-lösning-styrning av kombinationen sol- och pelletsvärme, men tar även upp solvärme i kombination med vedpannor, värmedrivna vitvaror och värmepumpar. Värmesystem med vattenburen värme är utmärkta att kombinera med solvärme, men det är i de flesta fall enklare att få till bra lösningar vid nyinstallation, än vid komplettering av befintlig anläggning. När solvärme och pelletsvärme ska kombineras finns det många alternativ till systemutformning. Det är viktigt att vattenburna pelletssystem utformas korrekt och kombineras på rätt sätt med solvärme för att komforten ska bli hög och elanvändningen låg. Vattenmantlade pelletskaminer med ett vattenburet värmesystem är extra intressant i kombination med solvärme. När eldningen upphör i samband med att värmebehovet avtar kan solvärmen ta över. En generell slutsats är att konventionella svenska pelletspannor med inbyggd varmvattenberedning inte är lämpliga i kombination med solvärmesystem. Den typen av bränslepannor ger komplicerade systemlösningar, höga värmeförluster och det är svårt att åstadkomma en tillräckligt bra temperaturskiktning i ackumulatortanken om varmvattenberedning sker i pannan. Solvärme för varmvattenberedning kan vara ett enkelt och bra komplement till pelletskaminer som genererar varmluft. För solvärmesystem är det viktigt att kraftig temperaturskiktning erhålls när värmelagret laddas ur. Det betyder att ackumulatortankens (eller varmvattenberedarens) nedre vattenvolym ska kylas ner till temperaturer som ligger nära ingående kallvattentemperatur. Ackumulatortankens mellersta del bör kylas till samma temperatur som radiatorreturen. Vid design av solfångarkretsen måste överhettning och stagnation kunna klaras utan risk för glykolnedbrytning eller andra skador på värmebärare eller rörkrets (och andra komponenter i kretsen). Partiell förångning minskar risken för att glykolen skadas då solfångaren når höga stagnationstemperaturer. Solfångarens glykolblandning tillåts koka (förångas) på ett kontrollerat sätt så att endast ånga blir kvar i solfångaren. Vätskevolymen i solfångaren samlas upp i ett större expansionskärl och systemet återfylls när vätskan kondenserar. Dränerande solfångarsystem med enbart vatten är ett möjligt alternativ till konventionella solfångare. De kräver en större noggrannhet vid installationen, så att sönderfrysning undviks. Dränerande systemlösningar är relativt ovanliga i Sverige. Om solfångaren under senhöst-vinter-tidig vår kan arbeta med att förvärma kallvatten från 10 till 20 ºC erhålls en betydligt bättre verkningsgrad på solfångaren (och framför allt ökar värmeutbytet då drifttimmarna ökar väsentligt) än om radiatorreturen (som i bästa fall ligger på temperaturnivån 30 - 40 ºC) ska förvärmas. Därför bör radiatorreturen placeras en bra bit upp från botten i ackumulatortanken och tappvarmvattnet ska förvärmas i en slinga som börjar i tankens botten. Om det finns ett VVC-system måste systemet anslutas på ett speciellt sätt så att ackumulatortankens temperaturskiktning inte störs. En viktig parameter vid ackumulatortankens utformning är att värmeförlusterna hålls låga. Det är viktigt för att klara tappvarmvattenlasten med solvärme under mulna perioder sommartid (men också för att hålla energianvändningen låg). I moderna hus, där ackumulatortanken i regel placeras i bostaden, blir det en komfortfråga att undvika övertemperaturer i det rum där värmelagret placeras. En bra standard på isoleringen (med minimerade värmeförluster) kräver att det finns ett lufttätt skikt över hela isoleringen som dessutom sluter tätt mot röranslutningar. Ofrivillig självcirkulation i anslutande kretsar som kan kyla av och blanda om ackumulatortankens vattenvolym, bör förhindras med backventiler och nedböjning av rören i isolerskiktet eller direkt utanför tanken.

The geographically spatial and controlled distribution of fossil fuel resources, catastrophic global warming, and depletion of fossil fuel resources have forced us to integrate zero- or low-emissions energy resources, such as wind and solar, in the generation mix. These renewable energy resources are unexhausted, available around the globe, and free of cost. The advancement in wind and solar technologies has caused an appreciable decrease in installed the and global levelized costs of electricity via these sources. Therefore, the penetration of renewable energy resources in the generation mix can provide a promising solution to the above-mentioned problems. The aim of simultaneously reducing fuel consumption in terms of “Fuel Cost” and “Emission” in thermal power plants is called a combined economic emission dispatch problem. It is a combinatorial and multi-objective optimization problem. The solution of this problem is to allocate the load demand and losses on the committed units in such way that the overall costs of the generation and emission of thermal units are reduced, while the legal bounds (constraints) are met. It is a highly non-linear and complex optimization problem. The valve-point loading effect makes this problem non-convex. The addition of renewable energy resources (RERs) adds more complexities to this problem because they are intermittent. In this work, chaotic salp swarm algorithms (CISSA) are used to solve the combined economic emission dispatch problem. Chaos is used as an alternative to randomization for the tuning of the control variable to improve the trait of obtaining global extrema. Different test cases having different combinations of thermal, solar, and wind units are solved using the proposed algorithm. The results show the superiority of this study in comparison to the existent research results in terms of the cost of generation and emissions.

With the growing frequency and extent of extreme weather events, the resilient operation of multi-energy systems (MESs) has drawn attention nowadays. However, there is little study on the methodology with a set of key indicators to quantify the resilience of MESs with the consideration of the impacts of extreme weather. To address the problem, this paper proposes a framework to evaluate the time-dependent resilience of MESs considering energy interactions during extreme weather events, such as windstorms. Firstly, the multi-phase performance curve is utilized to describe the response behavior of MESs at different phases under the impacts of windstorms. Secondly, a service-based optimal energy flow model is developed to minimize the consequences caused by windstorms through the coordination among different energy subsystems. In order to model the chaotic failures and restoration of components, the Monte-Carlo simulation technique is applied. Furthermore, nodal resilience metrics for different energy carriers are proposed to quantify the resilience in MESs. Numerical studies demonstrate the capability of the proposed technique to quantify the resilience of MESs under windstorms. The results show that the resilience performance level of MESs can differ in different regions with the impacts of windstorms. The findings can provide a useful reference for system operators to constitute targeted resilience improvement measures.

As part of realizing national and European climate ambitions, it is imperative to bring about increased energy efficiency and consumption flexibility in the residential sector of the Swedish power market. In addition to governmental policy instruments to this end, market-based measures play an important role in making behavioral change in domestic electricity use happen. In light of the prevailing lack of incentives for residential consumers to save electricity and cut peak demand at times of physical and financial market constraints, the research studies that form the basis of this thesis have the aim of adding to the body of knowledge on policy instruments for the purpose of boosting behavioral change in residential electricity consumption. The research has accordingly contributed to the general statistics on residential electricity consumption, which constitute the starting point for policy instrument development, and augmented knowledge on the merits of residential demand response programs involving hourly settlements in power trading and demand-based, time-of-use tariffs in power distribution as well as graphic feedback on individual households’ electricity use by means of a statistics service provided over the Internet.

The overall results have shown that household behavior, together with physical factors such as heating systems, help explain the sizeable differences in electricity consumption among homeowners. Statistical analysis of variance has in this context proven to be an effective method for identifying key indicators of policy development. Power suppliers and electricity consumers as well as society as a whole have been found to gain substantially from hourly settlements in retail. To suppliers, the greatest benefits are associated with risk management, while the major advantage to customers is that they are provided with an opportunity to reduce their electricity costs. It has also been empirically demonstrated that electricity users are willing to adjust their consumption to a demand-based, time-varying distribution tariff. Households generally have a favorable attitude towards this type of distribution tariff, seeing as they indirectly have a positive impact on the environment. Providing households with feedback over the Internet on their individual electricity use and demand has been shown to contribute to an increased awareness and lead to energy efficiency in homes. Easy accessibility and simplicity have proven to be key success factors in this context. Combining conventional bar charts, color symbolism and historic feedback is expedient in this respect.

