HomeMy WebLinkAboutSub-Arctic Conditions with Severe Rime Icing Yukon Energy Corp Conference 03-2001
WIND POWER DEVELOPMENT IN
SUB-ARCTIC CONDITIONS WITH SEVERE RIME ICING
by
John F. Maissan, P.Eng.,
Director, Technical Services
Yukon Energy Corporation
Circumpolar Climate Change Summit and Exposition
March 19-21, 2001
Whitehorse, Yukon
Canada
WIND POWER DEVELOPMENT IN
SUB-ARCTIC CONDITIONS WITH SEVERE RIME ICING
by
John F. Maissan, P. Eng., Director, Technical Services
Yukon Energy Corporation
P. O. Box 5920
Whitehorse, Yukon
Y1A 5L6
Canada
Telephone (867) 393-5347
Fax (867) 393-5322
INTRODUCTION
Yukon is the North-Westerly most part of Canada and lies immediately East of Alaska. It
has a population of about 33,000 people, two thirds of which live in the capital city,
Whitehorse, situated in South central Yukon.
Electrical energy is supplied principally from two hydro-electric plants located on the
main (Southern) power grid and a third on a small grid in central Yukon. However,
peaking energy and capacity are normally supplied by diesel generators. As well, there
are 8 communities that are supplied by entirely by diesel plants because they are not
connected to either of these hydro based power grids.
With the mining industry in full operation, electrical loads can peak at up to 78 MW in
the main grid in the coldest days of winter. Annual energy requirement with this mining
load on is about 450 GWh. At present the mining load is shut down, resulting in peak
loads of just over 50 MW and annual energy requirements of only 250 GWh (there is
now a hydro-electric energy surplus). In the diesel served communities the annual
energy requirement totals about 50 GWh.
The climate in Whitehorse is sub-arctic, mean daily January lows are -25°C with the
lowest temperatures around -40°C, and occasionally to -45°C or lower. Weather data
analyses have shown that at altitudes of 4,000 to 6,000 feet rime icing can occur from
800 to 1200 hours per year -- equivalent to a continuous duration of 4 to 7 weeks per
year. Rime icing is the buildup of ice on anything solid from moist, supersaturated air at
sub-zero temperatures. Essentially whenever and wherever there is a cloud on a
mountain there is rime icing (cover photograph). Rime ice looks like the pretty frost that
builds up on trees around open water in the winter. In our location rime icing is most
severe in the early winter: mid October to the end of December. Severe rime ice on
wind monitoring equipment is illustrated in Photograph 1.
BACKGROUND
The potential for commercial wind power generation in Yukon was investigated in the
early and late 1980s on the basis of data from airports and two wind monitoring stations.
In all cases the conclusion was that it was not economic.
In 1990 two local citizens investigated Environment Canada’s upper air data and found
that wind speeds increased substantially with altitude. This led to the establishment of a
65 foot (20 meter) wind monitoring station on a shoulder of Mt. Sumanik that is known
locally as Haeckel Hill, located west of the city. This site has an altitude of about 4,700
feet (1430 meters), about 2500 feet above the valley floor, and consists of a ridge
perpendicular to the prevailing wind. Road access and a single phase power line to a
forest fire look out tower located on top were positive factors in the selection of this site.
Monitoring results confirmed the higher wind speeds at higher altitudes, but also found
severe rime icing conditions at the site. Another interesting feature, since confirmed by
long term monitoring, is that inversions keep the temperatures from reaching the low
extremes, it seldom drops below -30°C (-22°F) even with valley temperatures down to -
45°C (-50°F) or lower.
A subsequent analysis of upper air data (Table 1) showed that the annual average wind
speed at 4,000 feet was 6.6 m/s (meters per second), at 5,000 feet was 6.9 m/s, and at
6,000 feet was 7.3 m/s. Since the kinetic energy in wind increases with the cube of the
wind speed, these are significantly better than the 3.9 m/s long term average at the
airport. It is also very significant that the wind speeds are much higher in winter than in
summer, almost perfectly following the seasonal electrical load profile. It was felt that
with these wind speeds commercial wind power could be cheaper than diesel
generation if the low temperatures and the effects of the rime icing could be overcome.
