Abstract
The planning of the energy transition from fossil fuels to renewables requires estimates for how much electricity wind turbines can generate from the prevailing atmospheric conditions. Here, we estimate monthly ideal wind energy generation from datasets of wind speeds, air density and installed wind turbines in Germany and compare these to reported actual yields. Both yields were used in a statistical model to identify and quantify factors that reduced actual compared to ideal yields. The installed capacity within the region had no significant influence. Turbine age and park size resulted in significant yield reductions. Predicted yields increased from 9.1 TWh/a in 2000 to 58.9 TWh/a in 2014 resulting from an increase in installed capacity from 5.7 GW to 37.6 GW, which agrees very well with reported estimates for Germany. The age effect, which includes turbine aging and possibly other external effects, lowered yields from 3.6 to 6.7% from 2000 to 2014. The effect of park size decreased annual yields by 1.9% throughout this period. However, actual monthly yields represent on average only 73.7% of the ideal yields, with unknown causes. We conclude that the combination of ideal yields predicted from wind conditions with observed yields is suitable to derive realistic estimates of wind energy generation as well as realistic resource potentials.
Highlights
With the Energiewende or energy transition from fossil fuels to renewables, wind energy became a mainstream energy source [1]
We used the ideal wind energy yield and actual monthly energy yields of a subset of wind turbines to set up a mixed-effects model that we applied to all wind turbines in Germany to estimate the actual monthly energy yield
Only 73.7±0.2% of the ideal wind energy yield was converted to electrical energy
Summary
With the Energiewende or energy transition from fossil fuels to renewables, wind energy became a mainstream energy source [1]. It was the second largest renewable energy source after hydropower in 2015 with a total installed capacity of 433 GW globally [2]. According to the EU Energy Roadmap 2050, apart from energy conservation the switch to renewable energy sources is the second major prerequisite for a more sustainable energy system [3]. In 2016, renewable energy sources had a share of 32% of total electrical energy production in Germany with wind energy contributing about a third to this share [4]. The German legislation plans to further extend renewable energy and sets the target to generate 80% of electrical energy from
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