Dissertations / Theses on the topic 'Energy Payback Time (EPT)'

Four solar cells dominate the Swedish market today and are divided into two groups; first generation and second generation. The first generation involves of two silicone solar cells called mono-and multicrystalline solar cells. These solar cells were, as the name indicates, first on the market and today receive the highest efficiency. Due to high manufacturing costs, the second generation was developed which became thin film solar cells. The two most common solar cells in that generation are CdTe and CIGS, which account for about 20 percent of the solar cell market today while the first-generation accounts for the remaining 80 percent. Going towards a sustainable future it’s important and clear that both companies, cities and countries are ready meet the challenges. The solar cell technology has gained high confidence to bring in sustainable electricity production. Investors in Sweden experience the lack of a valuation concept from an environmental perspective between the solar cells on the Swedish market. The study has examined how the four different solar cells affect different environmental categories and which materials in the solar cells that are the most critical. By simulating the electricity production for a year with Gothenburg's solar radiation, the amount of electricity that could be used or sent to the grid was obtained. Where the silicon solar cells that have the highest efficiency also received the most electricity per square meter of solar cell. After producing electricity production and electricity consumption, the energy repayment period was calculated. Through LCA, 11 different environmental categories were developed to analyze different areas that are affected by solar cell production. Aquatic ecotoxicity of the marine environment was the environmental category that was most affected by the production for all four solar cell types. From the environmental category Global Warming, the amount of carbon dioxide equivalents was studied and then a payback time was calculated. Solar cells generally have three different phases; manufacture, operating and waste. The use phase is considered to be almost emission-free, the waste phase is relatively new for solar cell technologies. This is because no large waste streams have come than when the first major investments took place only in the nineties. The solar cells need different techniques depending on the type. The strategies should be different as different parts should be recycled and reused as far as possible. Due to the fact that there is unstable waste management, this phase has not been studied but only the manufacturing phase.   A square metered solar cell was analyzed. For photovoltaic production in Europe, multicrystalline solar cell panels pay back the carbon dioxide equivalents after 11.5 years, while monocrystalline solar cell panels pay again after 14.3 years, ie after about half the life. CdTe paid the carbon dioxide equivalents fastest, after 2.2 years, and CIGS after 3.6 years. This means that the thin-film solar cells have the fastest time to get minus emissions. It is not justified to invest in solar cells manufactured in China when operating in Gothenburg, only after studying solar cell production. When the repayment period for carbon dioxide equivalents has been calculated, a Nordic electricity mix has been calculated with, depending on which electricity mix is ​​chosen, it either gives reasons to not invest or to invest in solar cells. It is therefore important to be clear about what use the solar cells will have and which electricity is actually replaced before investors decide whether solar cells are the right energy source to invest in.

This paper discusses the average energy savings of various smart devices in connection with their average price. By calculating the devices' payback times, a ranking of the tools can be given. The whole study focuses on the average household within the EU-28 in terms of climate as well as in terms of user behaviour. The purpose of the research was to provide a win-win situation for users' wallets and the environment by showing the device which suits both players best. As a result of the research, it was found that the greatest reduction in energy consumption can be reached by an interaction of the smart device and the inhabitants of a smart home. By giving users feedback on their energy consumption through smart meters, average savings of 7.5% are reached. As a smart meter is available for about Euro 80, it has a payback time of only 4.24 months.