Producing electrical power at costs below the cost of diesel generation was and remains
our primary goal. Environmental benefits are the icing on the cake.
THE FIRST WIND TURBINE
Since the monitoring generally confirmed the upper air wind regime, and found that
severe rime icing was present there, it was decided, in 1992, that a program of
adaptation of commercial wind generating equipment to this climate was needed. With
our limited resources we decided that we could not do anything other than take existing,
proven commercial equipment and try to adapt this to our conditions. Several large,
reputable manufacturers were considered and Bonus Energy A/S of Denmark was
selected for their 150 kW MARK III unit. This 150 kW machine, a conventional three
bladed, horizontal axis, up wind and stall regulated design, represented the small end of
the commercial range available and therefore the lowest capital cost. Bonus was a large
proven commercial equipment supplier with a good reputation, had some northern
experience, was willing to work with Yukon Energy on modifications, and had a hinged
tower design for a winch up raising that did not require a large crane to be brought in
from southern Canada.
In consultation with Bonus a number of modifications were made to their standard
design. A hinged, winch up 30 meter tower was an important feature. To overcome the
effects of the cold, low temperature tolerant steels were selected for the tower plus
other key components, and synthetic lubricants (including hydraulic fluid) were used
throughout. Electric heaters, controlled by thermostats, were installed on the gearbox,
in the generator, in the computer control cabinet, and in the radio communications
cabinet.
To overcome rime icing effects the anemometer and wind vane used to control the
turbine were equipped with heated bearings. The blades were equipped with heating
strips about 6 inches wide and running along the entire length of the leading edge. The
heat output was about 1/4 watt per square inch, or 1,700 watts for all three blades. An
ice detector to turn the blade heating on and off was also supplied. The power
production target was set at 300,000 kWh per year representing a capacity factor of
22.8% (Table 1).
A firm order for this unit, plus a two year service agreement from the manufacturer, was
placed in December 1992. The turbine was erected in July of 1993 (Photograph 2) and
was commissioned on August 13. The project cost about $CDN 800,000, of which
$CDN 200,000 was for upgrading the road and power line. Yukon Energy received a
grant of $300,000 from government sources toward the project.
PROJECT RESULTS
Rime icing causes were briefly described in the introduction. The practical effects can
be substantial. Any solid object accumulates ice which “grows” into the wind
(Photograph 3). Trees become ice domes, towers become ice posts, power lines grow
to six or eight inches in diameter, and chain link fences become solid walls. As you can
see it is no wonder that exposed equipment has difficulty working under these
conditions. Low temperatures and severe rime icing are the challenges we need to
overcome.
The following features have worked well and have not needed further attention:
1. The winch up tower worked well even though it is not as easy to winch up or
down as expected.
2. The low temperature steels have not been a problem so far.
3. Lubrication with synthetic products has worked well.
4. The heating systems in the gearbox, generator, and electronic cabinets have
been very reliable.
Aspects of the project that did not work initially but have since been overcome are:
1. The heated bearing anemometer and wind vane were still immobilized by ice and
were replaced with fully heated Hydro-Tech instruments which have not iced up
(Photograph 1).
2. The overhead power line was causing about five outages per month due to the
heavy accumulation of ice in combination with wind, and was replaced with a
buried cable which is not affected by the ice.
3. The Ice detector supplied with the turbine was not effective and was removed
from the control circuit. The heating circuits are now simply switched on for the
winter. A Rosemount ice detector was purchased in 1996 and has been running
reliably on site since then, but has not been installed into the turbine control
circuit. This ice detector has indicated that we average over 800 hours of rime
icing per year on the site.
One aspect of the project that did not work and has not been overcome is the inability of
the electrical contacts between the main portion of the blades and the tips to work
reliably under icing conditions. Several redesigns have also failed to operate reliably.
