A study by the department of energy and National Treasury on a funding model for the planned nuclear expansion programme handed to Cabinet in 2015 advised that the best way to test cost analysis was to go to the market for tenders, the department told MPs on Wednesday.

Deputy director general: energy programmes and projects Zizamele Mbambo told Parliament’s portfolio committee the conclusion of the study, outsourced to Deloitte, was that “to get reliable information there is a need to go to the market”.

Mbambo was part of departmental team briefing the committee after it demanded insight into the various studies that had informed the government’s energy policy, updated in the draft Integrated Energy Plan and draft Integrated Resource Plan released by Energy Minister Tina Joemat-Pettersson last week.

The base case scenario outlined in the IRP sees South Africa needing to add 1 359 MW of new nuclear energy to the grid in 2037, increasing to 20 385 MW in 2050.

It uses a cost assumption of R5 400/kW.

However, Eskom immediately signalled after the minister released the energy blueprint documents that it would proceed with plans to issue a request for proposals by the end of the year.

And Eskom’s chief executive for generation, Matshela Koko, said if certain variables interfered with the base case scenario the country could still need to bring additional nuclear power online as early as 2025.

Mbambo briefed MPs on the broad findings of 16 studies conducted since 2008 when, faced with an energy crisis, government turned to nuclear expansion as a potential long-term solution.

He said the long-held view that the country needed to add 9 600 MW of new nuclear energy to the grid by 2030 came out of a 2013 study by local engineering consultancy Ingerop, chosen to provide an alternative to “western” data from the California-based Electric Power Research Institute.

Mbambo said the department had been reluctant to show its hand and release the findings of the various studies as it could skewer the procurement process by giving bidders insight into the state’s thinking.

“It impacts on the government’s bargaining position . . . It gives a comparative advantage to the prospective bidders in terms of understanding what is in the government’s mind. We would have wished that this be discussed in a more confidential manner so that it then protects that bargaining advantage for government later when it comes to procurement,” he said.