Elanvändningen i våra bostäder sker utan närmare eftertanke och reflektion. Återkopplingen avseende hushållens individuella elanvändning är i det avseendet mycket betydelsefull. I dagsläget är dock den förbrukningsinformation som hushållen har tillgång till mycket begränsad, i synnerhet i flerbostadshus. Syftet med projektet Visualisering av elanvändning i flerbostadshus är att utveckla och utvärdera designkoncept för individuell återkoppling till hushåll som bor i lägenhet. Designkoncepten avser en portabel display, en webbaserad statistiktjänst samt grafisk förbrukningsinformation på elräkningen. Det övergripande målet med projektet är en minskad och mer medveten elanvändning i flerbostadshus.

Utvecklingen omfattar displayens och statistiktjänstens funktioner och gränssnitt samt en ändamålsenlig formgivning av den grafiska återkopplingen på elräkningen. Utvärderingen omfattar de boendes användning och upplevelser av de produkter och tjänster som designkoncepten avser. Projektet genomförs i två etapper, varav den första omfattar utvecklingen av ovan nämnda designkoncept och den andra avser utvärderingen av desamma. Föreliggande rapport avser den första etappen, medan den andra redovisas i samband med slutrapporteringen av projektet.

Elanvändningen i våra bostäder sker vanligtvis utan närmare eftertanke och reflektion. Återkopplingen avseende hushållens individuella elanvändning är i den meningen mycket betydelsefull. I dagsläget är dock den förbrukningsinformation som hushållen har tillgång till mycket begränsad, i synnerhet i flerbostadshus. Syftet med projektet Visualisering av elanvändning i flerbostadshus har varit att utveckla och utvärdera designkoncept för individuell återkoppling till hushåll som bor i lägenhet. Designkoncepten avser en portabel display, en webbaserad statistiktjänst samt grafisk förbrukningsinformation på elräkningen. Det övergripande målet med projektet har varit att bidra till en mer medveten och därmed effektivare elanvändning i flerbostadshus.Utvecklingen har omfattat displayens och statistiktjänstens funktioner och gränssnitt samt en ändamålsenlig formgivning av den grafiska återkopplingen på elräkningen.

Utvärderingen har omfattat de boendes användning och upplevelser av de produkter och tjänster som designkoncepten avser. Projektet har genomförts i två etapper, varav den första har omfattat utvecklingen av ovan nämnda designkoncept och den andra har avsett utvärderingen av desamma. Föreliggande rapport avser i första hand den andra etappen, medan resultaten av den första har redovisats i sin helhet i en tidigare delrapport; Elforsk rapport 08:18.

Den trådlösa displayen tillhandahåller framför allt funktioner med mer eller mindre direkt återkoppling, medan statistiktjänsten och i synnerhet den grafiska förbrukningsinformationen i första hand avser uppföljning av den individuella elanvändningen med längre tidsperspektiv. Både displayen och statistiktjänsten erbjuder även möjligheten att göra jämförelser mellan olika tidsperioder och med liknande hushåll. Traditionella stapeldiagram i kombination med förtydligande färgsymbolik har visat sig vara mycket funktionella och har följaktligen använts i flertalet av designkonceptens gränssnitt. Enkelhet och lättillgänglighet har visat sig vara de viktigaste framgångsfaktorerna i samband med återkoppling till elanvändare.

Den grafiska förbrukningsinformationen på elräkningen har framstått som viktigast i den bemärkelsen att den utgör den återkoppling som når i särklass flest elkonsumenter. Egenskaperna enkelhet och lättillgänglighet har därför en särskilt avgörande betydelse i det här sammanhanget. Ett förhållandevis avskalat designkoncept har således förordats för ändamålet grafisk förbrukningsinformation på fakturan. Tidsupplösningen motsvarar faktureringsperioderna och grafens staplar representerar med andra ord de faktiska och förväntade månadsförbrukningarna under innevarande år samt i jämförande syfte de faktiska månadsförbrukningarna under föregående år.

Utvecklingen och utvärderingen av en portabel display har omfattat två olika designkoncept: Interactive Institute’s Energy AWARE Clock och ”Ingenjörsdisplayen”. Namnen härstammar från gränssnittens olika utformningar av förbrukningsinformationen, som i jämförande syfte har varit abstrakt men intuitivt tillgänglig respektive konkret och reell. De användartester som har genomförts i hemmiljö tyder därvidlag på att användarna föredrar en kombination av de båda designkoncepten. För en optimal användning av den här produkten krävs en central placering i hemmet, vilket innebär att yttre egenskaper såsom en tilltalande design har visat sig ha stor betydelse för användarna.Den webbaserade statistiktjänsten, som kallas Energiinfo™, utgör den återkoppling som tillhandahåller flest alternativa tidsupplösningar.

Förbrukningsinformationen som tillhandahålls på månads- och årsbasis har emellertid visat sig vara bäst lämpade för kontroll och uppföljning av hushållets elanvändning, vilka utgör de vanligaste användningsområdena. Användarnas syften är dock för övrigt högst varierande och möjligheten att anpassa förbrukningsinformationen för deras individuella behov har därför visat sig vara mycket betydelsefull i det här sammanhanget.

Samtliga designkoncept som studien avser har visat sig vara mer eller mindre ändamålsenliga i den bemärkelsen att de i viss mån bidrar till en ökad medvetenhet om hushållets egen elförbrukning samt ett förändrat beteende i syfte att effektivisera densamma. Inget av designkoncepten har dock framstått som viktigare än det andra i det avseendet, utan den förbrukningsinformation som de olika återkopplingsalternativen tillhandahåller kompletterar snarare varandra. Vidare har inget av designkoncepten visat sig vara idealiskt för uppdelningsåterkoppling, vilket innebär information om hur mycket olika hushållsapparater bidrar till den totala elkonsumtionen och tenderar att vara den förbrukningsinformation som hushållen har störst behov av.

Increased demand response is essential in order to boost the effectiveness of the Swedish power market. The all-embracing installation of automatic meter reading systems enables power suppliers to introduce hourly settlements in the residential sector. The aim of the study has been to assess the impact of electricity retailers’ physical and financial risk in customer segments with different heating systems as well as to estimate the potential of the electricity contract ”Fixed price with the right to return” in terms of economic consequences and risk management. The results show that households whose main heating system consists of a geothermal heat pump constitute the largest physical price and volume risk of suppliers. The gain of introducing hourly settlements in the residential electricity market has furthermore proven to be manifold from both an economic and risk reducing point of view.

Improved means of controlling electricity consumption plays an important part in boosting energy efficiency in the Swedish power market. Developing policy instruments to that end requires more in-depth statistics on electricity use in the residential sector, among other things. The aim of the study has accordingly been to assess the extent of variance in annual electricity consumption in single-family homes as well as to estimate the impact of household features and building properties in this respect using independent samples t-tests and one-way as well as univariate independent samples analyses of variance. Statistically significant variances associated with geographic area, heating system, number of family members, family composition, year of construction, electric water heater and electric underfloor heating have been established. The overall result of the analyses is nevertheless that variance in residential electricity consumption cannot be fully explained by independent variables related to household and building characteristics alone. As for the methodological approach, the results further suggest that methods for statistical analysis of variance are of considerable value in indentifying key indicators for policy update and development.