I dagens samhälle är energi av essentiell vikt. Energi behövs för transport, elektricitet och uppvärmning. Fossila bränslen, som är en begränsad resurs, är idag den dominerande energikällan som används. Allteftersom indu-strier och konsumenter världen över använder mer energi för vardag blir det allt viktigare att belysa hur viktigt det är att minska på den globala efterfrågan på energi. Fossila bränslen behöver ersättas med förnyelsebara energikällor, såsom sol-, vind- och tidvattenkraft, för att samhället ska uppnå en hållbar utveckling.När en ny produkt utvecklas är det viktigt att analysera den potentiella miljöpåverkan, förslagsvis genom att genomföra en livscykelanalys, innan tillverkningen tar vid. Deep Green, som är en enhet som drivs med hjälp av tidvatten varefter elektricitet genereras, är en produkt som befinner sig i ett initialt skede av produktutveckling-en. I den här rapporten har en livscykelanalys sammanställts på hela produkten med syftet att uppnå en analys av hur olika val av material påverkar energianvändningen, koldioxidutsläppen och energiåterbetalningstiden. Komponenter har jämförts med varandra för att fastställa vilken komponent hos Deep Green som bidrar mest till energianvändningen och koldioxidutsläppen. Utöver en livscykelanalys, LCA, har en digital modell, skapad i ett Excel dokument, utvecklats för att underlätta beräkningar av energianvändning, koldioxidutsläpp och ener-giåterbetalningstid. Den digitala modellen, med namn ENCO©, erbjuder möjlighet för användaren att ändra och definiera materialval för varje enskild komponent för att således utvärdera den potentiella miljöpåverkan samt energiåterbetalningstiden. Deep Green består av 34 olika komponenter som alla ingår i den genomförda LCAn men en initial analys visar att bara tolv specifika komponenter bidrar störst till energianvändningen och koldioxidutsläppen. Fundamentet och vingstrukturen står för 78 % respektive 15 % för energianvändningen samtidigt som tio andra komponenter tillsammans utgör sex ytterligare procent. Resterande 27 komponenter delar på den sista procenten. Givet materialen som företaget Minesto har bistått med uppgår den totala ener-gianvändningen och koldioxidutsläppen för hela produkten till ungefär 4500 GJ respektive 342 ton. Fundamen-tet är den del av Deep Green som bidrar mest till den potentiella miljöpåverkan.Beroende på de definierade materialen för varje komponent varierar energiåterbetalningstiden mellan 220 och 260 dagar vilket betyder att en produktion av Deep Green vore lönsam. Dock har den genomförda LCAn flera begränsningar som borde beaktas innan ett sista beslut fattas.Den resulterande energiåterbetalningstiden, EP, bör användas försiktigt och presenteras ihop med system grän-serna då de påverkar energiåterbetalningstiden mycket. Den totala energianvändningen och koldioxidutsläppen beror starkt på val av hantering när produkten är uttjänt. Baserat på resultatet, rekommenderas att fundamen-tet lämnas på havsbotten i slutet på livscykeln för att få lägst energiåterbetalningstid.En undersökning om huruvida det är möjligt att placera hela produktionskedjan i ett utvecklingsland, såsom Tanzania, har också blivit genomfört jämsides med LCAn. De flesta råmaterial, som är nödvändiga för tillverk-ning av Deep Green, bryts i Tanzania. Det är dessutom möjligt att importera de material som inte finns tillgäng-liga lokalt i landet. Med Tanzania som land kommer energiåterbetalningstiden att bli högre jämfört med Sve-rige eller England eftersom fler komponenter behöver importeras som i sin tur genererar en ökning av transpor-ter.När Deep green är färdigutvecklad rekommenderas att en ny beräkning av energiåterbetalningstid och koldiox-idutsläpp göras. ENCO© kan med fördel användas till detta. Det rekommenderas även att distributionskablar och installation inkluderas.
Energy is an essential asset in the present society. It is needed for transportation, electricity and heating. Fossil fuels, being a limited reserve, are presently the dominating resource from which energy is being used. As indus-tries and consumers around the world use more energy for each passing day it becomes vital to shed some light on how important it is to decrease the global energy demand. Fossil fuels are needed to be replaced by renewa-ble energy sources, such as solar and wind power, in order to obtain a more sustainable development.When a new product is being developed it is usually important to analyze the potential environmental impact, suggestively by conducting a life cycle analysis, prior to manufacturing. Deep Green, being a tidal energy device for generation of electricity, is a product in its initial developing stage. In this thesis a lifecycle assessment has been conducted of the complete product with the purpose of achieving an analysis of how different choices of materials affect the energy usage, CO2 footprint and the energy payback time. Identifications by comparison have been taken into account to determine which component of Deep Green that contributes mostly to the energy usage and CO2 footprint. In addition to the Life Cycle Assessment, LCA, a digital model, created in an Excel workbook, has been developed to simplify calculations of the energy usage, CO2 footprint and energy payback time. The digital model, namely ENCO©, provides the possibility to interchange choice of materials for each component in order to evaluate the potential environmental impact and the energy payback time. Deep Green consist of 34 different components which are included in the LCA but an initial analysis shows that only twelve specific parts contribute largely to the energy usage and the CO2 footprint. The foundation and the wing structure account for 78 % and 15 % respectively of the energy usage along with ten other parts which together stand for an additional 6 %. Remaining 27 parts share the final percentile. Given the materials provided by the company of Minesto the total energy usage and CO2 footprint for the complete product corresponds to approx-imately 4500 GJ and 342 tonne respectively. The foundation is the part of Deep Green that contributes most to the total environmental impact.Depending on the defined materials for each component the energy payback time varies between 220 to 260 days which is to say that a production of Deep Green would be profitable. Nevertheless the conducted LCA has several delimitations which should be reflected upon prior a final decision is made.The resulted Energy Payback time, EP, should be carefully used and presented with the system boundaries, since they affect the EP very much. The outcome of energy consumption and CO2 footprint, depend highly on the choice of end of life management. Based on the result it is recommended that the foundation is left on the sea-bed at the end of its lifecycle to obtain the best EP.An investigation of whether it is possible to position the complete supply-chain within the boundaries of a de-veloping country, namely Tanzania, has also been conducted along with the LCA. It is believed that most of the raw materials, which are necessary for the manufacturing of Deep Green, are mined in Tanzania. It is however possible to import those materials which are not available within the country. When considering Tanzania, as a point of implementation for Deep Green, the energy payback time will become higher compared to Sweden or England since more components need to be imported which in turn generates an increase of transportation.It is recommended that a new calculation of the EP and the carbon footprint are done when Deep Green is fully developed. ENCO© can advantageously be used for this. It is also recommended that the distribution cables and the installation are included.

