"During this time the Eskom board and Mr Dames will work together to ensure a smooth transition to a new chief executive."

Brian Dames has resigned as Eskom CEO, the power utility said on Thursday.

"Eskom will still have the benefit of his vast experience and knowledge until March 31, 2014," Eskom board chairman Zola Tsotsi said in a statement.

"During this time the Eskom board and Mr Dames will work together to ensure a smooth transition to a new chief executive."

The process to find a successor was well underway and was expected to be concluded timeously, Tsotsi said.

Dames has worked for Eskom for 26-years and was appointed chief executive on July 1, 2010.

Reflecting on his time at Eskom, Dames said in the statement he believed the power utility had improved the lives of the public.

"My tenure at Eskom has given me an opportunity to become part of the solution that our country needs to succeed.

"The significant improvement that we make in the lives of ordinary South Africans is one of the best barometers of our success as a company, and I am grateful to have played a role in changing people's lives for the better."

He thanked the Eskom staff, its board, and shareholders for their support.

Public Enterprises Minister Malusi Gigaba commended Dames for leading Eskom's build programme.

"The minister commends him for putting the foundation of the build programme in place, where the three power stations, Medupi, Kusile, and Ingula are already at advanced stages of construction," Gigaba's office said in a statement.

"Mr Dames steered the company meticulously, with integrity. Despite the many challenges, he managed to keep the company stable."

Earlier on Thursday, Eskom spokesman Andrew Etzinger said the parastatal might need to bring in another company to install software for the Medupi power plant's boilers if French multi-national Alstom failed to do this in time.

"We have a contingency plan in place in case Alstom is not able to meet any of its milestones."

Etzinger said Eskom would not cancel its contract with Alstom, but would rather consider bringing in another company to work alongside it.

In October, Eskom said South Africa could expect electricity from the coal-fired power station Medupi in Lephalale, Limpopo in 2014.

The first of six 794MW units at Medupi would produce electricity in the second half of 2014.

The rest of the units in the new power stations would go online at eight-month intervals until completion in 2018, the company said at the time.

Etzinger said on Thursday that progress at Medupi was still going well.

On Wednesday, he said Eskom was seeking an environmental licence that would allow its Kriel power station, in Mpumalanga, to keep running.

The station has been operating outside its licensing conditions because the emissions do not comply with environmental regulations. That forced the power utility to apply for special permission to continue operating.

"If we don't receive relaxation, tough decisions would have to be made, and it would be a challenge that would put Eskom under severe pressure," Etzinger said.

The current licence expires on December 31.

Environmental affairs department spokesman Albi Modise said industries such as Eskom, holding Atmospheric Pollution Prevention Act licences, were required to apply to convert these to atmospheric emission licences by March 2013.

Eskom had raised concerns about being unable to comply with the provisions of its atmospheric emission licenses for the Duvha, Kriel, and Matla power stations.

Modise said Eskom had been advised that it could apply for a five-year postponement of the time-frame for compliance through the environmental affairs department's national air quality officer.