RC Macaulay wrote: "A large portion of each windfarm is "out of
service for repairs" at any one time."
I mentioned that an EPRI study showed just the opposite: wind
turbines require less maintenance per KWH than most other generator
types. However, a study at a remote location with high winds did
reveal significant costs and downtime for operations and maintenance
(O&M). The costs were covered by the warrantee. Overall availability
for two types of turbine was 92%. The capacity factor for this
location was 32%, which means there is a lot of wind for a land site. See:
http://pepei.pennnet.com/Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID=256006&VERSION_NUM=2&p=6
92% compares favorably to nuclear and combustion generation when you
take into account the time required for maintenance and refueling.
Other studies in Europe have shown higher availability, especially
with the new offshore units.
This NREL report from 2000 shows downtime ranging from 43 hours to
127 hours per month (82% to 94% availability). See:
http://www.nrel.gov/docs/fy00osti/28620.pdf
Note that a lot of O&M downtime can be scheduled for times when the
weather report shows little or no wind is expected. An unplanned
equipment failure during high winds costs a lot of lost revenue, but
maintenance scheduled 3 days ahead of time for a calm period costs
nothing more than the labor and parts.
O&M costs are roughly 20 to 25% of the cost per KWH, so aggressive
steps are being taken to reduce O&M expenses, such as improved
computer monitoring of oil and bearing conditions.
In other wind news, Denmark is now generating 20% of its overall
power from wind. This was formerly thought to be the practical
limits, but improvements in the net have already been made, and they
have spurred new plans to generate 50% of electricity from wind by
2025. See: http://www.windpower.org/composite-520.htm
Overall Scandinavian wind power is expected to reach 17,000 MW
(nameplate), much of it offshore, or 6.5 GW actual. This is roughly
equivalent to 7.5 average U.S. nukes. The U.S. has about 100 nukes,
so this is very substantial generating capacity.
- Jed
