Assessment of the Economic Efficiency of Battery Energy Storage Systems in the Electricity Market Segments

The actuality of introducing electricity storage facilities in the IPS of Ukraine is due, in particular, to the increasing share of non-guaranteed capacity power plants, namely wind and solar power plants, in the structure of electricity production, which requires increasing the flexibility of the power system. However, there are currently practically no pilot projects that would serve as an indicator for the implementation of new investment BESS projects. In view of this, it is relevant to conduct a study of the economic efficiency of electricity storage in different segments of the electricity market in Ukraine, taking into account the current price indicators for the purchase and sale of electricity on the day-ahead market and the cost of providing ancillary services. The article investigates the economic efficiency of a two-hourly BESS with a nominal power of 2 MW and a commercial energy capacity of 4 MWh, which provides a symmetrical frequency support reserve service in the ancillary services market, or operates in the energy arbitrage mode, i.e., purchases electricity at the lowest price period and sells it at the highest price period in the day-ahead market in the IPS of Ukraine. The study found that the current difference between the purchase price of electricity during periods of minimum prices and the sale price during periods of maximum prices on the day-ahead market in the IPS of Ukraine does not provide a sufficient level of profitability, even taking into account the forecast annual growth of 4.61% in market prices and the implementation of two complete cycles of charging and discharging batteries during each day of the year. In the current price conditions, the most profitable BESS projects are those used to provide ancillary services for frequency and active power regulation, namely symmetrical frequency support reserve, with a discounted payback period of 6–7 years.