In the current global market, there are plenty solutions for the savings of energy in the different areas of consumption in buildings: Green roofs and walls, cool roofs, daylighting, motion sensors, and others but there are very few sources of renewable energy at the reach of a common person in residential (smaller) scale. Photovoltaic systems are the most well-know and reliable process of harvesting energy at this small scale. The relationship between energy demand and energy production when installing a photovoltaics system in a residence is one of the main drivers while making a decision at the time of purchasing a system. However, architectural decisions in early stages may influence, enhance or even decrease the possible energy generation and interior performance, thus influencing the possible return of investment. This study evaluates the possible architectural variations that may be beneficial or disadvantegous at a particular city and other circumstances. From, roof, angle, location, roof articulation, layout articulation , shading devices and others, this paper shows a spectrum of convenient and inconvenient projects due to current conditions like climate, solar radiation, typical construction, electricity rates and government incentives. As a conclusion a hierarchy of architectural elements when being used with photovoltaics is developed to demonstrate that a common user can strategically play with architectural features of his/her house to take the most out of the system.

The paper at hand presents the environmental impact analysis of a photovoltaic (PV) power station sited in Stockholm, Sweden, using life cycle assessment (LCA). The LCA considers the primary energy return on investment and global warming potential of the PV-station, including; resource extraction, manufacturing, transportation, operation and maintenance, and decommissioning. Other environmental impact indicators are also presented, such as; the eutrophication, acidification, human toxicity, and ozone depletion potentials. The results show that the most critical phase of the lifecycle is the upgrade from metallurgical to solar grade silicon due to the high consumption of energy. The emissions results are compared to the emissions factors used for calculations in Sweden in accordance with the Swedish Energy agency and the European Commission’s directive for emissions calculations. The results for the other environmental indicators showed inconsistencies compared to existing studies, something that is according to the IEA’s guideline for PV-systems LCA caused by data scarcity and the indicators lacking consensus within the PV LCA-community. The studied PV-station is expected to reach energy neutrality after 2,4 years and offset annual GHG emissions of up to18 ton of CO 2 equivalents.
Studien tillhands presenterar miljöutvärderingen av en fotovoltaisk solcellsanläggning i Stockholm. Detta utfördes med hjälp av livscykelanalysverktyget. Analysen använder energiåterbetalningstiden och den globala uppvärmningspotentialen som indikatorer på anläggningens miljöinverkan. Både återbetalningstiden och den globala uppvärmningspotentialen beräknas för gruvarbetet, transporten, drift och underhåll samt avveckling och bortskaffning av anläggningen. Överföringsförluster beräknas också över anläggningens livscykel. Andra indikatorer som beräknas i denna studie är potentialen för försurning, övergödning, ozonnedbrytning och humantoxicitet. Dessa beräknas endast för modulens tillverkningskedja. Studiens resultat visar att den mest kritiska processen under solcellsanläggningens livscykel är kiselmetallens omvandling till solkisel, detta med avseende på energiförbrukningen och utsläpp av växthusgaser. Anläggningens globala uppvärmningspotential uttrycks i växthusgasutsläpp och jämförs med den nordiska elmixens utsläppsfaktor. Jämförelsen görs enligt dem gällande EU-direktiven. Resultaten för dem andraindikatorerna har visat på väsentliga avvikelser jämfört med tidigare studier. Detta beror enligt det internationella energirådet på databrist och på att dessa indikatorer saknar stöd inomLCA samfundet. Solcellsanläggningen beräknas bli energineutral efter 2,4 år samt eutralisera utsläpp på upp till 18 ton koldioxidekvivalenta per år.

