President and part-time coal miner Donald Trump Photo: Mark Lyons/Getty Images

Last week, President Trump used his Twitter account to make what was, especially for him, a curiously specific plea for the Tennessee Valley Authority to keep open a coal-fired power plant it was proposing to close.

Coal is an important part of our electricity generation mix and @TVAnews should give serious consideration to all factors before voting to close viable power plants, like Paradise #3 in Kentucky! — Donald J. Trump (@realDonaldTrump) February 11, 2019

The tweet was in vain. Thursday, the TVA announced it is closing Paradise No. 3, along with another aging coal plant. It was another manifestation of Trump’s impotence at achieving what was, to some of his most important constituents, a key campaign promise.

The revival of coal is a key tenet of Trump’s platform, and one he has taken pains in the past to present as having accomplished. “Trumponomics,” a hilariously clumsy and sycophantic paean to the administration’s economic agenda in general and the brilliance of the president in particular, contains a passage praising Trump for reviving coal. “One theme of this book is that Donald Trump has a talent for proving his critics wrong,” the authors Stephen Moore and Arthur Laffer note, citing him for engineering a “the coal industry comeback” that critics insisted could never happen.

The book mockingly quotes former Obama adviser Jason Bordoff, who predicted, “Scrapping the Clean Power Plan may slow the decline of coal — but it’s not bringing coal back.” Moore and Laffer retort in the book, “Well, coal and mining are back.”

Actually, they are not. Coal plants have continued to close at a rapid pace under Trump. Coal mining jobs have plateaued:

Meanwhile, the official government agency that forecasts energy trends predicts coal use will now fall below the levels that had been projected if the Clean Power Plan had remained in place:

Trump’s idea was that, by allowing coal companies to emit more pollutants into the atmosphere, he would lower their operating costs enough that they could stay in business or, ideally, expand their market share. It simply hasn’t worked. The cost of wind and solar energy is dropping so fast that even dirtier coal plants can’t compete on a cost basis. It’s actually less expensive to build a new wind or solar plant than to keep running an existing coal plant.

One sign of helplessness came in a subtle omission in the president’s State of the Union address. The 2018 speech boasted, “we have ended the war on clean coal!” This year’s speech touted other energy sources (“the United States is now the No. 1 producer of oil and natural gas in the world”) but made no mention of coal at all.

It was perhaps the most pathetic sign of Trump’s feebleness that he could not even coax the TVA, a government-controlled agency located in the heart of Trump-coal country, to keep open its coal plants. Trump does not directly control the TVA’s entire board, but surely if he had any case to make for coal, any lifeline to offer, it would have been taken here. Instead the agency simply noted that coal was no longer cost-effective. “It is not about coal. This decision is about economics,” TVA chief executive William D. Johnson said. “It’s about keeping rates as low as feasible.” People aren’t willing to pay higher electric bills for the privilege of dirtier air.

Trump’s floundering efforts to do something that he can sell as a “wall” that he “built” have captured the headlines. But to many of his voters, the promise that mattered was to bring back coal. And he can’t even pretend to have done it.