Reuters: The Gulf Arab emirate of Abu Dhabi said on Monday it will invest $15 billion in the first phase of an initiative by the oil-exporter to develop green energy. The investment would be made as part of the Masdar initiative to develop sustainable and clean energy, Abu Dhabi’s Crown Prince Sheikh Mohammed bin Zayed al-Nahayan told the World Future Energy Summit in the emirate. Sheikh Mohammed did not give a time frame for the investment in Abu Dhabi, one of seven members of the …