Analytical, closed-form solutions governing thermoelectric behavior are derived. An analytical model utilizing a thermal circuit is presented involving heat transfer into, through, out of, and around a thermoelectric device. A nondimensionalization of the model is presented. Linear heat transfer theory is applied to the model to obtain a series of closed form equations predicting net power output for the thermoelectric device. Fluid streams flowing through shrouded heat sinks with square pin fins are considered for the thermal pathways to and from the device. Heat transfer and pressure drop are characterized in a manner conducive to an analytical model using previously published experimental results. Experimental data is presented which validates and demonstrates the usefulness of the model in predicting power output for commercially available thermoelectric generators. A specific design for a thermoelectric power harvester is suggested consisting of a pattern of thermoelectric generators. An economic model for calculating payback time is developed. An optimization process is demonstrated that allows for the payback time of such a system to be minimized through optimization of the physical design of the system. It is shown that optimization of the thermal pathways dramatically reduces payback time. Optimized design of a system is discussed in light of theoretical cases with feasible payback times.

This thesis is a study on how Mutanda Eco-Community   Centre (MECC) in the south western part of Uganda can harness the solar   energy at their disposal using photovoltaic as compared to the using of   conventional energies in producing the needed electricity at the centre and   the impacts on climate change. Since the centre is used in education on   climate change mitigation and adaptation measures, it is expected that   anything the centre does or uses with regards to energy ought to come from   renewable sources such as wind, solar, thermal and biomass. Electricity has   been a great challenge because there is no access to the national electricity   grid. Since there is much abundance of solar irradiation in the entire   country, solar poses as a potential sustainable energy since it is a   renewable energy and has the greatest environmental benefits. The objective   is in two categories: to determine how feasible the photovoltaic technology   is in Kisoro and its application at MECC and to analyse the effects on   climate change with comparison with non-renewable sources of energy. To   determine the above, both qualitative and quantitative methods were used.   Results from the studies through the use of simulation method (PVGIS-5)   indicate that Kisoro, where the centre is located, has solar irradiation to   harness due to Uganda´s geographical location on the equator. Findings   revealed there are feasible governmental and private policies, market for PVs   systems, enough players in the Sector and the willingness of the people to   adopt and use solar energy, and its markets economic studies do reveal to be   the indicators for the feasibility of the technology in Kisoro. Corrections   of a few bottlenecks will increase the adoption rate of the photovoltaic   systems. An investment of 85,000, 000 UGX will aid a financial benefit of   4,569.40 UGX per each kWh of electricity generated with 3.1years of Energy   Payback Time and will prevent environmental pollution when compared with   non-renewable energy. Climatic effects are minimal as compared to the other   sources of energy. This greenhouse gases emission comes during the production   of the PVs, modules and systems. The usage of solar technology possesses a   lot of advantages. It is an unlimited source of energy; its maximum usage   reduces carbon dioxide emissions. International conflicts of ownership of   source of conventional energies are reduced and solar power creates energy   security and dependency.

2018-12-07

The subject of this thesis is the analysis of the evaluation of a construction unit by reducing its energy intensity. The first part of the thesis is dealing with the theoretical explanation of the basic concepts that are necessary for understanding of the dealt problem. The next part is dealing with the methodics of calculation of a building energy efficiency, determination of market prices of the property by general methodology, solution of the budgets of the reconstruction possibilities and determination of payback time of the investment into the reconstructions. The result of the thesis is the summary of all the outputs into the detailed table with comments.

Studien syftade till att ge en rekommendation angående hur fjärrvärmebolaget Stockholm Exergi bör utforma sin framtida strategi beträffande fasta oförädlade skogliga biobräanslen. Genom litteraturstudier och intervjuer utreddes dessa bränslens konkurrenskraft utifrån perspektiven klimatneutralitet, politiska direktiv och styrmedel, leveranssäkerhet samt lönsamhet. Resultatet visade bland annat att användningen av grenar och toppar kan medföra klimatnytta. Vidare framkom att implementeringen av EU:s nya förnybartdirektiv inte kommer att ha storskalig påverkan på Stockholm Exergis framtida användning av dessa bränslen. Gällande leveranssäkerhet och lönsamhet påvisades exempelvis en större framtida efterfrågan på skogliga restprodukter från andra sektorer. Ändock kunde slutsatsen dras att skogliga biobräanslen, under vissa förutsäattningar, har en viktig roll i Stockholm Exergis framtida fjärrvärmeproduktion.
The study aimed to give a recommendation regarding how the district heating company Stockholm Exergi should design their future strategy concerning unprocessed solid woody biofuels. Through literature studies and interviews, the competitiveness of the fuels has been assessed based on climate neutrality, political directives and instruments, security of supply as well as profitability. Among other things, the results showed that the use of tree branches and tops can imply positive climate effects. Furthermore, the implementation of EU's new renewable energy directive will only have a marginal impact on Stockholm Exergi's future use of woody biofuels. Regarding the security of supply and profitability,an increased future demand of forest residues in other sectors have been identified. However, the study concludes that, under certain circumstances, woody biofuels have an important role in Stockholm Exergi's future district heating production.

