Impact of Climate Change on Dark Doldrums (Dunkelflaute) and Extremely High Residual Load in Japan

　So-called “Dark Doldrums (i.e., Dunkelflaute or variable renewable energy [VRE] drought),” in which periods of “no light, no wind” last for several days, constitute a risk of long-term power supply disruptions when VRE sources such as wind and solar power have high penetration rates. Previous studies (Ohba et al. 2021; 2022) have shed light on the frequency and meteorological/climatological factors of dark doldrums for historical weather conditions. However, it has been noted that wind and solar output and electricity demand will change due to climate change (Ohba 2019). Thus, there is concern that the occurrence of Dark Doldrums and its impact on supply capacity shortages will change in the future. In this study, the impact of climate change on the occurrence of Dark Doldrums in Japan was assessed using large ensemble regional climate projections derived from the database for Policy Decision making for Future climate change (d4PDF). Using a machine learning model, hourly electricity demand and solar and wind power generation were projected for 732 years each under historical climate and future climate conditions with 2K and 4K temperature warming, respectively. The results showed that the frequency of Dark Doldrums tends to increase under the influence of climate change. Daily maximum electricity demand also tended to increase with rising temperatures, suggesting the possibility of unprecedented long-term high residual demand events.

 

REFERENCES

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• Ohba M, Kanno Y, Nohara D. Climatology of dark doldrums in Japan, Renewable and Sustainable Energy Reviews 155 (2022) 111927.
• Ohba M. The Impact of Global Warming on Wind Energy Resources and Ramp Events in Japan. Atmosphere, 10 (2019) 265