As South African coal workers walked off the job this weekend to demand higher wages, power utility Eskom said on Monday that it had contingency plans in place, but that a protracted strike could risk power supply.

Wage negotiations in the coal sector reached a deadlock last week, as employers placed an 8.5% offer on the table, while the National Union of Mineworkers (NUM) demanded a 14% increase and Solidarity a 12% pay rise.

Eskom has coal stockpiles for an average of 38 days, but spokesperson Tony Stott said the utility remained concerned.

“We have stockpiles and open cycle gas turbines with the capacity of about 2 400 MW. Further, we have contracts with large customers, who might voluntary reduce electricity during periods of increased demand, or we can interrupt supply.”

But, the longer the strike continues, the more challenging and the higher the risk to Eskom’s contingency plans, Stott said.

“We would not like stockpiles to be depleted completely, in light of challenges experienced in 2008 with regard to coal supply and the wet season. We would have liked to use stockpiles at a much slower rate,” he told Engineering News Online.

Further, Eskom was also concerned by the capability of mines to produce the required coal at the pace required before the summer season, once the strike is over. “The coal mines will have to produce the coal required daily and additional coal to make up stockpiles for 38 to 40 days,” he explained.

Given the country’s tight power system, concerns regarding supply remain significant, not withstanding the effects on the economy.

To mitigate the effects of the strike, Stott said it was also key for all South Africans to continue not to waste, and where possible reduce the use of electricity.

Meanwhile, Chamber of Mines (CoM) spokesperson Jabu Maphalala told Engineering News Online that the chamber has not received feedback from coal mining companies, Anglo American Thermal Coal, Delmas Coal, Exxaro Coal Mpumalanga, Kangra Coal, Optimum Coal and Xstrata Coal, with regard to operational impacts since Sunday.

The CoM said unions jointly submitted more than 50 demands, but declared a dispute after only two negotiating sessions and deadlocked after a single meeting under the auspices of the Commission for Conciliation, Mediation and Arbitration. “The negotiations were thus not given a fair chance to succeed,” said Dr Frans Barker, who is negotiating on behalf of the coal mining companies.

NUM spokesperson Lesiba Seshoka said the union’s doors remained opened for talks with the CoM once the coal miners were prepared to meet the unions’ demands, but until then, some 150 000 workers would continue with the strike.

Solidarity said executive officers who received up to 93% increases and employers who did not "put their words regarding skills retention into action", had compelled it to issue a strike certificate to employers.

Deputy general secretary Dirk Hermann said when executive officers received increases yearly, it created an expectation with employees that they would receive similar increases.

Solidarity has 11 unsolved issues with the CoM, including payment for overtime work done on Sundays and public holidays, housing allowances and family responsibility leave.

Meanwhile, the United Association of South Africa (Uasa), said its members working at the Goedehoop, Klein Koppie, New Denmark and the Isobonelo operations were on strike from Sunday, with members employed at Anglo American Thermal Coal to down tools from Monday. The union is seeking a 14% increase in salary for its members.

"There is a strong indication from workers at several Xstrata mines that they will join the strike on July 28, if salary demands are not met," the union said.