To be able to mitigate the climate change and disasters that will come with it and to ensure economic growth, there is a need for change. A good start is more renewable energy and less harmful emissions. It is known that solar energy is sustainable and made from an endless source, the sun. However, it is not known how much impact the photovoltaic solar panels have through its entire lifecycle, from extraction of raw materials to End of Life management. This study has investigated photovoltaic solar panels' full life cycle to see how sustainable they really are. Including where the biggest opportunities for improvement of environmental, financial and social sustainability within the value chain is found. The results have been obtained by conducting a literature study, interviews with people with expertise of different parts of the value chain and finally calculations have been made to compare and visualize the findings. Two main ways to improve the PV panels’ negative impact in terms of environmental, financial and social sustainability have been established. Firstly, the study suggests the importance of implementing advanced recycling within the value chain. Recycling a high percentage of materials in the PV panel, and reusing the recovered material in production will decrease the energy consumption and harmful emissions significantly, alongside increasing circularity of critical materials and bring both financial and social benefits. Secondly, moving the better part of the production to Europe from China would also decrease the negative impact of the PV panels, especially the environmental and social impact, the study could however not find sufficiently good arguments for financial improvement to move the production to Europe. To be conclusive, this subject would need further studies.
För att kunna lindra klimatförändringar och de medföljande katastroferna och säkerställa den ekonomiska tillväxten finns det ett stort behov av förändring. En bra start är att använda mer förnybar energi och som bidrar till färre skadliga utsläpp. Det är känt att solenergi är hållbart med bränsle från en oändlig källa, solen. Det är emellertid inte känt hur stor påverkan solcellspanelerna har under hela dess livscykel, från utvinning av råvaror till dess panelens liv är över. Denna studie har undersökt solcellspanelernas hela livscykel för att se hur hållbara de egentligen är. Studien har även studerat var de största möjligheterna för förbättring av miljömässig, finansiell och social hållbarhet inom värdekedjan finns. Resultaten har erhållits genom att genomföra en litteraturstudie, intervjuer av personer med expertis inom olika delar av värdekedjan och slutligen har beräkningar gjorts för att jämföra och visualisera resultaten. Två huvudsakliga sätt att förbättra solpanelernas negativa påverkan när det gäller miljömässig, ekonomisk och social hållbarhet har identifierats. För det första föreslår studien vikten av att implementera avancerad återvinning inom värdekedjan. Återvinning av en hög andel material i solcellspanelen och återanvändning av det återvunna materialet i produktionen kommer att minska energiförbrukningen och skadliga utsläpp avsevärt samt förbättra cirkuläriteten av kritiska material och medföra både ekonomiska och sociala fördelar. För det andra skulle förflyttning av den större delen av produktionen till Europa från Kina också minska de negativa effekterna av solcellspaneler, särskilt de miljömässiga och sociala effekterna, studien kunde dock inte hitta tillräckligt med goda argument för att en förflyttning av produktionen till Europa skulle leda till en ekonomisk förbättring. För att detta ska vara avgörande skulle detta ämne behöva ytterligare studier.

This Master´s thesis deals with the analysis of the effectiveness of ventilation systems. The key concept of the thesis is HVAC system in buildings with low energy demand. In the most comprehensive chapter are some concepts clarified: air tightness, ventilation, air conditioning, heating and hot water preparation. The aim of the thesis is to define passive house in terms of acquisition and operating costs, including the ventilation system and to make comparison with systems applied in conventional construction with focusing on assessment of effectiveness of ventilation equipment.

The aim of the master thesis is the assessment of the economic effectivity of thermal insulation with the state incentives in the Czech Republic and Slovak Republic. In the master thesis, the issue of investment, the possibilities of state funding of the construction industry, a detailed analysis of national funding programs aimed at promoting thermal insulation and the characteristics of thermal insulation contact system will be discussed with the focus on the design, realization management of the building and material possibilities. The output of the master thesis will be a proposal of a possible solution of thermal insulation contact system on a reference object. The financing of the investment will be compared in case of investment based on own resources or a bank loan, with the final assessment of economic efficiency with the use of insulation subsidy programs in the Czech Republic and Slovak Republic.

