Electricity utility Eskom and the Chamber of Mines (CoM) are in talks about urgently replenishing stockpiles of coarse coal at its power stations, as these stocks have been depleted over the past two weeks as much of the country has experienced a protracted period of wet weather.
On March 6, the utility resorted to 14 hours of load shedding for the first time since early 2008 to prevent a system collapse, after it lost four units, or over 3 000 MW, at Kendal, in Mpumalanga, the largest power station in its 40 000-MW-plus fleet.
The units were switched off after wet, fine coal clogged the logistics system linking Kendal to BHP Billiton’s Khutala colliery, effectively stranding the units from their fuel source – Kendal burns about 50 000 t of coal daily, of which 40 000 t is supplied fresh from the mine.
This material loss of load, together with problems at Duvha and Majuba, as well as more generalised load losses associated with wet, fine coal at Eskom’s other power stations forced Eskom to declare a power emergency at 6:00 on Thursday morning and to begin implementing load shedding from 8:00.
Eskom CEO Brian Dames has requested a comprehensive report on the coal-supply breakdown from both the Kendal and Khutala management teams, having visited Kendal and Khutala together with Public Enterprises Minister Malusi Gigaba on March 10.
The disruption reportedly coincided with a shift change at the underground portion of the mine, which was supplying Kendal with coarser and drier material. Wet coal in itself is not regarded as a problem. But fine, wet coal is problematic, with Kendal typically requiring that coarse coal comprises between 60% and 70% of what it burns.
When the supply of coarse coal from the underground mine stopped, Khutala reportedly supplemented it with wet, fine material from the opencast operation, without communicating the change. This slurry-like material clogged the conveyors and material-handling systems and between 1:22 and 7:58 on March 6 four units tripped, owing to empty coal bunkers. This, despite Kendal having more than 56 days of stocks, covering an area the size of four rugby fields.
It took most of Thursday for Kendal’s employees to clear the blockages and, using material from the stockpiles, blended with underground coal and some heavy-fuel oil, all of the station’s units were back online by 17:26.
Eskom was able to lift the emergency and end the load-shedding episode, which led to business closures, disrupted mobile networks and resulted in widespread traffic congestion.
Speaking at a briefing hosted by the South Africa Chamber of Commerce and Industry on Tuesday, Dames said he wanted to see five-days-worth of coarse-dry stocks replenished across the fleet. He said he had personally insisted on the creation of such stockpiles following the events of 2008, which had led many of the power stations to dub them as ‘Brian’s stockpile’.
But an immediate replenishment could be difficult and costly to rebuild, particularly in light of the ongoing inclement weather.
Therefore, Dames met with the CoM on March 10 to request whether it could help Eskom source coarse coal for its stations, at a price that was affordable – in other words, not offered at an export parity price.
In parallel, Eskom is also reviewing the communications between the tied collieries and its power stations to “improve line of sight”, especially between the general managers of Khutala and Kendal.
However, Dames says risks are even higher at other stations, referring specifically to Duvha, were logistics have been strained since a December conveyor fire.
He again cautioned the system remained at risk of again descending into an emergency, particularly in light of its large-scale summer maintenance programme, which meant that as much as 6 500 MW could be down for planned maintenance at any one point.