The leading edge blade heaters (1/4 watt per square inch) have worked reasonably well
even though one burnt out in 1996. We replaced them all in 1998 with heaters 12
inches wide, rather than 6 inches, to improve performance in very severe rime icing and
in very cold temperature conditions. Perhaps because of other problems and advances
we have not been able to attribute specific production improvements to the larger
heaters.
The effect of rime icing on the blades of the wind turbine is such an important issue that
it is worth examining in detail. Without blade heaters rime ice builds up especially
heavily on the leading edges, and the build up increases with distance from the blade
root (Photograph 4). It seems to be directly related to the velocity at any point and
therefor perhaps the amount of moisture or moist ice contacted. When shut down the
ice builds up on the edges of the blade surface facing the wind, the pressure side.
When running through an icing event the ice build up on the “back”, or suction side, of
the blade is much less than on the “front” (Photograph 5). Ice can also build up on the
trailing edge. Power production drops off dramatically when the blades are coated with
rime ice and without leading edge blade heaters can stop altogether (Graph 1).
The 6 inch wide heaters did, under lighter icing conditions, keep portions of the blade
downwind of the heater clear (Photograph 6). Under heavier icing conditions ice would
build up on the blade right up to the heater (Photograph 7). Build up of ice on the
leading edges did not occur except under the most severe conditions, and it cleared off
quite quickly afterwards. It was from this that we concluded that more heat on the front
of the blade in the form of wider leading edge heaters would be of benefit if the
increased area was applied to the front (pressure side) of the blade. It was also obvious
that the leading edges of the blade tip would need to be heated to minimize the air drag
and associated production losses.
One aspect of the project that was very positive was the bird monitoring work. Concern
over the possibility of bird kills in collision with the turbine blades, especially during
spring and fall migrations, led to a five year monitoring program. It was found that the
migrating waterfowl, at least, stayed lower down in the valley well below the altitude of
the turbine. The only bird mortality documented in the program was a grouse that flew
into the chain link fence.
POWER PRODUCTION
From a production perspective the project has not yet met the target but, all considered,
we are satisfied with our accomplishments. In the first year we solved the power line
and control instrument problems. Once those were resolved performance improved
substantially.
In the third year of operation we had a failure of one of the blade heaters early in winter
and we had to operate without any leading edge heat for the rest of the winter. With the
heaters working on only two of the blades there was a significant blade weight
imbalance. At this time annual “losses” due to rime icing were estimated to be in the
range of 60,000 to 70,000 kWh per year, about 20% of the production target.
Repairs to the power line (a local feeder) were made in 1996 and since that time there
have been very few of the electronic problems that bothered us early on, and turbine
availability has been very high. Also in 1996 we “painted” the blades with a black
coloured coating called StaClean. We believed that the solar heating from the black
colour would assist in clearing the blades of accumulated rime ice, and we felt that the
special low adhesion formula for ice could be beneficial too. We saw an immediate
noticeable improvement in performance, 1998 and 1999 have been the best production
years yet. Photograph 8 shows accumulated ice shedding from the blades.
On the whole we are pleased with the performance, especially considering where the
turbine is physically located, the unfamiliarity of maintenance personnel with this type of
equipment, and our dependence on a few key people. Due to the ladder being outside
for the top portion of the tower and the weather exposed servicing, maintenance is not
done during severe weather conditions. Detailed monthly performance statistics from
project commissioning are presented in Table 2. Annual figures based on revenue
metering which commenced in July 1994 is presented in Table 3.
THE SECOND WIND TURBINE
With funding from the Yukon government, the Yukon Energy installed a new larger wind
turbine this past September, a Vestas 660 kW V47 LT II, low temperature version
(photograph 9). This turbine incorporates most of the features that we believe will move
wind energy from the development phase into commercial viability. This machine is a
pitch regulated machine designed for unrestricted operation down to -30° C (-22° F). It
was fitted with fully heated wind instruments, StaClean coated (black) blades and
leading edge blade heaters. Our experience with the stall regulated 150 kW machine
have convinced us that a pitch regulated machine will lose less power when affected by
rime ice as the lowering of the stall wind speed is not as critical with the pitch regulation
design. In the higher wind speeds the blades will remain pitched to a more aggressive
angle until full output is achieved. Since the blades do not have tip brakes maintaining
electrical continuity and effective heating to the very tip should not be a problem.
