Komiyama, Ryoichi, and Yasumasa Fujii

Abstract
This paper comprehensively analyzes an optimal deployment of variable renewables (VRs) with flexible power resources, such as electricity saving and rechargeable battery, in Japan’s long-term power generation mix to 2050 under possible nuclear energy scenarios. The study is performed, employing a dynamic high time-resolution optimal power generation mix model which is formulated as a large-scale linear programming model. Simulation results show that both complete nuclear phase-out and carbon reduction by 80% in 2050 from 2010 encourage VR expansion in the country’s power system and cause a quadruple increase of power generation cost at 2050 compared with that under current nuclear capacity and no carbon regulation policy; long-term cost reduction of VR energy system is necessary if VR is positioned as a mainstream for future sustainable power supply. Secondly, higher levels of VR integration decrease the capacity factor of LNG combined cycle (LNGCC), which implies the challenge to assure LNGCC serving as a remunerated ramp generator for VR intermittency. Finally, as an economically optimal solution, electricity saving serves as an important option to integrate massive VR and to treat a seasonal imbalance of its power output in an efficient way.
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