Joel Avni and Kamogelo Seekoei

Blame Eskom's power outages this year on the weather gods, helped by irregular coal supplies and ageing generation stations that could not keep up with the impossible demands placed on them.

But rainfall 40percent above the norm set off the load shedding spiral, the utility's spokesman, Andrew Etzinger, said yesterday.

Most of South Africa's electricity is generated by 10 ancient coal-fired plants, principally scattered around mines in Mpumalanga and Limpopo.

The country is blessed with so much coal that South Africa's energy reserves rival those of Saudi Arabia. But it is cursed because much of this coal is of such low quality that it poisons the land around which it is consumed and the atmosphere much further away.

So few people want it and it cannot be exported in these days of global warming and heightened environmental sensibilities.

No matter, said the apartheid regime's eminently practical planners. We'll export whatever high-grade coal we mine and produce the cheapest electricity in the world with the ample supply of low-grade fuel. These environmentally inefficient plants are the backbone of South Africa's power-generating system and are built on, or near the coal mines that fuel them.

Their creaky infrastructure has been patched and modified over the years, but they groan on regardless and still power Africa's most dynamic economy.

Ignoring the small issue of poisoned people and countryside, they work. But not in the rain.

The copious downpours in the Mpumalanga area over the past few months have brought one plant after another to its knees. A slurry of coal dust and rain has gummed up the works, blitzed efficiency and even stopped some plants from operating altogether.

More than 25percent of the utility's generating capacity has been knocked offline.

Eskom tries to keep a 15percent reserve capacity available for unexpected demands and to compensate for units that are knocked offline at its ageing power stations. But a combination of rocketing demand and stations gunked up by goo threw its calculations for a loop this summer.

The problems with wet coal and ageing plant were compounded by an inadequate stock of coal at plants forced to work overtime to make up the deficit.

Eskom tries to maintain a 20-day stockpile at its power stations. But this has been reduced to 10 days of fuel. And with rains still soaking its reserves, mines having to cut back production because of power cuts, recovering production lost in the Christmas break and more inclement weather predicted, there is no guarantee the situation will change any time soon.

The government has appointed a committee to propose ways to increase the supply and exports will be trimmed until the position stabilises.

The company expected a peak demand of 31500MW yesterday, about 2500MW short of its generating capacity if nothing else went for a loop.

Unplanned maintenance and the unexpectedly rapid depreciation of generating capacity at its plants blew Eskom's plans out the water. And with the rapidly rising demand from industry, business and households that won't change until 2016.

Modern power plants take eight to 10 years from planning to production

The previous regime built so many coal-fired, poison-belching plants that many were mothballed as white elephants in the 1980s and 1990s - fortunately. Three are being restored at a cost of billions of rands over a decade and will come on stream between now and 2011. But they are just a stopgap.

Two new coalfired plants are being built, at Medupi in Limpopo and Project Bravo in Mpumalanga. They will add nearly 9000MW to the grid by 2016.

But the real difference will only be felt once the four new nuclear stations Eskom plans start coming online in 2016. The utility has pegged its hopes on nukes and expects to produce 20000MW of electricity from them by 2025, a quarter of its expected capacity.