20170925Utah_OCS 1.10 NREL_Presentation 1-28-2016.pdf

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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 Better utilization of high-value resource areas
o Improved grid support and interactions
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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U.S.Case Study
Projects that "operate in the black"have little cash Flow Analysis of 2003 Vintageincentivetorepower,relative to investingin new Wind Plant in 2025greenfieldsites
$14 -----------------------------------------------------------------------------
Around 20-25 years of operation,the choice I
between investingin greenfield sites and i s12 ------------------------------------------------------------------
repowering becomes viable but depends on:)
o Cost and performance of new technology i g sto ------------------------------------------------------------------
o Anticipatedenergy productionof comparable o½
greenfieId site ·°!sa -----------------------------------------------------
o Durability and reliabilityof turbine equipment
o Usefulnessof existing infrastructure a i $6 ---'------------------------------------
o Wholesale market electricity prices and existing jcontractualarrangements=$4 -----------------------------------------
Partial repowering solutions that can be realized 6
at a lower cost would likely prove more viable
o Analysis of partial repoweringassumes:Existing+Green Repower PartialRepower
-An increase in net capacity factor (NCF)from 30%to
3/%source:Lantz et al.2013.Note:data in the figure illustrate value gained or lost as a result of a
-A 15%cost reduction relative to a green field (~10%specific investment decision;as each of these plants is modeled at an equivalent size,the
relative to repowering).change in plant-specific net present value 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 net present value is highly correlated to plant size
NATIONAL RENEWABLE ENERGY LABORATORY 3
European Experience
Before Repowering After Repowering
Hub height [m]Hub height [m]
3500 ..50 400C
-Average full time hours
O 15mrotordiameter o 90
O 48mrotordiameter
3000 45 350C
2500 300C40
70
2000 250C
ee 35
60
1500 200C
30 50
1000 150Cz -Average full time hours g25O44mrotordiameter 40120mrotordiameter
5 84 1986 1988 1990 1992 1994 1996 1998 10Ë00 2002 2004 2006 2008 2010 2012
Year of Commissioning Year of Commissioning
Note different scales.
Source:Buzauet al.(forthcorning)
Repowered wind plants have an increased hub height (2X),rotor diameter (3X),and rated
capacity (5X),resulting in increased productivity.For example,the number of average
full time hours has increased about 20%.
The figures show an analysis of 48 wind plants in Denmark installed in the 1990s and
repowered in the 2000s.
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Research and Development Opportunities
To what extent can existing infrastructure be used to support
taller towers,larger rotors,and/or improved site layout to
increase project productivity?
o Could innovative drive-system and/or blade designs make partial
repowering financially attractive?
How will unused materials be recycled or repurposed?
Would improved energy capture at high-value resource areas
enable California to meet carbon emission reduction goals more
cost effectively than development of greenfield sites or importing
electricity from other states?
What technology innovations are needed to improve grid
support?And would enhanced grid services from repowered
wind projects affect California system reliability or transmission
expansion requirements more generally?
Would visual impacts be reduced?
Would avian and wildlife impacts be reduced?
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Sources and contact Information
Lantz,E.,M.Leventhal,I.Baring-Gould.2013.Wind Power Project
Repowering:Financial Feasibility,Decision Drivers,and Supply Chain
Effects (Technical Report).TP-6A20-60535.National Renewable
Energy Laboratory (NREL),Golden,CO (US).http://www.nrel.gov/docs/fy14osti/60535.pdf
Buzau,M.,Serrano-Gonzalez,J.,Lacal-Arántegui,R.(forthcoming).
Wind farm repowering:an analysis of wind farm performance.
Ongoing work,Joint Research Centre of the European Commission.
M.Maureen Hand,Ph.D.
National Renewable Energy Laboratory
Golden,CO USA
[e-mail]
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