Johannesburg - South Africa’s power supply is likely to remain tight for the next five years, with 2011 and 2012 being particularly constrained until new plants come on line, power utility Eskom said on Friday. Eskom supplies the majority of electricity to South Africa but has been struggling to meet fast-rising demand. It has said before that supply will remain tight until 2015, when two new power plants come on stream. The utility said peak demand this winter would be likely to hit 37 000 megawatts (MW), virtually unchanged from last year’s highest load of 36 970 MW. CEO Brian Dames told a news conference electricity demand in the first quarter was up 1.5% compared to 2010, but lower than an earlier estimate of 2%. Overall demand is now at the same level as 2007, before South Africa slumped into its first recession in nearly two decades, Dames said. The first of six units of South Africa’s 4 788 MW Medupi power plant - Eskom’s first new power plant in over two decades - should come on stream in late 2012, and the first unit of the 4 800 MW Kusile plant should be operational in late 2014. Eskom also said on Friday it had no plans for a new foreign bond issue at present.Dames said the company was happy with the results of the previous issue. Eskom earlier this year raised $1.75bn from a 10-year international bond issue.