Performance - Wind Energy: Renewable Energy and the Environment - page 151

The wind turbines manufactured in Denmark were more massive and captured over 50% of the
California wind farm market from 1982 to 1985. This was due to their more rugged construction,
and they were more reliable. However, after 5 years, a major problem developed with deterioration
of fiberglass-reinforced plastic (FRP) blades at the root due to fatigue. The repair and replacement
market for blades was estimated at $80 million.
8.2 WINDSTATS
WindStats Newsletter [4] contains reports and wind energy production tables on thousands of wind
turbines: ID, manufacturer, kilowatt rating, swept area, tower height, estimated annual energy pro-
duction, monthly and quarterly energy production, quarterly capacity factor, specific output (kWh/
m 2 and kWh/kW), annual production for the previous 1 or 2 years, and date installed. In addition
for Denmark, there is information on reliability. The information for wind turbines in Denmark is
available online. The quarterly reports of the California Energy Commission and the monthly val-
ues in the WINDSTATS provide better information on load matching to utilities.
8.3 WIND FARM PERFORMANCE
Capacity factors have improved with the newer and larger wind turbines, so it is expected that wind
farms installed from 2000 on will have better capacity factors than the older installations The early
wind farms in California had average capacity factors below 20%, while wind farms in good to excel-
lent wind regimes with new wind turbines should have capacity factors from 35 to 40%. Availability
and capacity factor are related, because if the wind turbines are having operational problems, avail-
ability and capacity factors will be low. For example, for the first year, there were problems at Horns
Rev, an offshore wind farm in Denmark, so the capacity factor was only 26%; however, the next year
it reached the expected value. At the offshore wind farm Scroby Sands (thirty wind turbines, 60 MW)
in the United Kingdom, energy production was limited in the first year of operation. There were
numerous mechanical problems, with 27 intermediate-speed and 12 high-speed gearbox bearings
replaced, along with four generators. So the capacity factor for the first year was 29%, rather than the
predicted 40%. Another example is a 38-turbine, 80 MW wind farm where there were software prob-
lems and then blade problems. One year after installation thirteen turbines were still not operational.
All were expected to be operational in the second year.
8.3.1 C ALIFORNIA W IND F ARMS
The California Energy Commission (CEC) instituted a program in 1984 for Wind Performance
Reporting System regulations [5]. All California wind projects greater than 100 kW that sell electricity
to a power purchaser have to report quarterly performance. The quarterly reports contain the following
information: turbine manufacturers, model numbers, rotor diameters and kilowatter ratings, number
of cumulative and new turbines installed, the projected output per turbine, the output for each turbine
model, and the output for the entire project. The annual report is a compilation of data from the four
quarters and contains summary tables reflecting resource areas. The reports do not provide information
on every wind energy project in California, as nonoperating wind projects and those turbines that do not
produce electricity for sale, such as those installed by utilities, government organizations, and research
facilities, do not file reports. Wind performance report summaries are available from 1985 [5].
Only small wind turbines, diameter of 10 to 18 m, 25 to 100 kW, were available in the early 1980s.
At the end of 1985, the largest installed capacity was U.S. Windpower, 181 MW, followed by Fayette,
146 MW. The wind farms produced 0.65 TWh, which was 45% of that predicted by the plant opera-
tors. Average capacity factor was 13%, which was much lower than the 20-30% reported in technical
reports. Foreign wind turbines, which were newer, had a capacity factor of 17%. The ten largest manu-
facturers had 80% of the installed capacity, and four of those had 53% of the installed capacity. The
average installed cost of the 10,900 wind turbines was $2,000/kW, with a range of $700 to $2,300.