Increased demand response is essential to fully exploit the Swedish power system, which in turn is an absolute prerequisite for meeting political goals related to energy efficiency and climate change. Demand response programs are, nonetheless, still exceptional in the residential sector of the Swedish electricity market, one contributory factor being lack of knowledge about the extent of the potential gains. In light of these circumstances, this empirical study set out with the intention of estimating the scope of households’ response to, and assessing customers’ perception of, a demand-based time-of-use electricity distribution tariff. The results show that households as a whole have a fairly high opinion of the demand-based tariff and act on its intrinsic price signals by decreasing peak demand in peak periods and shifting electricity use from peak to off-peak periods.

This article aims to support the targeted worldwide green transition process by introducing and thoroughly analyzing a low-temperature heating and high-temperature cooling, smart building system. This concept allows for greater use of renewable energy while utilizing less input energy than conventional heating and cooling techniques. The proposed system consists of a reversible water-to-water heat pump driven by low-temperature geothermal energy. A rule-based control strategy is developed to establish an intelligent connection with the regional energy grids for peak shaving and compensating for the building's energy costs over the year. The dynamic simulation is carried out for a multi-family building complex in Stockholm, Sweden, using TRNSYS. The most favorable operating condition is determined via an artificial neural network-assisted tri-objective optimizer based on the grey wolf algorithm in MATLAB. The comparison of the proposed smart model with the conventional system in Sweden results in 332%, 203%, and 190% primary energy reduction, cost saving, and carbon dioxide emission mitigation, respectively. As indicated by the parametric results, the conflicting fluctuation between desirable and unfavorable indicators highlights the importance of multi-objective optimization. The grey wolf optimizer obtains 12% higher efficiency, 1.2 MWh lower annual bought energy, 24 $/MWh lower unit cost, and 5.1 MWh more yearly sold energy than the design condition. The scattered distribution reveals that tank volume and subcooling degree are sensitive parameters. According to the transient results, the suggested smart system can independently satisfy the building's heating, cooling, and electricity demands for more than 81% of the year, thanks to the two-way connection with the electricity and heating networks via the rule-based controller. 

As part of the transition to a sustainable future, energy-efficient buildings are needed to secure users' comfort and lower the built environment's energy footprint and associated emissions. This article presents a novel, realistic and affordable solution to minimize the footprint of smart building energy systems and enable higher renewable energy use in the building sector. For this, an intelligent system is being developed using a rule-based automation approach that considers thermal comfort, energy prices, meteorological data, and primary energy use. In order to lower the installation cost and part of the environmental footprint, batteries are not used, and the heat pump's size is decreased via component integration. Also, different renewable resources are effectively hybridized using photovoltaic thermal panels and an innovative biomass heater to increase the share of renewable energy, enhance reliability, and shave peak load. In order to secure feasibility, the suggested framework is assessed from the techno-economic and environmental standpoints for 100 residential apartments in Stockholm, Sweden. Our results show that 70.8 MWh of renewable electricity is transferred to the local grid, and the remaining 111.5 MWh is used to supply the building's needs and power the electrically-driven components. The biomass heater meets more than 65% of the space heating demand, mainly at low solar power and high electricity prices, illustrating the value of integration strategies to reduce the system's dependability on the local grid. The results further reveal that most energy purchases during the cloudy days and nights are repaid through the sale of excess renewable production during the warmer hours, with a bidirectional connection with the grid. The monthly energy cost is less than 140 $/MWh for most of the years. The cost can be held low due to the exclusion of batteries and minimizing the heat pump size. The proposed system has a low emission index of 11.9 kgCO2/MWh and can reduce carbon dioxide emissions by 70 TCO2/year compared to using the supply from the Swedish energy mix. 

Thermal energy storage (TES) is recognized as a well-established technology added to the smart energy systems to support the immediate increase in energy demand, flatten the rapid supply-side changes, and reduce energy costs through an efficient and sustainable integration. On the utilization side, low-temperature heating (LTH) and high-temperature cooling (HTC) systems have grown popular because of their excellent performance in terms of energy efficiency, cost-effectiveness, and ease of integration with renewable resources. This article presents the current state-of-the-art regarding the smart design of TES integrated with LTH and HTC systems. TES is first explained in basic concepts, classification, and design possibilities. Secondly, the literature on well-known existing control approaches, strategies, and optimization methods applied to thermal energy storage is reviewed. Thirdly, the specifications, types, benefits, and drawbacks of the LTH and HTC systems from the viewpoints of supply and demand sides are discussed. Fourthly, the smart design of TES integrated with the LTH and HTC systems based on the control approach/strategy, optimization method, building type, and energy supplier is investigated to find the newest technology, ideas, and features and detect the existing gaps. The present article will provide a realistically feasible solution for having a smart storage configuration with the maximum possible energy efficiency, reliability, and cost-effectiveness for the building owners and the energy suppliers.

This work presents an innovative, practical, and cost-effective solution for advancing state-of-the-art intelligent building energy systems and aiding the intended worldwide green transition with maximum renewable integration. The vanadium chloride cycle, electrolyzer unit, and Alkaline fuel cell are powered by the sun's and wind's energy to produce/store/use hydrogen. A rule-based control scheme is designed to provide a sophisticated interplay between the demand/supply sides, components, and local energy networks to reduce peak capacity, lower emissions, and save energy costs. TRNSYS is used to analyze and compare the techno-economic-environmental indicators of the conventional system and the suggested smart model for a multi-family building in Sweden. A grey wolf method is built in MATLAB with the help of machine learning to determine the optimum operating state with the maximum accuracy and the least amount of computational time. The results reveal that the suggested smart model considerably saves energy and money compared to the conventional system in Sweden while lowering CO2 emissions. According to the optimization results, the grey wolf optimizer and machine learning techniques enable greater total efficiency of 13 %, higher CO2 mitigation of 8 %, a larger cost saving of 38 %, and a reduced levelized energy cost of 41 $/MWh. The scatter distribution of important design parameters shows that altering the fuel cell current and electrode area considerably impacts the system's performance from all angles. The bidirectional connection of the proposed smart system with the heating and electrical networks through the rule-based controller demonstrates that it can supply the building's energy requirements for more than 300 days of the year. Eventually, the major contribution of the vanadium chloride cycle in the summer and the electrolyzer in the winter to the creation of hydrogen highlights the significance of renewable hybridization in reducing the dependence of buildings on energy networks.

This article proposes a cutting-edge smart building design that contributes to sustainable development objectives by fostering clean energy, facilitating sustainable cities and communities, and promoting responsible consumption and production. The main goal is to create a clever rule-based framework that will boost the penetration of renewable energy in local grids, reduce the size of the components and, consequently, investment costs, and promote the shift towards a more environmentally friendly future. The system is driven by photovoltaic thermal panels, a novel biomass heater scheme, and a scaled-down heat pump to supply the entire energy demands of multi-family houses. The grey wolf optimizer and a cascade forward neural network model achieve the most optimal condition. According to the results, the suggested smart model outperforms the conventional Swedish system, with an energy cost of 121.2 euro/MWh and a low emission index of 11.2 kg/MWh. The results show that knowing how biomass price changes affect the heat pump's operational mode is crucial to ensuring the system's economic viability. In comparison to the design condition, the optimized model increased efficiency by 3.8% while decreasing overall cost (2.1 euro/h), emission index (4.4 kg/MWh), and energy costs (29.9 $/MWh). The results further demonstrate that the heat pump meets the vast majority of the year's heating needs, but as electricity prices rise in December, the biomass heater becomes the principal energy provider. May is the month with the lowest average monthly cost, while December and July stand out as the most expensive months of the year due to a dramatic increase in demand. Eventually, the results show that the system runs without external energy sources through the designed optimal control framework and generates excess electricity for around half the year.

