Utility-scale photovoltaic & battery storage systems - Techno-economic feasibility study of the new stadium in Freiburg, Germany
Author
Török, Sophie
Term
4. Term
Publication year
2019
Submitted on
2019-06-14
Pages
80
Abstract
Energisektoren står for den største CO2-udledning i EU. For at mindske udledninger vokser brugen af vedvarende energi, men produktionen svinger, når solen ikke skinner eller vinden ikke blæser. Et storskala batterilager kan udjævne disse udsving, men er dyrt og bliver derfor ofte fravalgt. Denne afhandling undersøger, om en storskala tagmonteret solcelleløsning kombineret med et storskala batterilager er teknisk og økonomisk realistisk for en stor elforbruger. Casen er det nye fodboldstadion i Freiburg, Tyskland. I dag dækker en dieselgenerator stadionets elbehov under kampe, mens baseloaden i øvrig drift købes fra elnettet. Som alternativ vurderes et tagmonteret fotovoltaisk (PV) anlæg med batterilager, der både kan erstatte dieselgeneratoren og skabe indtægter. Fordi batteriet skal have høj kapacitet for at kunne forsyne en kamp, men kampe kun afholdes ca. 18 gange om året, kan batteriet i resten af tiden bruges til at lagre og handle strøm. Metoden er at fastlægge stadionets lastprofil (forbrugsmønster) og modellere tre systemer i softwareprogrammet energyPRO: (1) nuværende praksis med dieselgenerator (DG), (2) PV kombineret med diesel (PVDG), og (3) PV kombineret med et storskala batterilager uden diesel (PVBES). For hvert system vurderes den tekniske ydeevne samt investerings- og driftsomkostninger, inklusive elindkøb fra nettet og relevante afgifter og tariffer. Den økonomiske levedygtighed vurderes ved nettonutidsværdi (NPV), som sammenligner fremtidige indtægter og omkostninger i nutidskroner. For PVDG og PVBES indgår enten en feed-in-tarif (fast afregningspris for leveret strøm) eller salg på spotmarkedet (kortsigtet engrosmarked). Derudover afprøves forskellige økonomiske scenarier for PVBES for at forbedre rentabiliteten. Resultaterne viser, at under samme forudsætninger er PV+diesel (PVDG) den økonomisk mest fordelagtige løsning, selv om NPV er negativ for alle tre systemer. PVBES giver til gengæld større fleksibilitet og åbner for ekstra indtægter på balancemarkedet eller via strømkøbsaftaler (Power Purchase Agreements). Med disse muligheder bliver PVBES ikke blot den bedste økonomiske løsning, men udgifterne kan også tjenes hjem på 8–16 år. Derudover medfører driften af PVBES-systemet ingen CO2-udledninger.
The energy sector is the largest source of CO2 emissions in the European Union. To cut emissions, renewable energy is being deployed, but its output fluctuates when there is no sun or wind. Large battery storage can smooth these swings, yet it is expensive and often not considered. This thesis examines whether combining a large rooftop solar photovoltaic (PV) system with a large battery is technically and economically viable for a major electricity user, using the new football stadium in Freiburg, Germany, as a case study. Currently, a diesel generator covers the stadium’s electricity demand during matches, while the base load at other times is supplied from the grid. As an alternative, a rooftop PV plant with battery storage is assessed; this setup can replace the diesel unit and also generate revenue. Because the battery must be sized to power a match but matches occur only about 18 times per year, the battery can be used for electricity storage and trading during the remaining time. The approach is to determine the stadium’s load profile and model three systems in the energyPRO software: (1) the current practice with a diesel generator (DG), (2) PV plus diesel (PVDG), and (3) PV plus a utility-scale battery with no diesel (PVBES). Each system’s technical performance is evaluated, and investment and operating costs are estimated, including grid electricity purchases and relevant surcharges, taxes, and fees. Economic feasibility is assessed with net present value (NPV), which compares future costs and revenues in today’s money. For PVDG and PVBES, either a feed-in tariff (a guaranteed price for exported power) or selling on the spot market (the short-term wholesale market) is considered. Additional economic scenarios are also tested for PVBES to improve viability. Results show that under the same assumptions, the PV+diesel (PVDG) system is the most favorable economically, even though all three systems have negative NPV. However, the PV+battery (PVBES) configuration offers greater flexibility and access to extra revenue on the balancing market or through power purchase agreements (PPAs). With these options included, PVBES becomes the best economic choice and achieves a payback time of 8–16 years. In addition, operating the PVBES system causes no CO2 emissions.
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