Estimating energy storage size for Nuclear-Renewable hybrid energy systems using data-driven stochastic emulators

The increased electricity production from renewable energy sources, such as wind, in recent years has contributed to an increase in grid variability. This creates the need for clean, reliable, and flexible back-up electricity generation to complement the renewables and match the grid demand. Nuclear power is a clean, reliable energy source for back-up energy generation but cannot be operated in a manner flexible enough to compensate for the high uncertainties in renewable energy production. To maintain the grid stability with clean energy production and limited operational flexibility of nuclear power, appropriately sized energy storage solutions are needed. Typically, such integrated energy systems are modeled using deterministic methods which are not suitable to accommodate fluctuating energy production and safety constraints on nuclear power plants. This work developed a continuous-time stochastic model for integrating wind and nuclear power with energy storage. The model was then demonstrated for an isolated microgrid using the yearly demand and wind generation data, with nuclear and wind energy as the only power generation sources. Multiple scenarios were analyzed with varying wind penetrations and nuclear flexibility limitations, and the energy storage sizes and their utilization fractions were calculated for three different energy storage types. Without the implementation of energy storage, the required nuclear power capacity should be above the average grid load, and most of the wind power is wasted. By implementing energy storage and using nuclear as a constant base-load, the wind power can account for a larger fraction of the grid, however the storage size requirements are large and utilization fractions are small. If the nuclear power is allowed to operate with greater flexibility than current ramp rate limitations, the storage requirement decreases and storage utilization increases. Of the three storage types analyzed, thermal storage is found to be lowest in size requirement with the highest utilization factors for all scenarios.