Two features that we would have liked to have had but were not able to get in a turbine
in the 500 to 1,000 kW size range this time, were a full surface blade heating system,
and an operating temperature range down to -40°.
The new turbine was installation was completed in mid September (photograph 10).
Detailed performance comparisons between the two turbines has not been possible so
far. We are still in the process of fine tuning the various operating and control systems.
These analyses will be part of our work in the coming years.
SUGGESTIONS FOR SIMILAR APPLICATIONS
For anyone contemplating a wind turbine in a cold, severe rime icing environment such
as Haeckel Hill, which is on the warmer side of typical of the interior of Yukon and
Alaska, we would recommend the following:
1. Low temperature steels
2. Low temperature synthetic lubricants and fluids
3. Equipment heaters (gearbox, generator, control cabinets)
4. Fully heated wind instruments
5. Black coloured fluorourethane (StaClean) coated blades
6. Full surface blade heating if available, or otherwise leading edge heaters at least
12 inches wide
7. For simplicity and reliability in leading edge heating one piece blades would be
better than the two piece such as we have on our Bonus machine
8. Tubular tower for “indoor” climbing and maintenance work for shelter from the
weather
9. Pitch or active stall regulation as we believe this will result in higher power
production
CONCLUSION
In conclusion, substantial progress has been made in understanding the effects of rime
icing on wind turbines and in learning how to overcome them. It is our goal to establish
a track record of performance under these conditions that puts wind power into the list
of realistic and practical power supply options available to us in Yukon. Like the trees
that survive in these conditions we northerners need to stand together, we need to be
tough, we need to be innovative, we need to be persistent, and, most importantly, we
need a strong positive attitude.
REFERENCES
Craig, David F., and Craig, Douglas B., P.Eng., Wind Energy Potential Whitehorse,
Yukon, Boreal Alternate Energy Centre, August 1990
Craig, Douglas B., and Craig, David F. , Wind Energy Potential Whitehorse, Yukon
Report Number 2, Boreal Alternate Energy Centre, April 1991
Craig, David, B. Eng., and Craig, Douglas, Ph.D., P. Eng., Wind Energy Potential
Whitehorse, Yukon, Report Number 3, Estimate of Energy Production From Wind
Monitoring Stations on Haeckel Hill and Mount Sumanik, Boreal Alternate Energy
Centre, October 1992
Craig, David, M.Sc., P. Eng., and Craig, D. B. Ph.D., P. Eng., Wind Energy Potential
Whitehorse, Yukon, Report #4, An Investigation of Icing Events on Haeckel Hill, Boreal
Alternate Energy Centre, December 1995