Mälarenergi’s vision is a world where we live and operate together without climate impact. This degree project has examined which opportunities Mälarenergi Elnät has in order to work towards this vision by looking more closely at whether their bigger substations can become self-sufficient in terms of heating, cooling and battery charging. The purpose of this degree project was to investigate how heat recovery from the substations’ transformers and the installation of PV-systems could contribute to both more environmentally friendly and self-sufficient substations. In addition to that, the economics and how this would affect the Swedish power grid regulation were of interest. The thesis was based on current values and data for oil temperatures and installed power in three of Mälarenergi Elnät’s substations. In addition to this, the thesis also includes a literature study, where previous research in heat transfer from power transformers, up-to-date information about PV-installations and the power grid regulation in Sweden were studied. The results of the thesis showed that both PV-installations and heat exchange for heating the station buildings could be of great benefit for Mälarenergi Elnät. In all but one case, the energy saving measures resulted in lower life cycle costs than if no measures were taken. It shows that the measures investigated in the thesis are not only good from an environmental perspective, but also has economic profitability. 

District heat is currently more exposed for competition than it has been for several years. Since the mid-1980s, district heat has dominated the heat market, but is now in a tougher competitive situation due to the increasing popularity of heat pumps. This, in combination with energy efficiency, has led to a stagnation of delivered energy. The purpose of the study is to investigate the district heating's current competitive situation in Västerås. This will be investigated based on pricing, performance and paragraphs. In order to get a comprehensive picture of the heat market and to find out what factors customers prioritize, housing companies, house makers and villa owners were interviewed.

The study's results show that house owners prioritize delivery reliability, followed by economy and environment in the choice of heating method. Actors' views on pricing were different depending on the preferred heating method, where the different views were primarily about the operating and maintenance costs of heat pumps. In order to analyze pricing the life cycle cost was calculated on the basis of real cases. This was done by creating a calculation model in Excel. The result of pricing shows that district heating was the best option for all cases. However, from a new construction perspective, geothermal heat pump for small houses had similar life cycle cost as district heating, while district heating was superior in price for the larger houses. All cases when a customer had change from district heat to heat pumps were unprofitable due to the switching cost that arises.

Performance was evaluated by the environmental impact and delivery reliability of the methods. The consequential life cycle assessment was used when calculating environmental impact. The result showed that the district heating in Västerås has a positive environmental impact because of the social benefits it provides. Heat pumps had a negative impact on the environment in all cases. The delivery reliability was studied through actors' views in combination with scientific research, which resulted in the view that district heating is better.

The evaluation of paragraph was limited to Boverket’s building regulations. The competitive situation is currently skewed, where heat pumps have a big advantage as houses can limit their energy efficiency with heat pumps.

The future of district heating in Västerås is bright. The challenge is to keep their market domination by maintaining a competitive price as the heat market is facing changes with reduced heat demand and tougher competition.

There is a rising demand for energy and at the same time, fossil fuels need to be phased out

due to global warming. This means that the energy needs to come from renewable energy

resources, for instance photovoltaics. One issue with such energy sources is that they may

have variating production which can induce issues with stability in the electrical grid.

This study aims to investigate hydrogen in Sweden as energy storage and vehicle fuel.

Methods used are literature review, interviews and calculations.

According to the interviews are one of the main issues with implementing hydrogen the lack

of standards. Today it is the local fire department who approves of hydrogen system which

induces irregularities in the handling. It is also said that none of the projects in the interviews

is profitable moneywise, something that also can be seen in the calculations. In order to reach

break-even some serious changes with regarding costs of components or the alternative, for

instance, fossil fuel and electricity. The application closest to break even is transportation

which demands a 90 % decrease in component price or a 10-fold increase in fossil fuel price.

In conclusion, there are future applications for hydrogen as energy storage, vehicle fuel and

in industry, apart from the current industry applications. The most sustainable way to

produce hydrogen is via electrolysis with emission-free electricity. In order for hydrogen to

become economically viable, the target case is not enough but even greater cost reductions

are needed.

Gas-driven sorption heat pumps (GDSHPs) exhibit great possibilities in the reduction of energy use and environmental impact of heating systems that utilise natural gas. By utilising renewable thermal energy from the environment, that is, air, ground or water sources, significant reduction of primary energy use can be achieved. However, high cost, low coefficient of performance (COP) and large volume per unit thermal power produced have limited the proliferation of GDSHPs. In this work, exploiting the benefits of reversible chemical reactions in sorption systems, with no internal moving parts, noise, vibration, and a maintenance-free reactor design, two novel modular prototype sorption components were developed and evaluated experimentally. They were designed to operate as part of an intermittent cycle GDSHP to deliver heat directly to a load or to a stratified hot water store. Prototype 1 was an ammonia-salt basic sorption unit while prototype 2 was an ammonia-salt resorption unit both employing proprietary composite sorbent materials. Test results showed that the prototype 2 reactor produced a specific heating capacity of 46 W/litre at a temperature lift of 50°C yielding a COP of 1.38. Prototype 1 demonstrated higher heating capacity of 73 W/litre at a temperature lift of 70°C but exhibited lower COP of 1.10. Given its higher COP but lower temperature lift, prototype 2 could be employed in a GDSHP designed for moderate heating demands or where a ground source heat exchanger is employed as the low temperature heat source. In the case where a higher temperature lift is required, for example, for an air-source GDSHP unit then the prototype 1 design would be more applicable.

This paper develops, implements, and applies a mathematical model for economic unit dispatch for a novel cogeneration concept (CHP-HP-FG-CS (CHP with compression heat pump and cold storage using flue gas heat)) that increases the plant's operational flexibility. The CHP-HP-FG-CS concept is a high-efficiency and widely applicable option in distributed cogeneration better supporting the co-existence between cogenerators and intermittent renewables in the energy system. The concept involves integrating an efficient high-temperature compression heat pump that uses only waste heat recovered from flue gases as low-temperature heat source, and an intermediate cold thermal storage allowing for non-concurrent operation of the cogeneration unit and the heat pump unit. The model is applied for a paradigmatic case study that shows how the integration of a heat pump affects the operational strategy of a cogeneration plant. It is found that CHP-HP-FG-CS offers significant reductions in fuel consumption (-8.9%) and operational production costs (-11.4%). The plant's fuel-to-energy efficiency increases from 88.9 to 95.5%, which is state-of-the-art. The plant's intermittency-friendliness coefficient Rc improves only marginally due to the constrained nature of the low-temperature heat source and the associated small capacity of the heat pump unit. Significant improvements in Rc are found when increasing the heat pump capacity assuming the availability of an unconstrained heat source

The Saharan regions of Algeria, which represent almost 90% of the total area of the country, have severe energy problems due to insufficient or lack of energy access. The sustainable development of those areas must aim at securing and increasing primary production, especially in the agricultural and pastoral sectors. The production itself depends on the supply of water available at great depths. However, the potential volumes of water pumped by photovoltaic water pumping systems are generally greater than the annual requirements for crop irrigation. In this study, we optimized the photovoltaic array, the storage tank and efficient use of the water produced by the pumping system for the irrigation of one hectare palm grove. This excess water produced was reduced by a judicious association by planting other crops (tomato, wheat and sweet pepper). The utilization rate has been improved from 56% to 86%, on the one hand. On the other hand, the impact of the yield and the prices on the economic viability was studied. The project is economically viable for a price per kg of date of 500.00 DA and a yield varying from 20 to 50 kg/tree, and the payback period varies from 3.34 to 1.22 years. The project is not economically viable for a price per kg of date of 100.00 DA/kg for a yield less than or equal to 30 kg/tree. A sensitivity analysis has shown that the photovoltaic water pumping system becomes more competitive than conventional diesel water pumping systems for diesel price beyond 53.98 DA/l (0.38 €). The results are very encouraging for the wide use of photovoltaic water pumping systems for multiple-crop irrigation in the Saharan regions. 

