They did not include any numbers on wind, solar, hydro, tide, ... renewable energy; limiting the comparison to "the dominant" energy sources what they call "all major energy sources" shows how narrow the researchers' plate is.

World hydro power generation has already a greater percentage than nuclear fission, not in the U.S. though.. Add other renewable resources and all renewable surpass gas. Oil plays almost no role in energy generation. See https://en.wikipedia.org/wiki/Electricity_generation#Methods...