Craig, D. F., M.Sc., and Craig, D. B., Ph.D., Monitoring of Icing Events on Fjells in
Northern Canada, Boreal Alternate Energy Centre, March 1994
Lorti, Grant M., Environmental Impact assessment for the Proposed Haeckel Hill Wind
Turbine Demonstration Project, October 1992
Maissan, John F., Adaptation of a Wind Turbine for Sub-Arctic Conditions with Severe
Rime Icing, Yukon Energy Corporation, 1996
Mossop, D. H., and Egli, K., Bird Strike Monitoring, Haeckel Hill Wind Turbine, Summer
1993, Government of Yukon, Department of Renewable Resources, November 1993
Mossop, D. H., Five Years of Monitoring Bird Strike Potential at a Mountain-Top Wind
Turbine, Yukon Territory, Northern Research Institute, Yukon College, 1997
Nor’wester Energy Systems Ltd., Analysis of Upper Air Wind Speed and Direction Data
Collected at Whitehorse, Yukon 1980 to 1989, September 1991
Nor’wester Energy Systems Ltd., The Prediction of Icing Events at 4000 to 6000 Feet
Elevation at Whitehorse, Yukon, August 1992
Nor’wester Energy Systems Ltd., The Wind Resource and Icing Environment at
Whitehorse, Yukon 1980-1995, July 1995
Yukon Energy Corporation, Proposal for Development Wind Turbine, Haeckel Hill,
Whitehorse, Yukon, October 1992
Yukon Energy Corporation, Unpublished Reports, 1994-2000
TABLE 1
WHITEHORSE UPPER AIR WIND SPEEDS AND BONUS PRODUCTION TARGETS
Whitehorse, Yukon Bonus 150
Mean Wind Speeds 1980 - 1995 Production Targets
(Airport) Target Target Capacity
Month 2305' ASL 4000' ASL 5000' ASL 6000' ASL kWh Factor
January 3.6 8.5 8.7 9.2 30.000 26.9%
February 4.1 7.9 8.3 9.0 28.000 27.8%
March 4.0 6.9 7.3 7.7 28.000 25.1%
April 4.0 6.2 6.5 6.8 25.000 23.1%
May 4.0 5.6 5.8 6.1 24.000 21.5%
June 3.6 5.0 5.0 5.3 15.000 13.9%
July 3.4 4.3 4.6 4.8 15.000 13.4%
August 3.3 5.5 5.5 5.8 18.000 16.1%
September 3.4 6.6 6.9 7.6 27.000 25.0%
October 4.6 7.7 8.1 8.5 30.000 26.9%
November 4.4 7.9 8.3 8.4 30.000 27.8%
December 4.0 8.2 8.5 9.0 30.000 26.9%
Annual 3.9 6.6 6.9 7.3 300.000 22.8%
Graph 1 Rime Icing Effects on Power Production Curves
Table 2 Detailed Production Record
WIND TURBINE PRODUCTION DATA
Month
Prod.
(kWh)
Total
Hours
Hours in
Prod.
Maint.
Hours
Break
Down
Hours
Grid
Outage
Hours
Cap.
Factor
Turbine
Avail.
Overall
Avail.
Revenue
Meter
Gross
Cap.
Factor
Aug-93 10,949 408 222 0 0 0 17.9%100.0%100.0%
Sep-93 19,290 720 379 7 19 58 17.9%96.4%88.3%
Oct-93 15,890 744 309 12 48 24 14.2%91.9%88.7%
Nov-93 21,331 720 331 14 1 163 19.8%97.9%75.3%
Dec-93 18,728 744 317 36 3 186 16.8%94.8%69.8%
Tot-93 86,188 3,336 1,558 69 71 431 17.2%95.8%82.9%
Jan-94 4,896 744 152 40 96 300 4.4%81.7%41.4%
Feb-94 11,335 672 320 37 0 0 11.2%94.5%94.5%
Mar-94 38,262 744 652 4 9 0 34.3%98.3%98.3%
Apr-94 26,666 720 570 12 0 0 24.7%98.3%98.3%
May-94 24,227 744 505 0 26 0 21.7%96.6%96.6%
