Capacity Value of Pumped-Hydro Energy Storage

This paper presents an estimation of the contribution of pumped-hydro energy storage (PHES) stations to capacity adequacy. To assess the capacity value of the PHES, a Monte Carlo simulation model is developed and the Equivalent Firm Capacity metric is utilized. Several PHES configurations are examined in terms of rated power and energy capacity, using the Greek power system as a study case. The impact of several key parameters on the capacity value of PHES is investigated through a sensitivity analysis, including the roundtrip efficiency and the reliability of the plant, reliability parameters of the thermal units, and the level of variable renewables in the system in terms of installed capacity and mix of technologies. One of the main findings of this work is that PHES stations of at least 6-h energy to power ratio and an aggregate capacity of up to 2000 MW present a capacity value in excess of 75%. The PHES capacity value is strongly dependent on the penetration of solar photovoltaics in the energy mix, while it is relatively uncorrelated to the level of wind power integrated into the system.