The global community is facing great challenges as the energy system is transforming towards more reliable, effective, clean and renewable production. Small-scale and micro networks will play an important role in this changeover. Its advantages over today’s large conventional energy systems are their reliability and stability. In small-scale and micro networks, there is usually a variety of production units such as photovoltaic, wind power and micro-combined heat and power (micro-CHP). In this study, a small-scale network with an application of two different types of biogas fueled micro-CHPs is analyzed. The units are a micro gas engine (MGM) and a micro gas turbine (MGT). The application of micro-CHP is validated using a reference facility connected to a small-scale district heating network. The reference facility is a heat production plant at a horse race track outside Eskilstuna, Sweden consisting of an oil boiler, a pellet boiler and a heat storage tank. The potential in replacing the oil boiler with renewable micro-CHP is investigated. A simulation model is built in the software GAMS, using Mixed Integer Linear Programming (MILP) and the solver CPLEX, and the model is simulated using the heat demand from the horse race track. Results from the model validation shows that it is possible for both the MGM or the MGT together with the pellet boiler and the heat storage tank to fulfill the heat demand of the facility. The horse race track handles 4 000 m3 of horse manure annually, which is transported 124 km to a compost treatment facility. Therefore, a general analysis of biogas production from horse manure is conducted in order to investigate the possibilities for better horse manure treatment on site. A calculation for a biogas reactor with a capacity for the maximum biogas requirement of the micro-CHP is implemented. Horse manure is suggested to be co-digested with food waste, in order to provide a higher biogas exchange. The result of a Life Cycle Cost (LCC) analysis indicates difficulties in justifying an investment of a micro-CHP together with a biogas plant at current prices for heat and electricity. The results show that the payback period for the MGM is 7 years which is 2 years shorter than its lifetime and the MGT payback period is 12 year which also is it lifetime. The MGM shows the largest investment potential since it has an investment cost approximately 860 kSEK lower than for the MGT. The MGM also has a slightly higher electrical efficiency which results in higher revenues from produced electricity. The chosen MGM in this study is slightly smaller than the MGT, resulting in a lower biogas demand and a lower investment cost for a biogas plant. A sensitivity analysis shows great impact of the electricity price on the payback period for both types of micro-CHP. The results show that with an electricity price of 280 SEK/MWh, both the MGM and the MGT repays within their lifetime. But since MGM has a higher net present value at all electric prices, is the MGM considered to be a more economical feasible investment.

What the authors think should be highlighted is also the environmental benefits of more efficient treatment of horse manure at the horse race track together with the possibility of local production of fuel resulting in reduced CO2 emissions by 47 tons/year.

The construction sector is responsible for 20% of Greenhouse Gas (GHG) emissions, of whichdiesel-powered construction equipment are large contributors. Currently there are many ongoing Fuel Cell (FC) powered construction equipment projects as it is seen as an attractiveoption to power the futures zero-emission heavy-duty machines. Although an attractivealternative, hydrogen FC has drawbacks such as releasing liquid water and water vapor viathe exhaust as a byproduct which in their working environment can cause a suite of issues. Agap in the literature on the water exhausted is present and therefore this degree project seeksto investigate the amount, and ratio, of liquid water and water vapor released from threetypical construction equipment drive cycles which would allow further investigation onappropriate management. The method used for this degree project was to modify a pre-mademodel in Simulink built with Simscape blocks. The model was modified to represent a FCsystem used in a test-rig by implementing experimental and measured data for design andoperating parameters. Different pressures, temperatures, and cathode inlet RelativeHumidity (RH) were investigated to find their effect on the performance and water in theexhaust. A sensitivity analysis of different unknown parameters was also conducted tounderstand their influence on the results. For the reference case, the results showed that foran articulated hauler, the water in the exhaust was 26% liquid which translates to 8.6 kg for a1-hour drive cycle. The crawler excavator and wheel loader, both had 30-minute drive cyclesand had 1.1 kg liquid water with a liquid water ratio of 7% and 0.7 kg liquid water with aliquid water ratio of 5% in the exhaust respectively. For a full 8-hour workday with twoparallel FCs connected, the articulated hauler liquid water amount is 137.6 kg, the crawlerexcavator 35.2 kg, and the wheel loader 22.4 kg. Overall, it was found the liquid water ratiocould be changed to a large extent with different operating parameters, where thetemperature had the greatest influence. The system and stack efficiencies did not changeconsiderably with different operating parameters, meaning that the total water in the exhaustremained similar for the different respective drive cycles. 

This thesis investigates how combined heat and power plants (CHP) produce electricity, with respect to several external factors including outdoor temperature and electricity prices. The purpose is to develop and evaluate a tool, with the aim to increase the understanding of CHP plants electricity production behaviour. This tool resulted in an optimisation model, developed in Python and using the CVXPY package. The objective of the model is to include a system of production units and optimise the production from these by minimising the production costs, while also considering technical constraints. Inspiration for the model was found from a literature review and from interviews with people working in the CHP sector, where the latter also provided historical production data used for validation. When comparing the modelled yearly electricity production with the historical data for the same year, it was found that the model deviated less than 10 percent for the two real district heating systems where the model was implemented. In conclusion, it is seen that the model behaves similar to the actual plants when looking at the electricity production; however, the behaviour of the model is slightly exaggerated with faster changes in the electricity production. Though, the results show that the developed model can be used to enhance the understanding of how CHP plants produce electricity. 

Grassland degradation is considered as one of the worst environmental and economic problems in China because of the negative impacts on water and food security. The application of the photovoltaic water pumping (PVWP) technology for irrigation is an innovative and sustainable solution to curb the progress of grassland desertification and to promote the conservation of farmland in remote areas. The combination of PVWP with water saving irrigation techniques and the sustainable management of the water resources enhances the grass productivity enabling to halt wind and rainfall erosion and to provide higher incomes and better living conditions for farmers. PVWP systems have been used for more than 40 years especially for drinking purposes, livestock watering and irrigation in small-medium size applications. Nevertheless, several knowledge gaps still exist and system failures still occur, which are mainly bounded to the system design procedure and optimization. The technical and economic feasibilities related to the system implementation, especially effectiveness and profitability, need to be addressed. Moreover, irrigation in remote areas constrained by availability of water resources has to be investigated for a better understanding of PVWP system integration with the environment and for optimization purposes. This thesis is to bridge the current knowledge gaps, optimize system implementation and prevent system failures 

Validation of the models adopted and optimization of the system on the basis of solar energy resources and exploitable groundwater has been performed for a pilot PVWP system in Inner Mongolia. The match between the water supplied through the pumping system and the grass water demand has been studied, and the effects of pumping on the available resources and the crop productivity have been evaluated. The economic analyses have also been conducted in order to establish the most cost effective solution to provide water for irrigation and to evaluate the project profitability. In addition, the CO₂ emission reductions by using PV technology have been assessed as well.

It was found that the proper designed PVWP system represents the best technical and economic solution to provide water for irrigation in the remote areas compared to other water pumping technologies, such as diesel water pumping and wind power water pumping due to the high positive net present values and short payback periods.

This study aims to develop a gridded optimization model for studying photovoltaic applications in Nordic countries. The model uses the spatial and temporal data generated by the mesoscale models STRÅNG and MESAN developed by the Swedish Meteorological and Hydrological Institute. The model is developed based on the comparison between five irradiance databases, three decomposition models, two transposition models, and two photovoltaic models. Several techno-economic and environmental aspects of photovoltaic systems and photovoltaic systems integrated with batteries are investigated from a spatial perspective. CM SAF SARAH-2, Engerer2, and Perez1990 have shown the best performances among the irradiance databases, and decomposition and transposition models, respectively. STRÅNG resulted in the second-best irradiance database to be used in Sweden for photovoltaic applications when comparing hourly global horizontal irradiance with weather station data. The developed model can be employed for carrying out further detailed gridded techno-economic assessments of photovoltaic applications and energy systems in general in Nordic countries. The model structure is generic and can be applied to every gridded climatological database worldwide.

