US Wind Turbine Technology Trends in 2017: Part 2

The Department of Energy recently published its 2017 edition of the annual Wind Technologies Market Report. It is a perennial wealth of data and worth sharing its key highlights. The report is a perennial trove of data; I have split its key highlights into a three-part blog series. The first focused on broader installation, market, and industry trends. This second blog focuses on wind turbine and wind plant technology and performance trends. The third and final blog in this series will focus on turbine cost and wind power price trends. 

Part 2: Technology and Performance Trends 

Technology Trends

Average turbine capacity, rotor diameter, and hub height increased in 2017, continuing the long-term trend. To optimize wind power project cost and performance, turbines continues to grow in size. The average rated (nameplate) capacity of newly installed wind turbines in the US in 2017 was 2.32 MW, up 8% from the previous year. The average rotor diameter in 2017 was 113 meters, a 4% increase over the previous year. The average hub height in 2017 was 86 meters, up 4% over the previous year. 

Turbines originally designed for lower wind speed sites have rapidly gained market share and are being deployed in a range of wind resource conditions. In 2017, the majority of new installations used International Electrotechnical Commission (IEC) Class III and Class II/III turbines—turbines specifically certified for lower wind speed sites. Turbines designed for these lower wind speeds continue to be deployed in both lower and higher wind speed sites. IEC Class III and II/III turbines continue to be employed in all regions of the US.

Meanwhile, the tallest towers continue to be deployed in the Great Lakes and Northeastern regions, in lower wind speed sites. The specific location decisions are likely driven by the wind profile at the site. Wind power projects planned for the near future continue the trend of ever-taller turbines. 

Numerous wind power projects continued to employ multiple turbine configurations from a single turbine supplier. Nearly a quarter of the larger wind power projects built in 2016 and 2017 used turbines with multiple hub heights, rotor diameters, and/or capacities—all supplied by the same OEM. This development may reflect increasing sophistication due to turbine siting and wake effects, coupled with an increasing willingness among turbine suppliers to provide multiple turbine configurations, leading to increased site optimization. In its Capturing and Maximizing Wind Power Plant Data report, Guidehouse Insights investigated similar optimization efforts via data collection strategies at wind plants. Keep an eye out for its upcoming report on wind turbine optimization services. 

Performance Trends

Sample-wide capacity factors have gradually increased but have been influenced by curtailment and inter-year wind resource variability. Wind project performance has generally increased over time, driven largely by turbine scaling. However, inter-year variations in the strength of the wind resource and changes in the amount of wind energy curtailment have partially masked the influence of turbine scaling on wind project performance. On average, wind speeds were near-normal compared to earlier years across the US and for 2017, while wind energy curtailment remained modest at around 2.5%.

Turbine design changes are driving capacity factors significantly higher among projects located in given wind resource regimes. Focusing on performance solely in 2017 helps identify underlying trends. The average 2017 capacity factor among projects built from 2014 to 2016 was 42.0%, compared to an average of 31.5% among projects built from 2004 to 2011 and just 23.5% among projects built from 1998 to 2001. Older projects, meanwhile, appear to suffer from performance degradation, particularly in their second decade of operations.