Optimal capacity expansion pathway of renewable energy and energy storage under 2050 net-zero in South Korea

Abstract

Renewable energy is being presented as a sustainable solution to the problems raised by the climate crisis. Accordingly, the Korean government is also considering renewable energy and nuclear power as means of achieving carbon neutrality in the power sector. However, due to the output fluctuation and intermittency of renewable energy, Energy Storage System (ESS) is required. The ESS device stores surplus power as other types of energy and discharges it back into the grid during high load times to relieve power supply instability caused by renewable energy. However, unlike renewable energy, where detailed capacity expansion plans are continuously established, specific plans for energy storage devices are being delayed. Accordingly, the capacity expansion planning model is employed to emphasize the need for the simultaneous planning of renewable energy and energy storage devices and compare the cost and the amount of device capacity required to achieve carbon neutrality and the total curtailment with the result of individual planning. In addition, ESS as a facility that is still not commercialized as renewable energy technology, the uncertainty of the cost prediction exists. Therefore, the impact of cost reduction speed - which represents technology development – on the result is also investigated. The result shows that co-optimization reduced the amount of renewable energy facility required to achieve carbon neutrality by 2050, and also reduced the total cost for capacity expansion and operation. In addition, it was shown that the curtailment of renewable energy was greatly reduced, in other words, the operational efficiency of renewable energy in carbon neutrality was also improved. Meanwhile, the acceleration in the speed of ESS technology development creates a synergy that primarily induces an increase in the size of ESS, furthermore, decreased the demand for renewable energy capacity. Consequently, the total cost diminished. Besides, the curtailment is also mitigated with the acceleration of cost reduction speed. This study emphasizes the need for co-optimization planning of renewable energy and ESS facilities to Korean policymakers, and at the same time helps them understand the changes that might take place when the technology development rate of energy storage varies. In addition, unlike previous studies, the time resolution of facility operation was set to one hour to describe the volatility of renewable energy output and the charging and discharging decisions of ESS in more detail. Thus, the result of capacity expansion planning could reflect a more realistic quantity demand for the facilities.