Baigiamajame magistro darbe nagrinėjamos decentralizuoto (paskirstytojo) generavimo ir atsinaujinančių energijos išteklių panaudojimo sprendimai, aprūpinant pastatą įvairia energija – šiluma, vėsa, karštu vandeniu, elektra. Energija aprūpinama panaudojant tokius įrenginius – kogeneratorių, kompresorinę ir absorbcinę šaldymo mašinas, saulės kolektorius, dujinį katilą. Apibūdinami pasirinkti įrenginiai, jų veikimo principai, savybės, atskleidžiami jų privalumai ir trūkumai. Parengiamos trys alternatyvių variantų principinės energijos sistemų schemos, suformuotos iš minėtų įrenginių derinių. Pristatomi šių alternatyvių įvairios eneregijos gaminimo variantų galios ir energijos kiekių rodikliai. Parenkamas optimalus naujų technologijų derinys. Alternatyvių variantų ekonominis pagrįstumas įvertinamas, parenkant optimalų energijos generatorių derinį atsižvelgiant į jų bendrą atsiperkamumą. Apibendrinus teorines žinias ir gautus skaičiavimo rezultatus, pateikiamos baigiamojo darbo išvados ir pasiūlymai. Darbą sudaro 6 dalys: įvadas, teorin�� dalis, analizinė dalis, ekonominė dalis, išvados ir pasiūlymai, literatūros sąrašas. Darbo apimtis – 61 psl. teksto be priedų, 34 iliustr., 11 lent., 46 literatūros šaltiniai. Atskirai pridedami darbo priedai.
Solutions of decentralized (distributed) production and application of renewable energy sources in the case of different energy - like heating, cooling, hot water, electricity - supply for a building were analyzed in the final master thesis work. Energy supply sources are cogenerator, compressor and absorption cooling machines, solar collectors, gas boiler. Selected devices, their principles of work, characteristics, their advantages and disadvantages were described. Three schemes of principal energy system alternative were described, using combinations of devices mentioned above. Power and energy amount indexes of different energy generating alternatives were specified. The optimal combinations of new technologies were selected. After the optimal combination of energy generating system was done, economical validity of alternatives were estimated taking into account their total payback time. After theory and received results were summarized, the conclusions and suggestions were presented in the end of the final master work. Work consists of 6 parts: introduction, theory, analysis part, economical part, conclusions and suggestions, literature source. Size of Work: 61 pages of text excluding the appendixes, 34 pictures, 11 tables, 46 literature sources. Appendixes of the work are attached separately.

Dagens behov för energieffektivisering ställer höga krav på industrisektorn som anses vara den största energikonsumenten. Holmen AB är verksam inom massa- och pappersindustrin som är en energiintensiv bransch där sådana stora energianvändare som pumpapplikationer spelar en nyckelroll i produktionen. Denna studie genomfördes för att hjälpa företaget att undersöka vilka energi- och kostnadsbesparingar som kan förväntas om det befintliga pumpreglersättet ändras. Syftet med arbetet var att ta fram en metod för uppskattning av pumpenergiförbrukning, som skulle producera ett underlag för en jämförelseanalys av energiförbrukningen vid olika reglersätt. Studien fokuseras mest på centrifugalpumpar, som dominerar i industriell miljö på grund av sin robusta konstruktion, höga effektivitet och relativt låga behov för underhåll. Men det tillvägagångssätt som har använts i studien kan användas för bedömning av olika typer av pumpar och reglersätt eftersom det byggs på de grundläggande fluidmekanikslagarna. Tidigt i arbetet identifierades de viktiga parametrar som mest påverkar energiförbrukning i centrifugalpumpar och som krävs i beräkningar. Olika reglersätt diskuterades utifrån den befintliga litteraturen och forskningen. Uppskattning av energiförbrukning och energikostnader utfördes för två olika reglersätt, strypreglering och frekvensreglering. I arbetets sista skede jämfördes resultaten för de två reglersätten för att avgöra om det finns en potential för energi- och kostnadsbesparingar vid byte från strypreglering till frekvensreglering. Studiens resultat visar att övergång till frekvensreglering kommer att medföra energibesparingar och som följd besparingar i årliga driftkostnader samt LCC-kostnader. Storleken på besparingarna beror på minskning i varvtalet. Frekvensregleringen är mest lönsam då det önskade flödet skiljer sig mycket från det nominella flödet i systemet, men eventuell försämring av motor- och pumpverkningsgrad måste tas i beaktande. En mer utförlig analys av energiförbrukning vid olika flöden och olika typer av medier rekommenderas att utföras med användning av praktiskt uppmätta effektförbrukningsvärden.
Today's need for energy efficiency places high demands on the industrial sector, which is considered to be the largest energy consumer. Holmen AB is a pulp and paper producer. Pulp and paper production is an energy-intensive branch where pump applications consume large amounts of energy while playing a crucial role in the production process. This study was conducted to help the company investigate what energy and cost savings can be expected if the existing pump control method is changed. The purpose of the study was to develop an approach for estimating pump energy consumption, which would produce a basis for comparative analysis of energy consumption for different control methods. The study focuses mainly on centrifugal pumps, which dominate the industrial environment due to their robust construction, high efficiency, and relatively low maintenance needs. However, this study's approach can be used to assess different types of pumps and control modes as it is based on the fundamental fluid mechanics laws. At the beginning of the study, the key parameters that affect energy consumption in centrifugal pumps were identified to be later used in calculations. Pump control methods were discussed based on the existing literature and research. Estimation of energy consumption and costs was performed for two different control methods, throttle control, and frequency control. In the last stage of the study, two control methods were compared based on the energy consumption calculation to determine whether there is a potential for energy and cost savings when switching from throttle control to frequency control. The results show that usage of frequency control would lead to energy savings and, therefore, to savings in annual operating costs and LCC costs. The amount of the savings depends on the reduction in the rotational speed of the motor. The frequency control is most advantageous when there is a significant difference between the desired flow and the nominal flow in the system. But the potential reduction of motor and pump efficiency must be taken into consideration. A more detailed analysis of energy consumption for different flows and different types of pulp is recommended, with practically measured energy consumption values.

