DUBAI, Dec 1 (Reuters) - World leaders are set to take the stage for a second day at the U.N. climate summit in Dubai on Saturday, as their governments lined up a slew of new pledges around green energy.

Among the headliners expected to speak at COP28 are U.S. Vice President Kamala Harris, Barbados Prime Minister Mia Mottley and Ukrainian President Volodymyr Zelenskiy, whose video address had originally been scheduled for Friday.

Governments also are poised to announce a promise to triple renewable energy capacity, boost nuclear energy capacity and rein in emissions of methane.

Friday's first day at the summit highlighted tensions between the United Nations, whose secretary general urged leaders to commit to quitting fossil fuels, and the COP28's UAE hosts, who have urged cooperation with oil companies.

Some leaders also used their podium time to criticize the war in Gaza.

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