Dampening variation in the European Wind Energy System

Licentiate thesis, 2015

In a future European electricity system, wind power and other variable renewables may constitute a large share of electricity production. This prospect calls for measures to manage the inherent variability of wind power, such as demand-side management, storage, and flexibility of other generation. Another way of managing variation is to take advantage of the weather patterns when allocating wind power over larger areas, so that the aggregated output of wind power displays lower variation than that of a single region. The extent to which aggregated wind variations can be managed depends on geographic scope and the limitations in transmission capacity between regions. Of great importance is the extent to which the aggregated wind power output can be smoothened through geographic allocation. Therefore, this thesis explores the limits of geographic smoothing, by optimizing the regional allocation of wind power in Europe. This thesis first provides a description of the variability of geographically dispersed aggregated wind power, using a heuristic method to identify allocations with minimum variability while maintaining a high average output. The region in focus encompasses the Nordic countries and Germany. Then, the features of aggregated wind power that can provide system benefits are identified, and the optimal allocations of wind power capacity are explored with Europe as the geographic region. System benefits are formulated as objectives in optimization models, and the trade-offs between these benefits are analyzed. Allocations that yield the following system benefits are investigated: - A high average output - A smooth output, in which increments within the time-span of 3–24 hours have been minimized - An output that avoids low output - An output in which wind power covers the maximum load within the region where it is produced. The only one of the system benefits that is explicitly in favor of windy spots is the one of high average output. However, the results presented in this thesis show that the allocations that result from optimizing the other system benefits tend to display a high capacity factor, of around 30%, given the assumptions applied. This should be compared to the highest possible capacity factor obtained (34%). Thus, considering that the present allocation has a capacity factor of 20%, there are potentially large benefits to be gained from optimizing geographic allocation. Furthermore, it is shown that avoiding low output and smoothing the output give rise to similar allocations, i.e., there is virtually no trade-off between these two goals. The objective of covering maximum load results in an allocation with high penetration levels of wind power, up to 60% of annual load, in windy regions. Taken together, the results presented in this thesis highlight that wind power allocation can contribute to efficient use of wind power in a future Europe with a high share of variable renewables in the electricity system.