New study explores the hidden value of large-rotor, tall-tower wind turbines

July 6, 2020

Supersized wind turbines could deliver $4-5/MWh more in grid benefits than today’s turbine technology, in addition to any direct-cost advantages

Study supports need to expand the design space to focus not only on direct-cost minimization, but also on the underlying value of wind to the electricity system

new study by Berkeley Lab, published in the journal Wind Engineering, shows that supersized wind turbines can enhance the value of wind energy to the electricity system and provide other ‘hidden’ benefits. These benefits are in addition to the reduction in levelized costs that such turbines may provide, and illustrate the importance of expanding wind turbine design to focus not only on direct-cost minimization, but also on a broader set of factors that impact the value of wind to the electricity grid.

The significant increases in wind turbine size (nameplate capacity, rotor diameter, and tower height) in recent years have, to date, been driven primarily by a goal of minimizing the levelized cost of wind energy (LCOE). Previous research by Berkeley Lab suggests that even larger ‘supersized’ turbines—featuring larger rotor swept areas relative to nameplate capacity, and taller towers—might enable further LCOE reduction of ~$6/MWh. Other research by DNV GL identified a number of potential solutions to the logistical challenges associated with deploying supersized turbines. But with wind’s LCOE now comparable to that of other generating resources, other design considerations besides cost-minimization have grown in importance—particularly as wind penetration increasingly impacts the electricity grid and reduces wind’s marginal value to the grid. The newly released paper addresses that expanded design need, analyzing the impact of large wind turbines on grid-system value. 

The study’s results demonstrate a possible double dividend: that larger rotors (relative to nameplate capacity) and taller towers might not only reduce LCOE, but could also enhance the value of wind energy and provide other heretofore ‘hidden’ benefits. These benefits largely come from the increased capacity factors that larger rotors and taller towers enable, and the fact that such supersized turbines tend to spread wind output proportionately over more hours of the year.

Specifically, the analysis leverages recent hourly wholesale pricing patterns and hourly wind profiles for wind plants located in the seven organized wholesale markets (i.e., ISOs) in the United States. The study finds that in regions where wind penetration has reached around 20% (such as ERCOT and SPP), supersized turbines could already boost wholesale energy and capacity value by $2-3/MWh on average, compared to turbines deployed in the recent past (Figure 1). Across all ISO regions, the average value boost is $1-2/MWh; for specific plants, the value enhancement is already as much as ~$5/MWh.

These wholesale market value benefits are augmented by three additional possible advantages of up-scaled turbines: reduced transmission expenditure due to greater transmission utilization, lower balancing costs for the electricity system due to lower aggregate wind output variability, and lower financing costs due to less long-term wind output uncertainty. The analysis finds that these three benefits sum to roughly $2/MWh (Figure 2), adding to the $2-3/MWh energy and capacity value boost seen in regions with higher wind penetrations (Figure 1). 

Considering all of the benefits analyzed, the aggregate benefit averages $4-5/MWh in higher wind-penetration areas. Moreover, these possible benefits add to the $6/MWh of potential LCOE advantage of supersized turbines assessed in earlier work, yielding total benefits of ~$10/MWh. The degree to which these advantages are ultimately realized, and at what point turbine size plateaus, will be determined by future wholesale price patterns, the success of continued design and materials optimization, social acceptance and regulatory hurdles, and the logistical constraints of transporting and erecting even-larger blades, towers, and nacelle components.

 

Wind energy has deployed rapidly on a global basis, but continued technical advancements will be necessary if wind energy is to reach its full potential. This paper contributes to a growing understanding of one innovation pathway—further upscaling in turbine size—by focusing on several less-recognized benefits of larger-rotor and taller-tower land-based wind turbines. More generally, the analysis also illustrates the growing importance of factors beyond plant-level costs in turbine and project design and operations. As wind penetrations increase, the output profile and characteristics of wind begin to impose challenges to the electric grid. By expanding the analysis scope to consider supplementary factors that influence the system economics of wind—market value, transmission, balancing, and financing—turbine designers, project developers, and wind R&D experts can help ensure that wind plants of the future seek a balance between minimizing costs and maximizing value.

The new journal article (along with a PowerPoint summary), titled “The Hidden Value of Large-Rotor, Tall-Tower Wind Turbines in the United States” can be accessed here. The previous article on which the present work builds can be found here.

This work was funded by the U.S. Department of Energy’s Wind Energy Technologies Office. The views expressed here do not necessarily represent the views of the U.S. Department of Energy or the U.S. Government.

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