Jun-94 14,849 720 225 0 0 6 13.7%100.0%99.2%
Jul-94 15,307 744 400 0 0 3 13.7%100.0%99.6%17320 15.5%
Aug-94 10,980 744 385 5 61 26 9.8%91.2%87.7%12090 10.8%
Sep-94 28,636 720 542 0 17 0 26.5%97.6%97.6%29230 27.1%
Oct-94 28,326 744 549 37 0 0 25.4%95.0%95.0%30980 27.8%
Nov-94 19,415 720 422 0 67 0 18.0%90.7%90.7%22430 20.8%
Dec-94 20,541 744 442 0 0 0 18.4%100.0%100.0%22144 19.8%
Tot-94 243,440 8,760 5,164 135 276 335 18.5%95.3%91.5%
Jan-95 21,363 744 511 0 0 12 19.1%100.0%98.4%23760 21.3%
Feb-95 27,379 672 423 0 0 0 27.2%100.0%100.0%29620 29.4%
Mar-95 18,060 744 344 0 288 0 16.2%61.3%61.3%18790 16.8%
Apr-95 24,299 720 559 0 0 0 22.5%100.0%100.0%27190 25.2%
May-95 20,395 744 478 12 0 7 18.3%98.4%97.4%22210 19.9%
Jun-95 12,751 720 339 0 99 2 11.8%86.3%86.1%14380 13.3%
Jul-95 8,298 744 306 0 49 3 7.4%93.4%93.1%9230 8.3%
Aug-95 14,785 744 306 0 0 0 13.2%100.0%100.0%16080 14.4%
Sep-95 31,919 720 571 8 0 0 29.6%98.9%98.9%34030 31.5%
Oct-95 13,911 744 368 6 0 1 12.5%99.2%99.0%15742 14.1%
Nov-95 11,265 720 313 9 0 2 10.4%98.8%98.6%11991 11.1%
Dec-95 22,736 744 477 3 11 9 20.4%98.2%97.0%25226 22.6%
Tot-95 227,161 8,760 4,995 37 447 35 17.3%94.5%94.1%248249 18.9%
Jan-96 971 744 42 0 702 0 0.9%5.6%5.6%1020 0.9%
Feb-96 26,597 696 470 16 0 2 25.5%97.7%97.5%29257 28.0%
Mar-96 38,309 744 559 0 0 0 34.3%100.0%100.0%41599 37.3%
Apr-96 12,060 720 226 3 114 273 11.2%83.8%45.8%14408 13.3%
May-96 16,275 744 412 6 81 0 14.6%88.4%88.4%18009 16.1%
Jun-96 17,488 720 496 0 0 2 16.2%100.0%99.7%19130 17.7%
Jul-96 6,216 744 259 192 7 0 5.6%73.3%73.3%7317 6.6%
Aug-96 11,037 744 391 205 0 0 9.9%72.4%72.4%11803 10.6%
Sep-96 24,850 720 494 6 0 10 23.0%99.2%97.8%27490 25.5%
Oct-96 14,376 744 377 43 0 0 12.9%94.2%94.2%13502 12.1%
Nov-96 24,890 720 475 0 0 0 23.0%100.0%100.0%27716 25.7%
Dec-96 27,601 744 441 6 0 0 24.7%99.2%99.2%31604 28.3%
Tot-96 220,670 8,784 4,642 476 904 287 16.7%84.3%81.0%242,855 18.4%
Month
Prod.
(kWh)
Total
Hours
Hours in
Prod.
Maint.
Hours
Break
Down
Hours
Grid
Outage
Hours
Cap.
Factor
Turbine
Avail.
Overall
Avail.
Revenue
Meter
Gross
Cap.
Factor
Jan-98 14,600 744 n/a 0 0 n/a 13.1%100.0%n/a 15698 14.1%
Feb-98 31080 672 n/a 0 0 n/a 30.8%100.0%n/a 32048 31.8%
Mar-98 26080 744 n/a 0 0 n/a 23.4%100.0%n/a 26980 24.2%
Apr-98 31570 720 n/a 00n/a 29.2%100.0%n/a 32454 30.1%
May-98 32370 744 n/a 0 0 n/a 29.0%100.0%n/a 33227 29.8%
Jun-98 13280 720 n/a 25 0 n/a 12.3%96.5%n/a 13932 12.9%
Jul-98 17600 744 n/a 111 0 n/a 15.8%85.1%n/a 17781 15.9%
Aug-98 22260 744 n/a 54 0 n/a 19.9%92.7%n/a 22465 20.1%
Sep-98 21790 720 n/a 0 0 n/a 20.2%100.0%n/a 22001 20.4%
Oct-98 23130 744 n/a 2.5 0 n/a 20.7%99.7%n/a 24984 22.4%
Nov-98 10310 720 n/a 0 0 n/a 9.5%100.0%n/a 10937 10.1%
Dec-98 14520 744 n/a 0 2 n/a 13.0%99.7%n/a 17623 15.8%
Tot-98 258,590 8,760 n/a 193 2 n/a 19.7%97.8%n/a 270,130 20.6%
