Yukon Wind EnergyWind Energy Research, Development

and Operation in Harsh Arctic Environments

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For:

International Wind-Diesel WorkshopMarch 8-11, 2011 Girdwood, Alaska

By John Maissan, P.Eng.andJP Pinard, PhD, P.Eng.

Introduction• History of wind in Yukon• Wind in mountainous terrain• Icing and measurements• Wind turbine operations in Yukon

– The Bonus 150 kW– The Vestas V47 660 kW

• Wind turbines in the north

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History of Wind in Yukon• First wind measurements were made in 1980’s,

results were negative.• Serious research began in the early 1990’s

focused on mountaintops.• 1993 the Bonus 150 kW was installed with blade

heating.• Wind program expanded to cover almost every

community.• The Vestas V47 660kW was installed in 2000• The wind research is ongoing...

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Short Lesson on Wind in Mountainous Terrain

• Inversions are a mainstay affecting wind with respect to height.

• Winds in valleys are different from winds on mountaintops (geostrophic).

• Winds are commercially better on mtn tops, however... icing

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Northern Wind Climate: Stratification

• The atmosphere is stability stratified• Air tends to flow in layers• Cold air sits at the valley bottom and is

difficult to push along by air above• Air in valleys flow like rivers

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Wind and Temperature profiles in a Yukon Valley

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Haeckel Hill

Profiles from Whitehorse weather balloon station

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JP Pinard photo

JP Pinard photo

JP Pinard photo

Northern Wind Climate: Seasonal variation

• In winter larger temperature difference from equator to North pole

• Means larger pressure difference -> windier.• Winds on the mountaintops tend to increase in the

winter• However, Winds in the valleys tend to decrease in

the winter: due to temperature inversion.

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From Pinard, 2007

2400 m ASL: above the mountaintops

900 m ASL: within the valley

7.9 m/s mean wind speed from this sector

Inversion in effect here

When observing upper winds from this direction only

Valley winds are like this

Northern Wind Climate: wind pattern changes with height

• Winds above mountaintops are typically geostrophic: they follow the pressure contours, high pressure to the right when facing downwind

• Winds at mountaintops can be controlled by orography (mtn topography)

• Winds within valleys tend to follow the valley axis.• Valley winds move from high pressure to low

pressure areas.

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From Pinard, 2007

2400 m ASL: above the mountaintops

HIGH

LOW

HIGH

HIGH

HIGH

LOW

LOW

LOW

Northern Wind Climate: Mountaintop icing

• Icing is caused by supercooled water droplets: liquid water at 0 -> -20C temperatures.

• Super-cooled water solidifies onto a solid surface.• Typically when there is a cloud at freezing

temperatures, there is icing.• Mountaintops and coasts are prone to icing• Icing is worst in fall when air temperature drops

below freezing and lakes still open.

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John Maissan photo

Icing issues with measurements

• Icing can destroy met masts/towers• Icing contaminates wind sensors• Icing has been difficult to prevent• Icing has been difficult to detect and measure

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Icing on Towers• Ice can weight down heavily on the guy lines of a tower• Tower must support the added weight and vibration in

high winds• Need tower tubes and guy wires of heavy gauge.• Lattice towers have more surface for ice to cling to.• Booms need to be sturdy

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Yukon Energy photo

JP Pinard photo

Icing on Sensors• Ice contaminates sensors• Ice throw can be damaging• Plastic components of sensors can break • Perceived wind speed is reduced under light icing

and is hard to detect• Heavy icing is more obvious in data

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JP Pinard photo

Yukon Energy photo

Anti-Icing on sensors• Need full body ice prevention• Heated portions of sensors can still be covered by icing

stemming from non-heated part of the body• A variety of heated sensors with power requirements ranging

from 75 to 1500 watts have been tried.• Power supply is a problem in remote locations: energy

efficiency and management is critical• Need smaller sensor with less surface area to heat• To save energy use ice detector to detect icing and then turn

on heated sensor. This causes problems with the sensor: eg. bearing issues.

