Wind Industry and Gear Boxes

Uwe Roeper

Hamilton Dinner

November 17, 2009

ORTECH Power

• 40 staff • Engineers & Consultants

– Technical Due Diligence / IE– Wind resources assessment– Plans & Permits– Financial Analysis– Operations Support

Wind Energy in Canada (2008)

Source: CanWEA

• 526 MW added in 2008 = 2nd highest year•Capacity end 2008: 2,372 MW = Electricity for over 600,000 homes = 1% of Canada’s total demand

Wind Growth in Canada (MW)

Source: CanWEA

Wind in Canada (2009 & beyond)

• Current installed capacity (May 2009) – 2,550 MW• Project a total of 650 MW to be installed this year (2nd best

year ever), pushing Canada over the 3,000 MW mark• An additional 5,000 MW of projects are either contracted

or under construction• Provincial government targets, if fully achieved, would

result in 12,000 MW of installed capacity in Canada by 2015

Source: CanWEA

Gear Boxes – The Weak Link

• What is the role of gear boxes in wind turbines?

• Why are they getting so much attention from the wind community?

• How does this relate back to lubrication engineering?

Source: CanWEA

Design Issues• Gear boxes need to light weight but handle

large stresses:– Typical size 2500 HP / 90 m Rotor– Variable speeds & loads– Torsion from uneven wind loads

• Approaching practical design limits of available materials.

• Constant push for cheaper cost per unit energy.

How are things working out?• Underperformance has been a key topic at AWEA and

CanWEA over past 2 years.– Typical underperformance of 10% based on major investigations

of existing farms:• 59 facilities / 243 years = 11% below P50• 41 facilities / 113 years = 90% of P50• Range 80% to 105%

• Financial significance on affected projects is high.– Senior Lenders: reduced DSCR, increased risk– Equity: very large reduction in cash flow

GH (AWEA 2008) 70 WF yrs

0

5

10

15

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25

Actual vs P50

WF

yrs

GH actual P50 Log?

Cashflow & Underperformance

0

5

10

15

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30

100% 90% 80%

Actual vs P50 (at 70% debt)

$ M

M Equity

Debt

IRR=11% IRR=6%

IRR= -(1)%

MW=100, P=$89/MWh, L=70%, I=7%, CF=34.1%, CapEx=2.4,OpEx=16%, Term=20, TV=0

Potential Causes• Over prediction of:

– Wind– Efficiency– Mechanical Availability

• (including due to gear boxes)

1. Understand Wind related factorsAnnual Variations in Wind Speed and Energy Production

0.5

0.6

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0.9

1

1.1

1.2

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1.4

1978

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Year

No

rmal

ized

Win

d S

pee

d /

En

erg

y

Normalized Wind Speed

Normalized Wind Energy

Linear (Normalized Wind Energy)

0

100

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0 5 10 15 20

Wind Speed, m/s

Po

wer

Ou

tpu

t,

kW

10-min averages

Yaw mis-alignmentYaw mis-alignment

correctcorrectrotor planepositive negative

wind speed vector

gF

top view

+

2. Unterstand efficiency factors

3. Understand mechanical factors

Drive Train

Structurals

Generator

Gearbox

Rotor Hub

Mech. Brakes

Rotor Blades

Yaw/Pitch Sys.

Hydraulics

Sensors

Electronics

Electrical

Down time per failure [days]Annual failure frequency [-]1 0,75 0,5 0,25 0 2 4 6

Example

Pro-Active ReactiveCostsRepair & Refurbishment 95,000$ 225,000$ Crane Costs 76,932$ 100,000$ Lost Revenue - $1,008/Day 4 4,032$ 30 30,240$ Condition Monitoring Costs 5,000$ -$ Spare Component Carrying Costs 19,072$ -$

Total 200,036$ 355,240$

Gearbox Repair & Refurbishment Costs

Understand Parts Life Cycles

• While unscheduled minor maintenance is expected to remain fairly constant, major repair will occur in intervals and increase in cost with age.

• Outages will generally increase along with major repairs.

Annual Repair & Maintenance Expenditure (illustration)

$0

$10

$20

$30

$40

$50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Th

ou

sa

nd

s

Operating Year

$/W

TG

-yr

Manage Life Cycle CostLife Cycle Cost: Pro-active vs Reactive Maintenance Approach)

$0.0

$0.2

$0.4

$0.6

$0.8

$1.0

$1.2

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Mill

ion

s

Years

• 20-year life cycle costs for repair and outages can vary from under $0.4 mill/WTG (pro-active mtc.) to over $1 mill/WTG (reactive mtc.). High mechanical loads (turbulence, ice, defects) can further increase cost (up to $2 mill/WTG in extreme cases).

Prevention Strategies?

• Early detection• Preventative maintenance

For gear boxes early detection is key

Most wind farms have an inadequate preventative maintenance program,parts inventory and supply chain.

Use Condition Monitoring

AFTER

BEFORE

Utilize Inspection Tools

Other Prevention Strategies?

• Improve design.

• Manage mechanical loads.

• Improve … lubrication?

Wind & Gear Boxes

• Rapid growth in wind is creating engineering challenges for mechanical design and life cycle expectations.

• Gear box failures are central to the life cycle economics of wind farms.

• More can be done to improve life expectancy on this key component.