''Energy markets are about to experience a seismic shift,'' Christopher Flavin, president of the Washington, D.C.-based Worldwatch Institute, said in a speech to oil executives and energy ministers in Johannesburg, South Africa, site of the 18th World Petroleum Congress.

''The question for oil executives is whether you're in the oil business or the energy business.''

The conference's 5,000 participants included ExxonMobil President Rex Tillerson and Saudi Arabian Oil Minister Ali Al-Naimi, Worldwatch said.