Both Eskom CEO Brian Dames and public enterprises minister Malusi Gigaba may have shied away from saying that load shedding is on its way, but analysts and people working in the industry believe it is a very real possibility, given that our electricity system is running with almost no reserves.

In a quarterly state-of-the-system briefing, given in Johannesburg and then again in parliament earlier this week, Eskom revealed just how tight things have become for the country.

The week began on a reserve margin of 881MW — or just under 3%. This almost nonexistent breathing room for the country’s power system has become a common occurrence in recent months.

On 22 April, a unit at Koeberg was returned to service, adding 900MW to the grid.

The power line that transports electricity from Cahora Bassa in Mozambique to South Africa is expected to be back up and running by the end of April, adding another 600MW. The 1 500MW supply from Cahora Bassa has been patchy since the middle of last year after a technical failure at a substation in Mozambique. This was followed by the transmission line going down due to floods in January.

To cope with these supply problems Eskom has, for some months, been holding off on the maintenance it normally does in summer and has run its diesel-fuelled peaking power plants at the highest rates seen in the past four years to keep the lights on.

But Dames made it clear that it can no longer defer this maintenance because a number of power stations have reached their technical limits and the longer maintenance is put off the more unreliable plants become, and the greater the risk of unplanned outages.

These problems were widely foreseen as far back as 2010, when the integrated resource plan — South Africa’s 20-year electricity road map — was drafted. Alongside the plan, the department of energy released a medium-term risk mitigation report. It said that until Eskom’s new power stations, Medupi and Kusile, were up and running, South Africa faced continued power shortages until 2016. The strain this would place on Eskom’s existing plants and the effect it would have on Eskom’s ability to perform maintenance was of particular concern.

Important measures to mitigate against these power shortages included the roll-out of a million solar water heaters to households, and bringing in non-Eskom-generated power in the form of renewable, own-generated and co-generated power.

The solar water heater target has been missed and although ambitious work has been done to bring renewable independent power producers on to the grid, it has not happened at nearly the pace needed to meet the supply shortages.

To add to these woes, it is unlikely that Medupi will come online before December thanks to recent labour troubles and major performance problems with contractors such as Hitachi Power Africa.

Nomura analyst Peter Attard Montalto estimated that Medupi might only provide its first power to the grid as late as March 2014 — a delay that both Eskom and Gigaba have promised will not happen.

In the meantime, South Africans face a winter of discontent. Given the extraordinary tightness of the system, “if anything unforeseen happens, there is no margin”, heightening the risk of load shedding, said Oliver Stotko, principal environmental engineer at energy services company Carbon & Energy Africa.

The morning and evening peak hours are of particular concern to Eskom. It has appealed to residential customers to curb their usage at these hours and switch off all geysers, pool pumps and nonessential appliances to reduce demand during this critical period.

Residential and municipal customers have contributed the most to a reduction in demand. According to Eskom, municipal and residential customers are expected to save 59% of the projected demand savings for the 2013 financial year.

Dames told the Mail & Guardian that many large industrial customers have voluntarily shaved off as much as 10% of their demand, but there is more that can be done. He estimated that industry could save between 25% and 35% more power.

Eskom reiterated its call this week for the government to institute a mandatory power conservation programme.

But Mike Rossouw, who chairs the Energy Intensive User Group of Southern Africa, said that the body believed a “mutually beneficial solution” could be reached without implementing a mandatory scheme.

Many large users had voluntarily signed on to save demand by at least 10%. To introduce a mandatory scheme would require large users to come in at even lower levels, he said.

There were measures available to Eskom to prevent load shedding and large industry had been working with the power utility to mitigate the risk, said Rossouw.

Unless there was a concerted “coming to the party” by domestic users, load shedding is highly likely, said Chris Yelland, electricity pundit and MD of EE Publishers.

Eskom is already effectively load shedding by exercising its interruptability clauses with aluminium smelters. These clauses allow it to cut supply to the smelters for two hours a week. Eskom is also paying large industrial customers to cut electricity consumption through its power buy-back programme, which has freed up 1 010MW for the electricity system. The programme is due to expire at the end of May, but Eskom is in the process of evaluating contract extensions.

The heightened use of Eskom’s peaking plant, which cost the utility roughly R2/kWh to R2,50/kWh to run, was a sign that “its cupboard is bare”, said Yelland.

He said there are few incentives for residential customers to reduce their demand during peak hours, other than inconvenience.

Eskom should implement time-of-use tariffs for residential customers, he said. This would make electricity more expensive during certain hours of the day. These tariffs are already in place for industrial customers. “If residential customers knew that using electricity during peak hours would be three times more expensive there would be a financial incentive to cut back,” said Yelland.

Load shedding that was done systematically and managed well would “not be the end of the world”, said Yelland, because it might make consumers realise the importance of conserving power during peak periods. According to Eskom, load shedding could be avoided if 4m households switched off their geysers between 5pm and 9pm. This would create an additional 2 000MW during the periods of highest demand.

There are ways for homes and businesses to conserve energy and reduce the risk of load shedding, said Oliver Stotko, principal environmental engineer at energy services company Carbon & Energy Africa. Some cost money but others are as simple as switching off unwanted appliances. Converting to cooking on gas is one way to reduce electricity demand, with the added advantage that if the lights do go out, hot meals will not be off the menu.

Solar water heaters or heat pumps can replace geysers for roughly R15 000. The pay-off period for this type of investment is typically eight to 10 years.

Alternatively, insulating a geyser can conserve energy. The typical geyser draws electricity just to keep water at a set temperature, even if water is not being drawn from the geyser, said Stotko.

Efficient lighting systems can also make a difference. Lighting systems that optimise the use of daylight, requiring as little artificial light as possible, can be installed.