Johannesburg, South Africa -- Johannesburg Water SOC Ltd., which provides sanitation to South Africa’s biggest city, plans to expand power capacity from a biogas plant almost fourfold, cutting reliance on electricity from the state utility.

The combined heat and power generation plant at the Northern waste water treatment works uses sewage sludge and has 1.2 megawatts of generation capacity, reducing Johannesburg Water’s need for power from provider Eskom Holdings SOC Ltd. by 15 percent, Karl Juncker, managing director of WEC Projects (Pty) Ltd., which designed and built the plant, told reporters in the city yesterday.

“We plan to build more plants and expand to about 4.5 megawatts in the next four to five years,” which could cut Johannesburg Water’s electricity requirement from Eskom by as much as 60 percent, Junker said. One megawatt is enough to power about 500 to 1,000 U.S. homes.

South Africa, where chronic electricity shortages led to the suspension of mines and factories in 2008, has embarked on a program to boost generation by awarding contracts to build wind, solar and biomass plants. The renewable-energy drive is used to cut reliance on coal, which it uses for 80 percent of power generation.

The cost of the facility, which has been producing electricity for a year, and a second plant at the Driefontein water works is about 67 million rand ($7 million), WEC said in an e-mailed statement.

The cost of electricity that Johannesburg Water will need to run its six waste-treatment facilities will triple to more than 300 million rand annually in the next seven to 10 years from about 95 million a year now, Peter Louw, a project engineer for the utility, said in the statement. The six plants have the potential to produce 8.5 megawatts of power, he said.

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