Abstract
The authors’ previous assessment indicated that the marginal electricity cost in 2050 in Japan is more than doubled in an energy system based on a 100% renewable power supply compared to the cost-optimal system. However, some assumptions may be conservative given the recent developments, including the cost of variable renewable energy (VRE) and energy storage technologies and the availability of dispatchable renewable power generation (such as biomass-fired). Therefore, to test the robustness of the previous assessment, this study conducts a sensitivity analysis with a focus on these factors, using an energy system optimization model with a detailed temporal resolution. Simulation results imply that the high marginal electricity cost in the “100% renewable power system” is partially due to the costs of managing VRE’s seasonality. Low-cost energy storage and dispatchable renewable power plants can curb the marginal electricity cost. However, the results also suggest that the marginal cost in these sensitivity cases remains high compared to the cost-optimal system, still posing economic challenges to the system based on a 100% renewable power supply.
