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Wind Power Project Repowering: 

History, Economics, and Demand

Wind Exchange Webinar

Eric Lantz

January 21, 2015

NREL/PR-6A20-63591
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Presentation Overview

1. Background – Concepts and Context

2. Status – U.S. and Globally 

3. Economics – Conceptual and ‘Actual’ Plants

4. Future Demand – Expectations for the 2020s

5. Key Takeaways – Summary of Findings
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Background

• Repowering can be defined in two ways:

o Full repowering: complete dismantling and replacement of turbine 

equipment at an existing project site

o Partial repowering: replacing selected turbine or plant components to 

extend the life of a given facility at some cost that is less than full 

repowering; may also trigger fewer legal hurdles

• Repowering offers various opportunities:

o Increased project productivity 

o Improved grid support and interactions

o Better utilization of high-value resource areas 

o Reduced visual impacts (fewer turbines per overall capacity)

o Potentially, reduced avian and wildlife impacts

• Repowering first emerged in the early 1990s in the California and 

Danish wind power markets and was followed by the Dutch and 

German markets in the 1990s and 2000s
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Status

• Denmark: 

o Typically repowers 10s to 100s of MW per year

o Has historically provided repowering incentives that are in addition to feed-in-tariffs

o Cited constraints include: capital requirements of new projects, shifts in ownership 

models away from the community, limited economic value

• Germany:

o Observed to have the largest potential market for repowering, estimated at 

approximately 6 GW

o Typically repowers 10s to 100s of MW per year

o Has historically provided repowering incentives that are in addition to feed-in-tariffs

o Cited constraints include setbacks, turbine height restrictions, and limited economic 

value

• U.S.

o 1980s and 1990s vintage technology in California represents the primary current 

opportunity for repowering in the U.S. (~2 GW), but has been limited by the 

‘California Fix’ among other policy and regulatory factors

• To date, repowering has tended to be Full Repowering
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Economics: Phase 1 Analysis

• Develop representative plants for four specific points in time: 1999, 2003, 2008, 2012

• Quantify and compare the financial impacts of Full Repowering and Developing an Adjacent Greenfield Site

• Quantify and compare the financial impacts of Partial Repowering, Full Repowering and Developing an Adjacent 

Greenfield Site, for the 2003 conceptual plant in 2025

Conceptual Plant Technology, Cost, and Performance Parameters

Source: Lantz et al., 2013
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Economics: Conceptual Plants

1999 2003

Source: Lantz et al., 2013; Note: data illustrate value gained or lost as a result of a specific investment decision; as each of these plants is modeled at an equivalent 

size, the change in plant-specific NPVs can be compared across time; however, caution is advised against any direct assessment of wind plant profitability or return on 

investment, as the overall magnitude of NPV is highly correlated to plant size

• Wind power plants built in 1999 appear to be reasonably profitable after about 15 years of 

operations, but both repowering and developing an adjacent greenfield could add additional 

value

• After 20 years, the economics start to shift, with full repowering becoming more attractive than 

an adjacent greenfield sometime between 20 and 25 years of operation

• For the 2003 facility, analysis suggests that building an adjacent greenfield plant in 2015 and 2020 

is also the preferred alternative; however, repowering appears to become financially attractive a 

bit sooner, between 16 and 21 years of operation (2020–2025) 

• The shorter expected lifetime for the 2003 facility is a function of its lower estimated PPA price, 

which results in lower overall profitability and allows increasing operational costs to erode the 

value of these projects, earlier in their life
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Economics: Conceptual Plants