The water-food-energy nexus approach was identified by the 2008 World Economic Forum as a key concept and methodology for studying and optimizing the important links among energy, water, and food. Energy, water, and food are basic human needs and are threatened by megatrends such as climate change and population growth. Renewable energies play an important role in the energy-water nexus because their water footprint, except for hydropower and bioenergy, is extremely low as compared to conventional fossil-based energy systems, especially for solar power and wind power conversion systems. Solar power and wind power systems reduce pressure on water resources by allowing for better water management, especially when it comes to conflicts between water for energy versus water for food. Renewable energies also represent a key pathway for combating climate change. This chapter introduces the concept of the water-food-energy nexus and its complex interrelationships and gives particular attention to renewable energies. Subsequently, several water-food-energy nexus aspects related to applications of renewable energies are investigated more deeply, with reference to practical examples. Particular attention will be given to floating photovoltaic systems, photovoltaic water-pumping systems, and agrivoltaics. The chapter concludes with the competition of land for energy versus land for food and on the role of the nexus in renewable-based wastewater systems.

Irrigation through photovoltaic water pumping (PVWP) system represents one of sustainable and attractivesolutions regarding the problems related to the Chinese grassland desertification. This paper is to investigatethe economics of PVWP systems taking in consideration of the key parameters affecting the sizing, and furtherthe initial capital cost (ICC), the life cycle cost (LCC) and revenues. In particular photovoltaic (PV) modules cost,availability of the well and of the irrigation system, designing water-head, irrigated area and related waterdemand, fuel price and grass production are investigated for the sensitivity analysis. The possibility ofcombining water pumping with electricity production for maximizing benefits is also discussed. Both PVWP anddiesel water pumping (DWP) systems are compared in terms of ICC and LCC. LCC, sensitivity, break-even point(BEP), net present value (NPV) and payback period (PBP) analyses are used to compare and evaluate theeconomic feasibility of the different alternatives investigated. The results show that the availability of the welland the depth of the ground water resources are the most sensitive parameters affecting the initial capitalcosts whereas the grass production and incentives affect mainly the NPV and PBP. The co-benefits for carbonmitigation and carbon credit trading through implementing photovoltaic water pumping system for the Chinesegrassland are also addressed in this paper.

Agriculture is one of the most water- and energy-intensive sectors of the economy, consuming about 70% of global freshwater withdrawals. Access to clean and affordable water for irrigation is an essential step towards guaranteeing water and food security, improving incomes and living standards, decarbonizing an energy-intensive sector and attaining the United Nations Sustainable Development Goals (SDGs), in particular SDGs 2 (Zero Hunger), 6 (Clean Water and Sanitation), 7 (Affordable and Clean Energy), and 13 (Climate Action). Ensuring access to water for irrigation, as well as for other agricultural (i.e., livestock watering), domestic, and industrial purposes is a global challenge, and it is more challenging in remote areas where the grid connection is often not available. Solar-powered pumping systems represent a renewable solution for the decarbonization of the irrigation sector worldwide. While solar water pumping systems were used in the past to supply water for irrigation, livestock, and domestic purposes only in remote locations without access to the electric grid, the drastic drop in photovoltaic (PV) modules prices has made the technology also competitive for on-grid applications. This chapter reviews the configurations of solar water pumping systems for irrigation, highlighting the water–food–energy nexus aspects and recent advances, reviewing case studies, and analyzing the economics and current and future challenges. 

Photovoltaic (PV) systems in Sweden have primarily been seen as an energy efficiency measure to reduce the amount of purchased electricity for buildings, both residential and commercial. Only recently utility-scale solar systems have begun to increase their share of the solar market to support national energy and emissions targets. Due to the economies of scale, conventional ground-mounted PV (CGMPV) installations represent the best solution for producing electricity at the lowest specific initial investment costs. This relatively new solar market segment, with large-scale ground-mounted solar farms on agricultural land, has faced several challenges with the permitting process. Agricultural land that is suitable for cultivation is of "national importance" according to the Swedish Environmental Code. Cultivable agricultural land may be exploited for other purposes on a permanent basis only if it is necessary to satisfy essential societal interests and there is no other possible land to use within the area in question. Traditionally, ground-mounted solar farms have increased competition for land resources for food production and drawn criticism in the so-called "food-versus-fuel (electricity)" debate over whether agricultural land should be used for electricity generation or food production. Agrivoltaic (APV) systems represent an intelligent solution to avoid land use competition by combining arable farming and electricity production on the same agricultural land. The main objective of this project was to study how APV systems perform from an energy, agricultural and economic perspective compared to CGMPV systems and agriculture production. The project aimed to highlight advantages and disadvantages of APV systems at northern latitudes with an energy-food-water perspective. The aim was pursued by establishing an APV test site, the first APV system in Sweden, monitoring its performance both from an energy and agricultural point of view, and developing new techno-economic models. Data from the APV test site were used to better understand how APV systems at northern latitudes affect: 1) the efficiency of the solar modules; 2) crop productivity, and 3) the financial return for ground-based solar PV systems. The first agrivoltaic system in Sweden has been built on a permanent ley grass field, at Kärrbo Prästgård, Västerås, and research activities have been carried out on the ley grass during 2021 and 2022. As in previous research studies in other countries, we defined three sub-fields: 1) a sub-field is covered only by the ley grass (reference area), 2) a sub-field is a CGMPV system 11.8 kWp solar PV system with two rows of solar modules with a 30° tilt and 3) the last subfield is a  22.8 kWp APV system with three rows of vertically mounted solar modules, with ley grass between the modules. This field set-up allowed for comparisons between practices (agriculture and electricity generation) and technologies (CGMPV systems versus APV systems). The calculated specific electricity production during a typical meteorological year for the APV system and the CGMPV system was 1,067 kWh/kWp/year and 1,116 kWh/kWp/year, respectively. Nevertheless, the APV system tends to have higher efficiency than the CGMPV systems due to the solar irradiation patterns on the solar cell surfaces and wind cooling of the PV modules. The main results of the project in terms of shadow effects on the ley grass showed that the APV system did not significantly affect the productivity of the forage grass in 2021-2022. There was no statistically significant difference between the yield of the samples taken in the APV system and the reference area. Even so, the yield per hectare is reduced by approximatively 10%, when the distance between the vertically mounted solar modules is 10 meters, due to the area under the solar modules that cannot be mechanically harvested. The measurements performed at the test site allowed us to validate the earlier developed model for both electricity production and the effects of shading on crop production. Having a model to assess crop yields under APV systems is of utmost importance to be able to pre-assess the system's effects on food production, which is one of the main goals of APV system regulations worldwide. From an economic perspective, APV systems cannot compete with CGMPV systems due to lower electricity production per hectare, lower density of the solar modules per hectare, and higher investment costs per hectare. Nevertheless, APV systems can be the solution to overcome the legal obstacles that prohibit or hinder the use of agricultural land for electricity generation with PV systems. 

Typically, PV water pumping (PVWP) systems for irrigation are normally designed based on the worst conditions, such as high water demand and low solar irradiation. Therefore, the installed PVWP systems become oversized in most of time. Since the conventional control systems don't optimize the water supply, the water losses are increased. To remedy the problems related to the operation of the oversized systems, a novel control system is proposed. The control unit interacts between water demand and water supply in order to pump only the amount required by crops. Moreover, the novel control system substitutes the conventional protection approach with a method based on the ground water resources availability and response. The novel control system represents an innovative solution for water savings in PV watering applications.

