It is not yet clear how long Eskom’s embattled Duvha power station will be limping after “an apparent over pressurisation incident” rendered its unit 3 out of action on Monday night.
This is only the latest in a series of serious incidents at Duvha which raises questions about the quality of management at the power station.
This increased the utility’s unplanned outages by 600MW to 4 665MW and decreased an already very slim reserve margin further to 1 688MW. A further 5 624MW of generation capacity has been taken out of the system for planned maintenance.
The utility said in a statement on Monday night that there is however no immediate threat of load shedding.
It said: “After a boiler tube leak alarm, the boiler tripped on a high pressure alarm. Upon inspection, damage was observed in the boiler and surrounding equipment.
“The reason for the boiler over pressurisation is being investigated. Eskom engineers haven been on site today and have undertaken a preliminary assessment whilst the boiler cools down enough for a full assessment to be undertaken. The results of this assessment and the implications of this incident will be reported once available.”
Duvha Unit 4 was extensively damaged in February 2011, reportedly due to “operator error”. It was offline until January 2013, reducing available generating capacity by 600MW.
In February this year former Eskom CEO Brian Dames disclosed that the coal conveyor belt that transports coal from the adjacent mine to Duvha was damaged in December, resulting in significant coal supply challenges for the station.
This led to a reduction in output at Duvha. “Coal is temporarily being transported by trucks as a contingency,” Dames said at the time.
Moneyweb recently reported that the National Energy Regulator (Nersa) is very concerned about Eskom’s maintenance regime. Thembani Bukula, regulator member for electricity said the regulator is concerned about the quality of Eskom’s maintenance, since units taken out of service for major maintenance often break down again shortly after being brought online again.
Bukula criticised Eskom for doing extensive maintenance at all cost and improperly. The result is excessive unplanned outages that coincide with huge amounts of planned maintenance and insufficient generation capacity left to keep the lights on.
Shaun Nel, spokesperson of the Intensive Energy Users that represents Eskom’s biggest industrial customers says the organisation shares Nersa’s concern and there is clearly something wrong at Duvha. “Last year Duvah was shut down for ten days for maintenance, but it took much longer to bring it back to service again.”
He said unplanned outages are significant and it is clear that Eskom’s maintenance is not done properly or something is going wrong when it is brought back to service again.
The information Eskom supplies is usually at an aggregate level and the data for individual plants are not available. “The problems are at a level where it cannot be interrogated,” he said, calling for more transparency.