Tese de Doutoramento em Sistemas Sustentáveis de Energia, apresentada ao Departamento de Engenharia Mecânica da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Traditionally, energy planning in developing Asian countries has neglected the structure of energy demand and how it is likely to evolve as development takes its path. Furthermore, the lack of concern with the conservation of energy and the limited availability of energy consumption data have made it very difficult to assess in a reasonable manner the potential for energy savings in the major energy end-use sectors. Energy planning is thus a challenging task, in particular with the continuous growth of agricultural and industrial activities. Henceforth, an up-to-date review of the main issues at stake regarding the choice of energy efficient technologies in India’s residential sector, bringing to light the main challenges that have to be faced in the design of energy efficiency policies and programs in this country, has been first conducted based on extensive literature research. Since energy efficiency and energy security have a prominent role in the economic and social development of all countries, the formulation of a proper modelling framework that supports decision-makers with the definition of energy policies without compromising future energy needs becomes timely and relevant. From the different approaches available, Input – Output (IO) models are especially useful, since they allow considering different impacts that can be consistent with different energy policy options. In order to assist energy decision-makers of India on the appraisal of the future effects of the replacement of the current business as usual technologies (BAU) with energy efficient best available technologies (BAT), a novel IO modelling framework has been designed by introducing a bottom-up approach into an IO model which is combined with technical data for the holistic assessment of nine energy efficient technologies previously identified. A large size platform of real data has also been gathered considering different data sources, namely the household building stock characterization, the number of operating days according to the climatic regions of India, the lifetime and the investment cost of each equipment. The trade-offs involved in the multi perspective assessment of the technologies under analysis were then evaluated by both considering the economic IO modelling framework developed and an economic analysis specifically addressing the net present value, the savings to investment ratio and the cost of conserved energy (also incorporating the private investor’s concerns). Finally, two modelling formulations were suggested which combine the use of the Economic IO Lifecycle (EIO-LCA) assessment with multiobjective interval portfolio theory to support public decision-makers on the design of programs to foster the investment on energy efficient technologies. Each model considers two objective functions: the maximization of the savings to investment ratio as a surrogate measure of return and the maximization of the minimum deviation of GHG avoided emissions/energy savings of the portfolio during its lifetime from the expected GHG emitted/energy embodied in its manufacture, as a proxy of risk minimization. In order to ensure a certain diversification level of the technologies to be subsidized, constraints were imposed on the maximal amount assigned to the energy efficient technologies under consideration, also assuring a given energy payback time (EPBT)/GHG payback time (GPBT). In this last case, the originality of this work is twofold: on one hand, the energy embodied in each energy efficient technology (EET) under scrutiny has been obtained through national I-O data avoiding the truncation problems usually found in traditional lifecycle inventories; on the other hand, besides the traditional EPBT/GPBT which only accounts for direct energy saving/GHG avoided emission effects, new EPBT/GPBT concepts are introduced which consider indirect and induced energy saving/GHG avoided emission effects. The first and second formulations might be more suitable for countries with higher and lower emission factors regarding their electricity mix, respectively. In addition, a proposal for obtaining the efficient portfolio solutions was also suggested, which allows considering three types of investment strategies, i.e., a conservative strategy (leading to a lower number of subsidized devices), an aggressive strategy (leading to a higher number of subsidized devices) and a combined strategy. Finally, the anticipated economic, energy, environmental and social impacts (E3S) obtained in each solution previously computed are projected.
