Estimation of the correlation of offshore wind power generation across Japan

This report presents a study on offshore wind generation in Japan with focus on how deployment over a large geographical area can decrease the variability in the aggregate offshore wind generation. Using the Correlations in Renewable Energy Sources (CorRES) tool, the likelihoods of very low and high wind generation hours during a 41-year simulation period and how they are impacted by the spatial placement of wind power plants is presented. The investigation of estimating the correlation of wind generation across Japan shows that the overall variability is significantly reduced when installations are geographically highly spread. Standard deviation of standardized offshore wind generation is reduced by 40 percent, and likelihoods of very low or very high generation hours are reduced. The 1-hour ramp variability, i.e., the tendency of aggregate wind generation to change significantly within one hour, is reduced by 65 percent, indicating a lower impact on the rest of the energy system in terms of 1-hour flexibility requirements. The lower aggregate variability obtained via geographical smoothing shows that highly spread installations are expected to reduce the system integration challenges when increasing offshore wind installations in Japan