Moneyweb has obtained exclusive pictures of mountains of ash that have brought three units of Eskom’s Lethabo power station to a standstill.
This has deprived the national system of 1 854MW of power generation.
Eskom has announced load shedding on Saturday and Sunday, saying it is necessary to build up water reserves for its two pumped storage units that use water to generate electricity and to preserve diesel used in its open-cycle gas turbines. The utility further stated that the capacity normally imported from Cahora Bassa in Mozambique will not be available on Sunday due to maintenance.
Eskom normally gets a maximum of 1 500MW from Cahora Bassa and it is clear the Lethabo’s 1 854MW could have made a huge difference in keeping the country’s lights on.
Eskom spokesperson Tony Stott said it may have contained load shedding to phase one which means the demand has to be reduced by 1 000MW, instead of phase two (2 000MW) that has become imperative to protect the power system from a complete blackout.
The pictures show literally mountains of ash underneath some of the boilers at Lethaba, the power station situated between Vereeniging and Sasolburg in the Free State.
Stott explained that as coal burns in the boilers, heavy ash particles settle at the bottom of the boiler. These are being sucked out by hopper units and transported by conveyor belt to the ash stacker.
Sources at Lethabo have told Moneyweb the blocked hoppers were the source of the problem, stating that management has not heeded warnings and neglected maintenance.
Stott said the coal used at Lethabo has a high ash content. The power station has been run very hard and maintenance has previously been deferred. The current problems however go beyond normal wear and tear and were triggered by lightning hitting the stack last week, causing a build-up of ash backwards in the system and the hoppers filled up and overflowed, he said.
Workers at Lethabo are working around the clock to clear the ash by truck, he says. The utility is hoping to get one of the units back online over the weekend and the other two by Monday.
He confirmed that some of the pipes may have to be replaced and it may take months to have the stacker and the rest of the system fully functional again.
The ash build-up at Lethabo comes as Eskom is still reeling from the collpase of one of its coal silos at its Majuba power station near Amersfoort in Mpumalanga. This has destroyed the coal feeder system and coal is temporarily being fed manually. The power station is functioning at about 70% of 3 843 MW capacity.
Unit 3 at its Duvha power station has been damaged in an incident in March and is not expected to be back online in the next two years, depriving the system of another 600MW.
According to Stott the current available generation capacity is about 32 000MW out of installed capacity of about 43 000MW.