Distributed generation, and active distribution networks constitute an economic and technically viable alternative for reducing green house gases emissions and increase the use of renewable energy sources in local distribution grids. These active networks allow replacing large generators, usually located far from the consumption loads, thus considerably minimizing distribution losses and increase renewable energy penetration. However, designing and successfully controlling these complex networks, becomes a great engineering challenge; most computational modeling and simulation tools available for these systems are either focused on the individual generation components themselves, or the economic dispatch of multiple generators. Moreover, these tools often rely on closed source commercial software that use manufacturers' data for predefining the parameters of the models' components. This approach does not provide enough flexibility to users, since often is not possible to adjust these parameters. This paper presents object- oriented, component-based, open software components for simulating and optimizing the operation of active distribution networks, including multiple distributed generators and energy using the Modelica open-source modeling language. 

The smart metering infrastructure in Sweden allows electricity providers to offer electricity RTP (real time pricing) to homeowners, together with other dynamic pricing contracts across the country. These contracts are supposed to encourage users to shift power consumption during peak hours to help balance the load in the power system. Of all the available contracts in Sweden, monthly-average price holds the largest share, in response to the low electricity prices during the last three years. It is not clear if RTP will become a popular dynamic pricing scheme since daily price fluctuations might keep customers away from this type of contract. Literature review suggests that RTP adoption is only beneficial when combined with the use of customer demand flexibility, but it does not provide enough information about users adopting RTP without changing their electricity usage profile. This paper studies the economic impact if customers would shift to RTP contracts without adopting demand-side management. To achieve this, electricity costs from a large group of households were calculated and compared between both pricing schemes using the hourly consumption data of a 7-year period. Results suggest that the RTP electricity contract offer a considerable economic savings potential even without enabling consumer demand-side management. 

The introduction of a deregulated power system market and development of smart-metering technologies in Sweden, bring new opportunities for fully exploiting its power system efficiency and reliability, such as price-based demand response (DR) programs at a large scale for household, commercial and industrial users. 

The deployments of these DR programs require, however, very accurate demand forecasting models. The traditional approach of obtaining the total energy use and peak demand does not offer the required detailed information. This article reviews several methodologies for forecasting electricity consumption from a bottom-up perspective in order to define the required parameters and structure for obtaining an energy model. This model will finally include energy usage data, behavioural parameters obtained from a survey conducted with 5 000 end-users in different Swedish distribution system operators’ areas, and physical conditions for the facilities (internal/external temperatures and insulation materials). This information is provided from previous research studies performed at Mälardalen University and Swedish electric utilities companies. 

The obtained model should be able to adjust its parameters dynamically in order to simulate several demand-response scenarios based on four different strategies: time of use pricing, use of curtailable/interruptible rates, imposition of penalties for usage beyond predetermined levels, and real time pricing.

The use of ground-sourced heat pumps as main heating systems has increased in Sweden in the last fifteen years to the point that it is the country with the highest amount of GSHP in Europe. Heat pumps are chosen by many households due to their economic savings value; In contrast, electricity prices in Sweden have almost doubled since 2006, threatening their economic benefits. It is therefore, essential to understand GSHPs impact on the user´s electricity consumption and provide suitable demand-response programs that could help develop a model capable of forecasting consumption and provide decision support information to make the best use of the technology. This paper analyses questionnaire surveys and consumption patterns were evaluated for 322 households with installed GSHPs and different pricing schemes in order to increase the understanding of mass use of this type of heating system.

The wind power industry is one of the fastest-growing renewable energy industries in the world. Since more energy can be extracted from wind when the density is higher, a lot of the investments made in the wind power industry are made in cold climates. But with cold climates come harsh weather conditions such as icing. The icing on wind power rotor blades causes the aerodynamic properties of the blade to shift and with further ice accretion, the wind power plant can come to a standstill causing a loss of power, until the ice is melted. How big these losses are, depend greatly on site-specific variables such as elevation, temperature, and precipitation. The literature claims these ice-related losses can correspond to 10-35% of the annual expected energy output. Some studies have been made to standardize an ice loss determining method to be used by the industry, yet a standardization of calculating these losses do not exist. It was therefore interesting for this thesis to investigate the different methods that are being used. By using historical Supervisory Control and Data Acquisition (SCADA) data for two different sites located in Sweden, a robust ice determining code was created to identify ice losses. Nearly 32 million data points are being analyzed, and the data itself is provided by Siemens Gamesa which is one of the biggest companies within the wind power industry. A sensitivity analysis was made, and it was shown that a reference dataset reaching from May to September for four years could be used to clearly identify ice losses. To find the ice losses, three different scenarios were tested. The three scenarios use different temperature intervals to find ice losses. For scenario 1 all data points below 0 degrees are investigated. And for scenario 2 and 3 this interval is stretching from 3 degrees and below versus 5 degrees and below. It was found that Scenario 3, was the optimal way to identify the ice losses. Scenario 3 filtered the raw data so that only data points with a temperature below five degrees was used. For the two sites investigated, the annual ice losses were found to lower the annual energy output by 5-10%. Further, the correlation between temperature, precipitation, and ice losses was investigated. It was found that low temperature and high precipitation is strongly correlated to ice losses.

Globally there is a rise in use of renewable sources of energy particularly solar energy and agrivoltaic systems emerges as a system which helps to increase the land use efficiency. In previous research agrivoltaic systems are evaluated based on some key performance indicators like energy yield, land equivalent ratio, agricultural yield etc. This research project aims to evaluate the performance of agrivoltaic system in terms of water food energy nexus. Further in this study the performance of Sweden’s first agrivoltaic system set up outside Västerås is evaluated by varying the gap between the rows of photovoltaic modules. In this agrivoltaic system vertical bifacial photovoltaic modules are used and the PVsyst® is used for designing and simulating the photovoltaic system. For this different indicator has been used which evaluates the performance in terms of water food energy nexus. Then the performance of Swedish agrivoltaic system is compared with German agrivoltaic system. Results shows that in Swedish agrivoltaic system row spacing of 10 m achieved highest score in terms of water food energy nexus indicators. Swedish system has ground coverage ratio of 20.76 %, the annual energy yield is found to be 622 MWh/ha and land equivalent ratio is calculated to be 1.10. The economic analysis of system shows the net present value of 31176 SEK and levelized cost of electricity to be 1.11 SEK/kWh. Profitability of this system increased when most of the generated electricity is self-consumed. German agrivoltaic system achieve higher score on water food energy nexus indicator scale.

Multi-core architectures have grown to be a popular choice for deploying Mixed Criticality Systems (MCS). The focus of research in MCS has been to provide timing assurances for jobs with different criticality levels. Due to their significant processing demands and energy-aware/constrained nature, energy conservation in these systems is becoming mandatory. This article presents, mcDVFS, an energy management technique based on Dynamic-Voltage-and-Frequency-Scaling for multi-core MCS. mcDVFS achieves significant energy reduction while maintaining timing guarantees. It also prioritizes quality of service whenever feasible. Extensive experimental simulations show energy savings of ≈ 52% and 34% when compared to EDF-VD and EDF-VD with QoS. 

