South Africa’s electricity crisis is costing the economy as much as R899 million a day, according to central bank estimates. Rolling blackouts of about 6 to 12 hours a day, or so-called Stage 3 and Stage 6 outages, detract between R204-million and R899 million from the economy daily, the South African Reserve Bank said in an emailed response to questions on Monday. Power cuts, known locally as load shedding, are needed to protect the grid from collapse when state-owned company Eskom Holdings SOC Ltd.’s aging and poorly maintained and mostly coal-fed plants can’t meet demand.