Jan-99 n/a 744 n/a 0 0 1 n/a 100.0%99.9%21,410 19.2%
Feb-99 n/a 672 n/a 0 0 0 n/a 100.0%100.0%23,310 23.1%
Mar-99 28,014 744 566 1 0 1 25.1%99.8%99.8%29,590 26.5%
Apr-99 25,788 720 532 0 0 0 23.9%100.0%100.0%26,920 24.9%
May-99 18,545 744 489 0 0 0 16.6%100.0%100.0%19,980 17.9%
Jun-99 12,726 720 412 0 0 1 11.8%100.0%99.9%14,940 13.8%
Jul-99 18,716 744 437 0 0 1 16.8%100.0%99.9%20,680 18.5%
Aug-99 11,465 744 416 0 3 1 10.3%99.6%99.5%12,730 11.4%
Sep-99 27,451 720 496 0 21 2 25.4%97.0%96.8%29,620 27.4%
Oct-99 25,998 744 518 9 4 5 23.3%98.3%97.7%27,530 24.7%
Nov-99 12,374 720 303 0 50 2 11.5%93.1%92.8%12,290 11.4%
Dec-99 34,448 744 593 0 8 0 30.9%99.0%99.0%34,780 31.2%
Tot-99 215,525 8,760 4,762 10 86 11 16.4%98.9%98.8%273,780 20.8%
Jan-00 22,524 744 438 0 0 0 20.2%100.0%100.0%21,080 18.9%
Feb-00 13,961 696 426 0 0 0 13.4%100.0%100.0%14,940 14.3%
Mar-00 31,152 744 570 0 13 0 27.9%98.3%98.3%31,070 27.8%
Apr-00 24,539 720 502 1 0 1 22.7%99.8%99.7%25,830 23.9%
May-00 12,867 744 411 0 80 0 11.5%89.2%89.2%13,070 11.7%
Jun-00 10,135 720 386 14 0 0 9.4%98.1%98.1%9,950 9.2%
Jul-00 14,257 744 456 0 0 1 12.8%100.0%99.9%16,400 14.7%
Aug-00 18,802 744 496 0 0 0 16.8%100.0%100.0%19,410 17.4%
Sep-00 20,404 720 544 2 0 0 18.9%99.7%99.7%20,602 19.1%
Oct-00 30,905 744 602 0 3 0 27.7%99.6%99.6%30,768 27.6%
Nov-00 19,963 720 402 0 1 0 18.5%99.9%99.9%19,420 18.0%
Dec-00 23,296 744 472 0 0 0 20.9%100.0%100.0%22,660 20.3%
Tot-00 242,805 8,784 5,705 17 97 1 18.4%98.7%98.7%245,200 18.6%
TOTAL 1,720,618 64,704 30,953 950 1,882 1,155 17.7%95.6%93.8%
Year Hours Actual gross Actual gross
kWh C.F.%
1994 8,760 254,429 19.4%
1995 8,760 248,249 18.9%
1996 8,784 242,855 18.4%
1997 8,760 242,307 18.4%
1998 8,760 270,130 20.6%
1999 8,760 273,780 20.8%
2000 8,784 245,200 18.6%
Yukon Energy 150 kW Bonus Wind Turbine - Annual Production
TABLE 3
ANNUAL PRODUCTION BASED ON REVENUE METERING
(REVENUE METERING COMMENCED IN JULY 1994)
Photograph 1: Rime ice on monitoring equipment, only heated instruments stay clear
Photograph 2: the first wind turbine being winched up on hinged tip up tower
Photograph 3: turbine heavily iced, did not run through icing period
Photograph 4: wedge shaped ice builds up on the blades when running through icing
events – leading edge heaters not working
Photograph 5: wedge shape build up from back, note clear back of blade –
leading edge heaters not working
Photograph 6: in less severe rime icing the effect of the leading edge heaters
extends past the leading edge
Photograph 7: in severe icing conditions the effect of the leading edge heaters
does not extend as far
Photograph 8: accumulated ice shedding from black blades
Photograph 9: the second wind turbine being installed
Photograph 10: both wind turbines in place