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Yukon Energy photo

Yukon Energy photo

Yukon Energy photo Yukon Energy photo

Yukon Energy photo

Detecting Ice• Two heated anemometers: one is always on; the other is

intermittent and comes on when slows.• Ice detector technology from aviation industry like the

Goodrich (formerly Rosemount) Ice Detectors: models 0871LH1 (available today) and 0872B12 (better but no longer available) have been tested.

• Ice detector technology is still in need of improvement• Need full body heating, however power is premium in remote

sites• Need physically smaller instruments with less surface area, so

that less power is required to heat and operate.

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Yukon Energy photo

Goodrich photo

JP Pinard photo

Wind Turbine Operations in Yukon:The Bonus 150 kW installed in 1993

Special Features– low-temperature-tolerant steels (to -30°C)– synthetic lubricants– six-inch wide heaters for the leading edges of the blades– heating systems in the gearbox, generator and electronic

cabinets– heated bearings for the wind vane and anemometer– hinged 30-metre tower capable of installation without a

large crane

Yukon Energy photo

Yukon Energy photo

Wind Turbine Operations in Yukon:The Bonus 150 kW installed in 1993

Challenges– Blade icing behind the heaters in severe icing

conditions– The heated-bearing anemometer iced up– The two-section blades meant that the blade tip

heaters often didn’t work, leading to icing and reduced output

– Turbine shutdown when discrepancy between anemometer and power output

Yukon Energy photo

Yukon Energy photo

Wind Turbine Operations in Yukon:The Bonus 150 kW installed in 1993

Solutions– Wider heaters were installed on leading edge to

extend the ice free blade area– A black-coloured fluorourethane (StaClean) coating

was applied to the blades to encourage ice shedding after warranty

– Installation of fully heated anemometer and wind vane eliminated rime icing problems with them

– Allow turbine to operate when power output below anemometer suggested output – right to nil

Yukon Energy photo

Wind Turbine Operations in Yukon:The Vestas V47 660kW, installed 2000

Features– Operation rated to -30C (“Arctic” version)– Pitch regulated– StaClean coated black blades– Twelve-inch heating strips for the blade leading edges– heating systems in the gearbox, generator and

electronic cabinets– Shorter tower (37m)

Yukon Energy photo

Wind Turbine Operations in Yukon:The Vestas V47 660kW, installed 2000

Challenges– Still icing downstream of surface heaters– Turbine shutdown when power output below 75% of

what it should beSolutions for Future

– Full surface blade heating– Ice detector controlled blade heating– Allow turbine to operate at reduced output as long as

no imbalance or vibration issues

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1-Jan-01 31-Jan-01 2-Mar-01 1-Apr-01 1-May-01 31-May-01 30-Jun-01 30-Jul-01 29-Aug-01 28-Sep-01 28-Oct-01 27-Nov-01 27-Dec-01

OutdoorTemp NRG

Icing

Icing and WTG Operations

• Blade heating properly designed works – need commercial availability

• Black surface works – assists in de-icing• Ice-phobic / hydro-phobic coatings appear to work• Rotor balance & vibration needs monitoring• Ice throw not a big issue with rime ice and in remote

locations

WTG in larger northern locationsFor northern industry or power grids

• Scale is somewhat smaller than mainstream grid-connected systems.

• Cranes are very expensive to deploy to remote locations• Wish list:

– Optional operation to -40°C– Towers & nacelles that require reduced crane size– More selection in 300kW to 1MW turbines– Optional blade heating when required– Expanded remote operational and maintenance

monitoring and control

WTG in small remote communities

• Scale is smaller than mainstream grid-connected systems• Cranes are very expensive to deploy to remote communities• Wish list:

– Optional operation to -40°C & blade heating– Tilt up towers that require no crane– More selection in 50 – 150 kW turbines– Simple generator and blade designs– Cookie cutter foundation and electrical integration designs to

reduce costs– Expanded remote operational and maintenance monitoring and

control

Thank You!

This and other related publications can be found at http://www.esc.gov.yk.ca/publications_yukon.html

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