Demand-side flexibility in shopping centres - a case study on Väla shopping centre

Abstract: Sweden is heading towards an energy system with less nuclear power and more intermittent energy sources. Together with the coming electrification of the transport and industry sector, this challenges the future stability of the Swedish power system. However, a part of the solution could be that consumption of electricity temporarily is adjusted to facilitate the operation of the power system, recognized as Demand-Side Flexibility (DSF). The purpose of this thesis has been to investigate the prerequisites for Väla shopping centre to offer DSF with strategic load control and operation of a Battery Energy Storage System (BESS). A technical assessment of loads has been carried out using four important characteristics of consumer flexibility: sheddability, controllability, availability and acceptability. The ventilation system, comfort cooling system and indoor lightning were qualitatively evaluated using these flexibility parameters. In the BESS assessment, simulations of peak power reduction were conducted using a software System Advisor Model. The technical potential was evaluated for two BESS dimensions and was translated into savings using grid fee agreements from both Öresundskraft and E.ON. This analysis was complemented with a qualitative analysis of the prerequisites to also use the BESS for frequency regulation. The results show that DSF with loads at Väla shopping centre constitutes a complex technical challenge, since existing control chains and systems would have to be retrofitted to serve new purposes. It was concluded that the ventilation system was best suited for DSF applications out of the three investigated loads. The reasons for this were the presence of controllable variable frequency drives, the predictable availability pattern with respect to operating power and the large installed nominal capacity. The BESS simulations show that yearly peak power demand potentially could be reduced by 12-14% with BESS dimensions of 1600 kW/2000 kWh and 1200kW/1500 kWh. These BESS dimensions would generate average yearly savings of 333-284 TSEK with E.ON’s grid fee and 198-178 TSEK with Öresundskraft’s grid fee. The calculation of Pay-Back Time (PBT) and Net Present Value (NPV) indicate that E.ON’s grid fee and the smaller BESS would be more economically favorable, but that an investment in a BESS would not be profitable, neither with the current circumstances nor with a future lower BESS price. The base case indicates that the PBT of the investigated BESS dimensions lies between 33-63 years. In a hypothetical scenario with a future lower BESS price and significant price development of power components in the grid fee, the PBT becomes 10-12 years. From the analysis of the prerequisites for providing frequency control, it was concluded that the BESS legislatively could be qualified as a balancing resource on the reserve market. Furthermore, the operational performance analysis indicated that the BESS would be available for frequency regulation during longer periods of time even if reducing peak power would be prioritized throughout the year. The main limitation for providing frequency control is the risk of increasing the yearly costs towards the network operator during a down-regulation at times when the power demand at Väla shopping centre is close to its cost determinative power level.