Renewables, not natural gas, were main driver behind drop in U.S. power sector emissions in 2017 -- ThinkProgress.org

The growth of clean energy in 2017 was one for the record books: Last year was the first time a reduction in U.S. power sector carbon emissions could be attributed more to renewable energy and energy conservation than the nation switching from coal to natural gas to generate electricity. ....
https://thinkprogress.org/carbon-emissions-decline-with-renewables/