Tradicionalmente, o planeamento energético em países em vias desenvolvimento, em particular nos países asiáticos, tem negligenciado a estrutura da procura de energia e a sua evolução, num contexto de desenvolvimento económico crescente. Por outro lado, a falta de preocupação com a conservação de energia e a falta de disponibilidade de informação atualizada e detalhada, respeitante ao consumo de energia nestes países, têm dificultado a análise fundamentada do potencial efetivo de poupança energética nos sectores mais intensivos em energia. Neste âmbito, o planeamento energético apresenta diversos desafios, em particular com o crescimento contínuo dos setores de atividade agrícola e industrial. Por conseguinte, foi efetuada uma revisão crítica da literatura atualizada, respeitante às principais tecnologias eficientes de energia utilizadas no sector residencial da Índia, ressaltando os principais aspetos críticos que devem ser contemplados na elaboração de políticas e programas de eficiência energética neste país. Como a eficiência e a segurança energéticas desempenham um papel proeminente no desenvolvimento económico e social de todos os países, a formulação de modelos adequados, que permitam apoiar os decisores, de forma consistente, na definição de políticas energéticas, sem comprometer as necessidades energéticas futuras, torna-se oportuna e relevante. No que diz respeito às diferentes abordagens disponíveis na literatura científica, os modelos de Input – Output (IO) são especialmente úteis, pois permitem avaliar diferentes impactes que podem ser consentâneos com diferentes opções de política energética. Neste âmbito, de modo a apoiar os decisores de política energética da Índia na avaliação dos efeitos potenciais resultantes da adoção de medidas de política que incentivem a adoção de tecnologias energeticamente eficientes, foi proposta uma nova ferramenta metodológica assente em análise IO. O modelo IO foi então ajustado para efetuar a avaliação holística de nove tecnologias energeticamente eficientes previamente identificadas, através de uma abordagem bottom-up que combina dados técnicos com dados económicos. Neste contexto, foi construída uma plataforma de dados reais de dimensão considerável, tendo sido reunida informação proveniente de diferentes fontes de dados, tendo em conta, nomeadamente, a caracterização do parque habitacional, o número de dias em que as tecnologias operam, em média, de acordo com as regiões climáticas da Índia, a vida útil e o custo de investimento de cada equipamento. De modo a ser possível avaliar os trade-offs envolvidos na avaliação multidimensional de cada tecnologia analisada, foi utilizada a ferramenta metodológica anteriormente desenvolvida e foi encetada uma análise económica, contemplando especificamente o valor atualizado líquido, o rácio entre poupança e investimento e o custo da energia conservada de cada equipamento (incorporando também as preocupações do investidor privado). Finalmente, foram sugeridas duas formulações matemáticas que combinam o uso da Análise do Ciclo de Vida IO (ACV-IO) com modelos do portfolio multiobjectivo intervalares para apoiar os decisores públicos na proposta de programas para fomentar o investimento em tecnologias energeticamente eficientes. Cada modelo considera duas funções objetivo: a maximização da relação entre poupança e investimento, como medida de retorno, e a maximização do desvio mínimo entre as emissões de GEE evitadas/energia poupada durante a vida útil do equipamento e os GEE emitidos/energia incorporada nas fases de fabrico e instalação, como proxy de minimização do risco. Com o objetivo de garantir um certo nível de diversificação das tecnologias a serem subsidiadas, impuseram-se restrições ao montante máximo a afetar às tecnologias energeticamente eficientes, assegurando, simultaneamente, um determinado tempo de retorno energético (EPBT)/tempo de retorno carbónico (GPBT). Neste último caso, a originalidade deste trabalho é dupla: por um lado, a energia incorporada em cada tecnologia energeticamente eficiente sob escrutínio foi obtida através de dados IO, evitando os problemas de truncagem normalmente encontrados nos inventários de análise do ciclo de vida; por outro lado, além do tradicional EPBT/ GPBT, que apenas contabiliza os efeitos diretos da energia poupada/emissões evitadas de GEE, são introduzidos novos conceitos de EPBT/GPBT que consideram os efeitos indiretos e induzidos pela poupança energética/emissões evitadas de GEE. A primeira e a segunda formulações podem ser mais adequadas para países com maiores e menores fatores de emissão em relação ao seu mix de fontes energéticas utilizadas na produção de eletricidade, respetivamente. Adicionalmente, foi ainda sugerida uma proposta para obter soluções eficientes, considerando três tipos de estratégias de investimento, isto é, uma estratégia conservadora (conduzindo à subsidiação de um menor número de equipamentos), uma estratégia agressiva (conduzindo à subsidiação de um maior número de equipamentos) e uma estratégia combinada.