• Full repowering results in a reduction in the NPV of future after-tax cash flows, 

through 2030, for these more recent projects

• This effect is in part the result of historically high PPAs signed in 2008, but also 

results from the assumed declines in pricing that are expected as future 

technology advancements and cost reductions are realized

• Based on these results, more recent projects could ultimately delay repowering 

investments until 25 years of operation or beyond

2008 2012

Source: Lantz et al., 2013; Note: data illustrate value gained or lost as a result of a specific investment decision; as each of these plants is modeled at an equivalent 

size, the change in plant-specific NPVs can be compared across time; however, caution is advised against any direct assessment of wind plant profitability or return on 

investment, as the overall magnitude of NPV is highly correlated to plant size
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Economics: Partial Repowering 2003 Plant

• Analysis of partial repowering 

assumes:

o Replacement of rotor and drivetrain

o Increase in NCF from 30% to 37%

o 15% cost reduction relative to a green 

field (~10% relative to repowering)

o Construction in 2025 

• From these premises, the benefits of 

partial repowering come in well 

below that of developing an adjacent 

greenfield and full repowering

• Partial repowering solutions that can 

be realized at lower cost, would likely 

prove more viable

Source: Lantz et al., 2013; Note: data illustrate value gained or lost as a result of a specific 

investment decision; as each of these plants is modeled at an equivalent size, the change in 

plant-specific NPVs can be compared across time; however, caution is advised against any 

direct assessment of wind plant profitability or return on investment, as the overall magnitude 

of NPV is highly correlated to plant size
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Economics: Case Study Analysis

Source: Lantz et al., 2013; Note: Comparing the NPV across the three case studies is not appropriate. 

The absolute magnitude of the NPV is highly correlated with the size of the wind plant, as larger 

wind plants require higher levels of investment. Within each case study, it was always assumed that 

both greenfield and repowering decisions would be of the same size (i.e., same rated capacity) and 

thus can be fairly compared. 

• Case studies were developed for plants in 

the Northeast, on the West Coast, and in 

the upper Midwest

• With the exception of the West Coast plant 

repowering, at the present time, does not 

appear to be overly compelling

• These results are consistent with decisions 

made on the ground and the results of the 

prior conceptual analysis

• Age and estimated project financials are the 

primary variables affecting these results 

• An assumed lower capacity factor for the 

greenfield investment option on the West 

Coast also supports repowering relative to 

other regions where high quality resources 

remain available
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Future Equipment Demand

• Supply chain demand can be 

approximated based on calculated 

lifetimes

•

Estimates assume:

o 25% of existing facilities repower at 20 years 

o 50% repower at 25 years of operation

o Remaining 25% of the existing fleet are 

assumed to continue to operate after 25 

years or to be decommissioned

• By in large U.S. repowering activity can 

be expected to remain rather modest 

until the mid- to late-2020s, achieving 

cumulative levels of 14 GW by 2030

• Repowering demand could be 

expected to remain strong after 2030, 

based on the assumed lifetimes 

applied here as well as recent and 

projected average installation levels

Source: Lantz et al., 2013; Note: Results assume 1 MW of existing capacity is replaced by 1 

MW of repowered capacity .
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Key Takeaways

• In the U.S., projects that continue to operate in the black after 20 years generally 

have little incentive to repower, relative to investing in new greenfield sites

• The balance tends to tip towards repowering sometime between 20 and 25 years 

of operations, but may be even later for more recent plants, depending on future 

operations costs

• Partial repowering that only results in modest cost savings relative to full 

repowering can be expected have minimal impact on the market

• Repowering demand outside of California is not likely to have a noticeable 

impact until the mid- to late 2020s, but assuming healthy levels of wind 

installations into the future could ultimately constitute a large portion of the U.S. 

wind industry

• A number of variables could alter these conclusions and include:

o Technology advancement

o Wind resource quality, for new greenfield plants

o Prices paid for wind generation, now and in the future

o Operations expenditures escalation rates (and plant performance generally)

o Cost savings achieved by repowering, relative to greenfield development
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Additional Information and Contact Details

• For additional reading, the full 

report and associated references 

can be found here: 

http://www.nrel.gov/docs/fy14

osti/60535.pdf

• For specific questions email: 

eric.lantz@nrel.gov