3. POWER STATION AVAILABILTY
Australian power stations have achieved significant improvement in
their availability in recent years. The best publicly available data
is the summary provided by the ESAA (1998). In 1995/6 the average
availability factor (AF) for Australia was 89.1% while for 96/97 the AF
had improved to 90.9%. The forced outage factor (FOF) had reduced
from 3.0 to 1.7.
The most dramatic improvement in AF had occurred in Victoria where most of the generating capacity during this period had passed from public ownership to private ownership. Almost all states improved FOF as is shown on Table 3. The magnitude of these changes has to be considered. Total installed capacity in Australia in 1997 was 39.017 GW, so an improvement of 1.8% in AF is equivalent to having another 700 MW available in the system.
Another means of considering the importance of availability figures is to consider their value to the generator. Outages of power stations represent a major economic factor in their operation. Even at $20 per MWhr, a typical figure achieved in the current electricity spot market, a 500 MW power station can earn $240,000 per day. A loss of availability (LOA) of 1% of a 500 MW unit at these rates costs that company $876,600 per year.
3.1 International comparisons.
The performance of the Australian Power Stations is now extremely good
and can be compared internationally. One source of comparative data
is the North American Electricity Reliability Council (NERC). Some
recent data for large fossil fired units are shown on Figure 1. The
average of the 262 stations is 80.9% AF. This is well below the Australian
average of 90.9% in 96/7. The Australian average AF would appear
to be exceeded by only 3% of the US stations.