Reasons for the Recent Onshore Wind Capacity Factor Increase

Increasing wind capacity and capacity factors (CF) are essential for achieving the goals set by the Paris Climate Agreement. From 2010-2012 to 2018-2020, the 3-year mean CF of the global onshore wind turbine fleet rose from 0.22 to 0.25. Wind turbine siting, wind turbine technology, hub height, and curtailed wind energy are well-known CF drivers. However, the extent of these drivers for CF is unknown. Thus, the goal is to quantify the shares of the four drivers in CF development in Germany as a case. Newly developed national power curves from high-resolution wind speed models and hourly energy market data are the basis for the study. We created four scenarios, each with one driver kept constant at the 2010-2012 level, in order to quantify the share of a driver for CF change between 2010-2012 and 2019-2021. The results indicated that rising hub heights increased CF by 10.4%. Improved wind turbine technology caused 7.3% higher CF. However, the absolute CF increase amounted to only 11.9%. It is because less favorable wind turbine sites and curtailment in the later period moderated the CF increase by 2.1% and 3.6%, respectively. The drivers are mainly responsible for perennial CF development. In contrast, variations in wind resource availability drive the enormous CF inter-annual variability. No multi-year wind resource change was detected.

Automated summary

Based on the study of Germany as a case, turbine site selection, turbine technology, hub height, and curtailed wind energy are the main drivers for wind capacity and capacity factor development. Specifically, increasing hub heights and improved turbine technology resulted in 10.4% and 7.3% higher capacity factors, respectively.