President Joe Biden pledged on January 27 to conjure “a carbon pollution–free electricity sector” into existence “no later than 2035.” What would that involve? According to the Energy Information Administration (EIA), the U.S. electric power sector generated 4,127 terawatt-hours of electricity in 2019. Of that, 38.4 percent was produced from natural gas, 23.4 percent from coal, 19.6 percent from nuclear, 7.1 percent from wind, 7.0 percent from hydropower, 1.7 percent from solar power, and 2.8 percent from miscellaneous sources. How many power generation units does it take to generate that electricity? The country has 668 coal-fired units (producing 20.8 percent of America’s summer capacity), 6,020 gas-fired…