Juggling with power
Johannesburg, a world-class African city, has been hard hit by the recent spate of load shedding and has had to cut back on its bright lights.
Eskom's blackouts are taking a toll on Louis Pieterse, the man responsible for distributing the limited power the national power utility provides to City Power.
Johannesburg relies on Eskom for 90percent of its power, and the rest comes from the municipal Kelvin power station.
Pieterse must juggle the supply equitably between City Power's customers, who include businesses and millions of citizens.
He says other towns and cities are also affected by load shedding, but the consequences are more severe in Johannesburg because it is the country's economic heartland and home to many millions of people.
"The maximum demand for power in Johannesburg is equal to the demand in the city of Paris," Pieterse says.
"City Power provides businesses with 80percent of its power and the remaining 20percent goes to households."
Pieterse agrees that the city should communicate better with its customers, but says technical limi- tations prevent the city from providing a "cast-in-stone" schedule to customers.
Pieterse, the municipal electricity utility's operations manager, says his responsibilities extend across much of the metropolitan area, but exclude areas such as Soweto, Sandton and Orange Farm.
He has the almost impossible task of apportioning the limited power fairly and must ensure that everyone suffers equally.
City Power has developed a plan to shed power to each area for two hours at a time throughout the city. It uses a computerised system to switch off the power remotely, but the technology has introduced its own problems.
"Sometimes a switch in the system might not work and that forces people in the control room to turn off another area."
Fluctuating demand for power is another reason the city cannot publish a schedule for planned blackouts.
"We might announce that at such and such a time Midrand will be switched off, only to have demand being low at that time. In such a case we will not shed the load because there is a balance [on the supply system]."
Pieterse says load shedding is done to maintain a balance between the demand for and supply of power.
Certain areas will sometimes escape planned outages.
"But this does not mean we deliberately keep those areas switched on. It could be because of a technical fault or another cause, like a tree falling on power lines."
He says the public should understand that if the utility does not cut the power, then demand would exceed supply and the whole electricity network would collapse.
"Electricity is not like water. It cannot be stored. We are doing everything we can to ensure that we shed electricity equally between customers.
"When Eskom requests municipalities across the country to shed load, we shed almost 10percent of their [national] shortfall in Johannesburg because we use so much electricity. Other cities may only have to shed twopercent.
"For example, if Eskom has only 500MW to transmit, then we distribute 50MW of that," Pieterse says.