Utility-scale photovoltaic & battery storage systems - Techno-economic feasibility study of the new stadium in Freiburg, Germany

Abstract

The highest amount of CO2 emissions in the European Union is caused by the energy sector. The growing problems due to climate change and thus the need for a decarbonisation of the energy sector has pushed the implementation of renewable energy technologies on a global scale. With the increasing amount of renewable energy technologies new challenges arise, especially concerning the fluctuating availability of produced electricity. One solution to this challenge is to add a battery storage to the renewable energy plant, however, these storage units are associated with high investment costs especially in the utility scale, and are therefore often not taken into consideration. In order to bring forward the implementation of renewable energy technologies among large consumers, the techno-economic feasibility of a utility-scale solar power plant in combination with a utility-scale battery storage is assessed. This is done through a case study of the new football stadium in Freiburg, Germany. The current practice is to cover the stadium's load with a diesel generator during match, while the remaining base load is powered by electricity from the grid. By investing into a rooftop photovoltaic plant with a battery storage as an alternative, the stadium does not only replace the diesel unit but also provides itself with a system which can create revenues. Given the high capacity requirement of the battery to power a game event and match only occurring 18 times a year, the battery can be used for electricity storage and trade in the remaining time. In order to assess the feasibility of this system, the load profile of the stadium is identified. Then, three different systems are modelled with the software energyPRO. The first system represents the current practice with the diesel generator (DG system). The second system adds a photovoltaic plant to the first system with the diesel generator (PVDG system). The third system consists of the photovoltaic plant and the utility-scale battery storage with no diesel unit (PVBES system). The assessment is carried out by first identifying the technical performance of the different systems. Then, the relevant investment and operational costs for the different systems are determined. Further expenses like electricity purchase from the grid but also the relevant surcharges, taxes and fees are identified. Taking all the cash flows into account, the economic feasibility is assessed by calculating the net present value of the systems, with consideration of receiving a feed-in tariff or trading electricity on the spot market with the PVDG and the PVBES system. Furthermore, different economic scenarios are considered for the PVBES system in order to improve the economic feasibility. The results show that under the same conditions, the PVDG system offers the economically most favourable solution, despite the net present value of all systems being negative. Nevertheless, the PVBES system offers more flexibility and allows the stadium operator to consider other revenue options on the balancing market or through power purchase agreements. With these options considered, the PVBES system not only offers the economically best option, but also pays off the expenses with a payback-time between 8 and 16 years. In addition, no CO2 emissions occur through the operation of the PVBES system.

A master thesis from Aalborg University

Utility-scale photovoltaic & battery storage systems - Techno-economic feasibility study of the new stadium in Freiburg, Germany