050910 Electricity pylons carry power from Cape Town's Koeberg nuclear power plant July 17, 2009. South Africa will need 20 gigawatts (GW) of new power generation capacity by 2020 and would require double that amount a decade later to meet rising demand, the country's power utility said September 7, 2009. Picture taken July 17, 2009. REUTERS/Mike Hutchings (SOUTH AFRICA ENERGY BUSINESS)

South African power utility Eskom said on Monday that available spare supply on its electricity network had fallen to around 1 percent of total capacity after one nuclear unit was shut for maintenance and as industrial users ramped up demand.

In a bi-weekly status update, Eskom said it had 33,159 MW of capacity for the Monday evening peak hours, when people return home and turn on stoves and TVs, against forecast demand of 32,647 MW, leaving a buffer of just over 500 MW.

The available capacity includes gas-fired emergency reserves.

“The switch from higher winter tariffs to lower summer tariffs from Sept. 1 has seen higher demand from large customers, so that demand for electricity has not declined even though the weather has warmed up,” Eskom said in a statement.

The energy-intensive mining industry is among the sectors that pay higher rates during the three winter months from June until the end of August.

The utility said that some 1,739 MW were out due to planned maintenance work, while unplanned outages stood at 6,972 MW.

At one point in January the difference between peak demand and available capacity was a tiny 460 MW, mainly due to maintenance and unplanned outages, bringing Eskom closer to economically damaging rolling blackouts experienced in 2008.

Eskom is walking a tightrope to keep power flowing to factories, mines and smelters that had to shut for days four years ago, costing the economy billions of dollars in lost output. - Reuters