Chapter 10 - Meteorological assessment of coupled wind–solar power generation regimes in Spain

Abstract

Wind and solar power generation exhibit variability over a wide range of time scales. This intermittency is probably the most important drawback in terms of increasing the participation of these energies in the power systems. A proper distribution of wind and solar plants in a region has been reported to be a successful way to reduce the fluctuations in the aggregated-power supply. This reduction is enhanced when the allocation of the renewable power capacity makes use of the spatiotemporal variability of the wind and solar energy resources. Indeed, by exploiting the spatial and temporal complementarity of the wind and solar energy resources, below-normal power generation in some areas can be balanced with above-normal generation in other areas at given times, thereby reducing the fluctuations in the power generation. The main objective of this study is to assess the extent to which the wind and solar power generation is coupled in Spain on daily time scales, as well as to analyze their associated weather patterns. A byproduct of this study is the identification of coupled wind–solar power generation modes exhibiting balancing. To this end, gridded daily solar and wind power generation time series, spanning a period of 10 years (2001–10) and covering Spain, are used as input of a clustering algorithm. As a result, coupled power regimes (CPRs) are obtained. For each of these CPRs, the spatial distribution of the wind and solar power generation and the associated synoptic weather patterns are evaluated. The CPRs are interpreted on the light of these weather patterns and the topographic features of the study region. The results reveal the existence of six-coupled modes for winter and four for the rest of the seasons, with only some of these modes being relevant regarding the balancing between the wind and solar power generation. A marked seasonality of the balancing strength as well as their spatial and temporal covering is observed. The most relevant balancing is detected during autumn, followed by winter, spring, and, lastly, summer. It is found that all the balancing modes, except the summer ones, are associated with the presence of a positive/negative (alternating) center of pressures anomalies located, roughly, over Ireland. The interaction of the resulting wind circulation with the existing topographical features explains the balancing patterns. The results reported in this study may have important consequences regarding the optimal spatial allocation of new renewable power plants over Spain. Nevertheless, the practical usefulness of the results implies the use of some daily energy storage system.