Choosing the Right Technologies – A Model for Cost Optimized Design of a Renewable Supply System for Residential Zero Energy Buildings

Christian Milan

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

Resumé

Denne afhandling præsenterer en metode til at identificere og undersøge det kost- økonomisk optimale design af energiforsyningssystemer til lav- og nulenergibygninger (Net Zero Energy Buildings) med særligt fokus på enfamiliehuse. En indledende analyse, som undersøger relevant litteratur og eksisterende modelleringsværktøjer, viser, at der for det konkrete fokusområde mangler tilstrækkelige metoder. Baggrunden for anvendelsen af lineær programmering og softwareplatformen GAMS beskrives kort. Efterfølgende forklares koncept og struktur for metoden med de nødvendige input og de resulterende output. Det teoretiske afsnit beskriver det generelle formelsæt for metoden og opsummerer de væsentlige parametre til beskrivelse af individuelle energiteknologier.

Næste kapitel giver en detaljeret beskrivelse af hver enkel energiforsyningsteknologi med relevante økonomiske og tekniske data. Desuden defineres modeller for ydelsen af hver enkel teknologi. I et system i husholdningsskala er varmtvandslagertanken en af de væsentligste komponenter som forbinder forbrug og forsyning og virker som buffer i perioder med tidslig forskydning mellem forbrug og produktion. Derfor er modellen for varmtvandstanken relativt detaljeret med tre forskellige temperaturniveauer, to forskellige forsynings- og forbrugs sløjfer såvel som individuelle varmetab. Denne model præsenteres i slutningen af teknologikapitlet. Efterfølgende valideres metoden i et casestudy ved at undersøge outputtet og dermed ydelsen af hver enkel teknologi på et givet tidspunkt. Heraf kunne der sluttes at de resulterende energiproduktionsrater dækker et realistisk interval i henhold til ydelses modeller defineret gennem herværende afhandling.

Som alternativ til validering af den foreslåede metode er der, som del af dette arbejde, opbygget en eksperimentel opstilling som repræsenterer de fleste af de undersøgte teknologier og som giver mulighed for sammenligning af ydelsen under virkelige og forskellige driftsforhold. Dog var det ikke muligt at få den eksperimentelle opstilling sat i drift indenfor tidsrammen for denne afhandling. Opstillingen er kort beskrevet i kapitel 5. Dette efterfølges af et resumé af hovedresultaterne fra forskellige case studier som er publiceret og præsenteret som en del af denne afhandling. Det konkluderes at en lempelse af kravet om lokal 100 % nettoenergiforsyning medfører en reduktion i de samlede omkostninger og at et optimalt lokalt system ikke nødvendigvis er en interessemodsætning til et fælles forsyningsnet. Desuden viser resultaterne at en antagelse af konstante virkningsgrader for kraftvarmeteknologier ikke medfører større ændringer i beslutningsgrundlaget for investeringer. Dog kan overvejelser omkring fleksible virkningsgrader være vigtige ved optimering af driftsparametre for et eksisterende system som inkluderer brændselsceller, da dellast drift af disse havde en moderat indflydelse på den optimale løsning i de udførte case studies. Endelig præsenteres en metode som tager højde for usikkerheder i form af brugeradfærd og vejrforhold.
OriginalsprogEngelsk
ForlagDepartment of Energy Technology, Aalborg University
Antal sider138
ISBN (Trykt)978-87-92846-39-6
StatusUdgivet - 1 mar. 2014

Fingeraftryk

Water tanks
Costs
Optimal systems
Heat losses
Linear programming
Fuel cells
Temperature
Uncertainty
Optimal design

Citer dette

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abstract = "This work presents a methodology to identify and investigate the cost optimal design of supply systems for Low and Net Zero Energy Buildings with the focus on residential single family houses. A preliminary analysis investigating relevant literature and existing computer tools resulted in the conclusion that for this specific scope a lack of adequate approaches existed. It is briefly discussed, why linear programming and the software platform GAMS have been chosen to define the optimization problem. In the following the concept and structure of the methodology is explained with the main required input data and resulting outcomes. The theoretical part describes the general equations of the approach and summarizes the parameter set, which is applied to model individual technologies.The next chapter describes each considered supply option in detail with relevant cost and technical data. Further, individual performance models are defined. For small scale residential systems the hot water tank is one of the main components, connecting supply and demand side and acting as a buffer during mismatch periods. For this reason, the developed hot water tank model is rather detailed accounting for three different temperature layers, two different supply and demand loops as well as individual heat losses. It is presented at the end of the technology chapter. Subsequently, the methodology is validated by investigating the output with one single technology at a time and thus the individual performance models in a case study. It is found that resulting energy generation rates are in reasonable ranges and according to the performance models defined throughout this work.As an alternative option to validate the proposed methodology an experimental setup has been designed as a part of this work, which features most of the investigated technologies and would allow the comparison with performance under real conditions and different consumption patterns. However, the setup could not be taken into operation within the timeframe of this thesis but is briefly described in Chapter 5. This is followed by a summary of the main findings obtained during different case studies and which have been published and presented as a part of this thesis. It was concluded that lowering the 100{\%} Net ZEB demand would lead to a reduction of overall system costs and that local optimal system solutions do not necessarily contradict with public grid interests, when the control is adapted. Further, results show that the assumption of constant efficiencies for CHP technologies does not lead to large changes in investment decisions.However, considering flexible efficiencies might be important when optimizing operational schedules of an existing system involving fuel cells as their part load operation played a moderate role in the optimal solution of the conducted case studies. Additionally, a method is presented, which accounts for uncertainties in user behavior and weather profiles.",
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Choosing the Right Technologies – A Model for Cost Optimized Design of a Renewable Supply System for Residential Zero Energy Buildings. / Milan, Christian.

Department of Energy Technology, Aalborg University, 2014. 138 s.

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

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