The announcement comes at a price. Of all fossil fuels, coal emits the most carbon dioxide per unit of energy, and burning it releases deadly pollution into the air. Research from the energy consulting group Grid Strategies also found that the Trump Administration’s push to keep coal plants open could cost U.S. utility customers between $3-6 billion by the end of 2028. That’s because coal is also among the most costly power sources. In the U.S., 99% of coal plants are more expensive to run than it would be to replace them with wind or solar.