Battery Energy Storage Systems as an alternative to gas turbines for the fast active disturbance reserve

Abstract: Power systems operate at a specific frequency and constantly require a balance between production and consumption of electricity in order to maintain the frequency within a certain interval. Larger frequency deviations can cause blackouts or damage equipment connected to the grid. Balancing functions that stabilise the grid are referred to as \textit{ancillary services}, which in Sweden include the fast active disturbance reserve (FADR) that currently consists of a fleet of gas turbines. Svenska Kraftnät Gasturbiner (SvkGT) is a subsidiary company to the Swedish Transmission System Operator (TSO), responsible for the operation of a number of these turbines devoted for FADR use. With an increasing amount of non-continuous, \textit{intermittent energy sources} in the energy mix, the demand for ancillary services keep increasing. To achieve the Swedish national goal of zero net emissions by 2045, it is of utmost importance to evaluate potential technologies that could provide FADR services in a more environmentally sustainable way or consider using intermittent production for balancing means. Utility scale battery energy storage systems (BESS) have lately been introduced in different parts of the world as an enabler to store intermittent energy which can be used when needed. The deployment of BESS has been drastic over the last few years, but the technology has yet to be introduced in Sweden. This report aims to evaluate BESS and the technology’s potential as a complement or substitution to current gas turbines devoted for FADR use. This report compares BESS to gas turbines through a cost-benefit analysis focused on FADR use. Initially, a requirement specification for the FADR is established based on regulations and operational data of current turbines. Three different battery technologies are evaluated through a literature study and combined with a case study of the 100 largest BESS facilities in the world. Additional interviews with a variety of battery suppliers have also been conducted. The results indicate that the Li-ion technology currently dominates the BESS market and that the most common area of application is for primary reserves such as fast frequency regulation (FFR). FFR is considered the optimal application for batteries, mainly due to their unique ability to supply power quickly. The results also establish that all battery technologies are technically capable of meeting most of the criteria for FADR use, but practically fail to achieve the criteria of “Electricity readiness”, stating that a 100-hour duration of power supply is essential for the FADR. However, the results from the operational statistics for the current FADR conclude that a battery could stay competitive to a gas turbine from a cost perspective while covering up to 97\% of the FADR demand. Finally it is concluded that the Vanadium Redox Flow battery is the technology that show greatest potential for FADR use, mainly due to its low price, high robustness, low degradation rate and the fact that its poor round-trip efficiency is of smaller concern when the asset is intended for FADR operation. Additionally, projections of performance improvements for batteries, combined with a continuation of declining prices, indicate that batteries will be real game changers for ancillary services in the future.