Optimization of hybrid off-grid system consisting of renewables and Li-ion batteries

Abstract

The capacities of the wind turbines, solar photovoltaic (PV) panels, and lithium-ion (Li-ion) batteries composing an off-grid system are optimized. The model of the Li-ion batteries considers the capacity fading and temperature variation. A case study on Jeju Island demonstrates the capacity factors of the onshore and offshore wind energy, and solar PV energy. The optimal capacities of the onshore and offshore wind turbines, solar PV panels, and Li-ion batteries are evaluated as 16 MW, 1532 MW, 6076 MW, and 14,651 MWh, respectively, without capacity fading. The corresponding life cycle cost (LCC) and levelized cost of electricity (LCOE) are evaluated as 84.3 BUSD and 0.42 USD kWh−1, respectively. With capacity fading, the optimal capacities of the onshore and offshore wind turbines, solar PV panels, and Li-ion batteries are estimated as 2 MW, 1947 MW, 5072 MW, and 16,927 MWh, respectively. The corresponding LCC and LCOE are nearly invariant. The maximum temperature of the Li-ion batteries is estimated for different cooling conditions. The convection coefficients are suggested for negligible performance degradation and preventing thermal runaway. Finally, sensitivity analysis is conducted for different renewables penetrations, the portion of electric vehicles (EVs), and demand reduction during summer.