A cloud of methane was detected by satellite near coal mines in South Africa, drawing attention to a lesser-known environmental risk that comes from using the dirtiest fossil fuel. The potent greenhouse gas — methane traps roughly 84 times more heat than carbon dioxide in its first two decades in the atmosphere — was emitted at an estimated rate of 65 metric tons an hour on May 10, according to Kayrros SAS. The Paris-based analytics company found the leak by parsing European Space Agency satellite observations. It was the worst plume of methane Kayrros detected in the data over Africa this year. The cloud was spotted about 125 kilometers (78 miles) east of Johannesburg in an area where Sasol Ltd. has several coal mines as well as chemical and fuel operations. Sasol said it didn’t record any elevated methane levels that day and that emissions from its mining operations […]