By utilizing biomass gasification, the energy contentof the biomass can be utilized to produce gas to be used forcogeneration of heat and power as well as other energy carrierssuch as fuels for vehicles. The concept is suitable forapplication to existing CHP plants as well as for utilizing spentliqour in small scale pulp and paper mills. The introductionwould enable flexible energy utilization, use of problematicfuels as well as protects the environment by e.g. avoiding therelease of toxic substances. In this paper, the possibilities todevelop this concept is discussed. In this paper we comparedifferent gasification processes with respect to what gas qualitywe get, and how the gasification can be modelled usingdifferent modelling approaches, and how these can becombined. Results from simulations are compared toexperimental results from pilot plant operations in differentscales and with different processes like CFB and BFBTechnologies, athmospheric and pressurized, and using steam,air and oxygen as oxidizing media.

This paper presents a study on alternative pathways to a fossil-fuel free regional energy system in the Mälardalen region of Sweden with a population of 3 million inhabitants. We describe and address how the region can be made independent of fossil fuels by integration of resource management, technology advances, and behavior change in energy use. First we investigate the consumption pattern of the inhabitants. Then we study what resources are available, and how these can be used to fulfill the different demands. If we just use the resources in a pattern of business as usual today without changing the behavior, the balance between demands and resources is difficult to reach. By combining a slightly different behavior and a change of crops it could be possible to fulfill the needs. Some advanced technological solutions have also been proposed. For example, dedicated biomass energy plants such as fodder sugar beats can be used for ethanol production. Also Salix, straw, hemp and some cereals can be used and the residues can be gasified to produce dimethylether (DME), which is good as a replacement for diesel fuel. Still the fuel demand for transport is high, and the vehicle weight could be further reduced. For example, by going back to the car size we had only ten years ago the weight would be 25-30 % less, and fuel consumption would be at least 15 % lower. With diesel engines instead of Otto-engines the fuel consumption could be reduced by 35 %, and with hybrid technology additional 20% fuel reduction could be gained. Improved public transportation will also give a positive effect especially for those commuting between the larger cities and between the cities and the suburbs. The results of our calculations show that it would be possible to accomplish a fossil-free energy system in the Mälardalen region. The results of this study are important since it shows that an energy balance without fossil fuels could be possible for an area with a population in the order of 3 million people, which would also be valuable in studies of other areas in the world.

There is a potential to utilize a significant amount of renewable energy in Sweden and European union(EU). Biomass can fulfil some 8500e12,500 TW h/y in EU, while the total utilization was 16,084 TW h/y2009. Even though there is a significant amount of wind power, hydro power and potentially also solarpower, it still is most economical to reduce the consumption of heat, electricity and fuels for vehicles. Asaved kWh is normally cheaper than to produce one extra. In this paper different opportunities for savingenergy will be discussed. This includes manufacturing industries, process industries, power plants andenergy systems including distribution of power and smart grids, food production and transportation.There is also a major potential to save energy in buildings, both in the north where it is cold, and in thesouth where it can be very hot summer time. Here the potential is to avoid cooling instead. Technicalsolutions as well as economic incentives are covered. Environmental aspects are addressed, so that thesolutions will be long term sustainable.

A transcritical CO 2 heat pump (HP) system for residential space heating integrated with direct dedicated mechanical subcooling (DMS) is proposed, and mathematical models are developed to study the annual energetic and economic performances considering the influence of frosting. The operation characteristics by adopting different heating terminals used in five typical cities are also assessed. The results show a maximum coefficient of performance (COP) is achieved at the optimum discharge pressure and subcooling degree. The COP is promoted by 24.4% and the discharge pressure is decreased by 2.093 MPa at the ambient temperature of −10 °C and water supply/return temperature of 45/40 °C. The seasonal performance factor (SPF) is enhanced more noticeably for severe cold region. For the case of Harbin using floor-coil radiator (FCR) or normal fan-coil unit (N-FCU) as heating terminal, SPF is improved by 32.0%. The highest SPF is achieved when small temperature difference fan-coil unit (STD-FCU) is employed. The exergy efficiency can also be apparently improved, especially for the cities located in severe cold region and using FCR or N-FCU as heating terminal due to the reduction in throttling loss of CO 2 system. The purchased equipment cost and electricity cost of the CO 2 HP with DMS are both lower than those of traditional CO 2 heat pump system. The CO 2 HP DMS system using STD-FCU as heating terminal shows superior economical efficiency to traditional system, with levelized annual total cost reduced by 7.51–15.27%. 

District heating is a well-established technology; however, the use of individual heat pumps has been expanding and is now the main competitor to district heating. The prices for both electricity and district heating often vary over time because of the variation of raw material prices in the marketplace. Consequently, for the building owner it would be cost effective if they had the possibility to integrate both district heating and heat pumps. Aiding in the flexibility to switch between the two systems in order to choose the one with the lowest operating cost throughout the year. In the presented work, the modeling and control of a detached house integrated with both district heating and a heat pump are developed. The operating costs of both systems are computed considering the marketplace prices and the coefficient of performance of the heat pump, related to the external temperature. The results show that heat pumps can be well exploited during the spring and fall to cover base loads, and in the summer can be used for ambient cooling.

Near Infrared spectroscopy has been recently applied in predicting the different materials especially chemical properties of raw wood used in the pulp and paper mills. In this research, the main goal was to estimate wood chemical properties in the chemical pulping at BillerudKorsnäs mill in Gävle. In fact, the quantity of moisture and lignin was measured using a standard method in the laboratory. Then, with near infrared spectroscopy (NIR) data from solid wood, a model was developed to predict moisture and lignin content in the wood chips. Moreover, the yield of digesting process as well as pulp Kappa value were analyzed for the samples taken from the mill.Good calibration models were separately created for Acid Insoluble Lignin (AIL), Total Lignin, Pulp Yield, and Kappa number of pulp using Orthogonal Signal Correction (OSC) treated NIR spectra with the R-Square values of 0.92, 0.89, 0.85, and 0.99, respectively. The model developed for moisture content showed low R-Square value of 0.52, which indicates some over or under estimation in prediction and high calibration errors. So, it cannot be reliably used for prediction. Moreover, Acid Soluble Lignin (ASL) calibration results with R-Square value of 0.077 were poorly correlated with the laboratory measured values.Based on the results, the OSC treated NIR spectra from raw solid wood can be used to estimate AIL and total lignin content as well as pulp yield and Kappa number. These models could be applied to the fiber lines 1 and 2 at the mill to control the pulping process efficiently and increase the pulp quality. However, the reliability of them needs to be analyzed before application.

The global energy system is undergoing a transformative change towards renewable energies. The share of Renewable Energy Sources (RES) and bioenergy in the world’s primary energy use has increased in the recent years. Based on the EU Roadmap 2050 energy plan, the share of renewables in final energy use in Europe will reach at least 55%, a 45% increase from its share today.

Due to the intermittent energy supply from renewables, their high penetration in energy systems can jeopardize the system flexibility, in terms of the balance between energy demand and supply. Lack of system flexibility could cause energy curtailments, increase system costs, or make renewables unreliable sources of energy. Moreover, the expansion of the renewable energy supply could influence the operational strategy of existing energy systems like Combined Heat and Power (CHP) plants. Therefore, the current study focuses on increasing system flexibility of a CHP-dominated regional energy system with increased renewable power supply. Two flexibility options, including a polygeneration strategy and large-scale energy storage using power-to-gas technology, were modelled. The system is then optimized using a Mixed Integer Linear Programming (MILP) method to investigate the production planning of CHP plants in a renewable-based energy system with higher level of flexibility. Different technical and market factors could influence the results of the optimization model, and thereby system flexibility. Thus, the study is carried out under various scenarios for better understanding of the future challenges regarding energy supply, market prices, and climate change.

The investigation provides an increased knowledge of production planning for the existing CHP plants with increased interaction with renewables. Based on the overall observations of this thesis, the proposed power storage system contributes to the increased system flexibility. However, the study suggests polygeneration and integration strategy as the optimal pathway to increase RES penetration and to support system flexibility, considering future energy developments and changes in energy demand and supply.