How Trump’s order to have the military buy coal would actually work

President Donald Trump says the military will start "buying a lot of coal" as part of a new push to boost domestic coal production and strengthen what he describes as the reliability of the U.S. power grid. Turning that pledge into reality, however, will require navigating Pentagon procurement rules, congressional funding limits and the physical constraints of the electric grid.

A new executive order, signed Wednesday, directs the secretary of war to "seek to procure" power from coal-fired...