President Donald Trump apparently knows exactly what’s wrong with wind power. Wind power won’t work because wind “only blows sometimes,” he explained to Sean Hannity on Fox News .

The president still believes that wind power is not a viable energy source because "it only blows sometimes" pic.twitter.com/UgTzygyN35

Trump also insisted Thursday evening at a rally in Michigan that he “knows a lot about wind. If it doesn’t blow, you can forget about television for that night,” he said.

Wind energy can be stored in a variety of ways, including in something called batteries. Most power grids combine energy provided by different sources — as the Trump administration’s own Energy Department explains on its website for anyone who cares to look. “The wind does not always blow and the sun doesn’t always shine,” the site helpfully notes. Yet the power grid “can accommodate large penetrations of variable renewable power without sacrificing reliability.”

Trump shared his energy insights during a rambling, often repeated point that he is the toughest president ever on Russia. That apparently has resulted in a boost in U.S. fossil fuel use and sales, he said in the Wednesday phone interview with Hannity.

“It’s what we have done with energy and oil and gas. That’s all competition from, for Russia,” Trump said. “You look at the Ukraine. You look at so many different levels. You look at our military,” he added.

“You look at the fact that we would have been powered by wind, which wouldn’t have worked, by the way, because it only blows sometimes and lots of problems come about.”

He made a similar observation last week about wind energy in Ohio, which caused one energy expert to call him a “clown.”

Trump complained to workers at a tank factory in Lima that his former Democratic rival Hillary Clinton “wanted to put up windmills everywhere.” He then pretended to be some anonymous husband, telling his wife: “Turn off the television darling, please. There’s no wind. Please turn off the television quickly.”

Michael Mann, a professor of atmospheric science at Pennsylvania State University, told Newsweek after the president’s remarks then: “Trump is a clown, but a dangerous, evil clown. He would happily mortgage the future of our children and grandchildren for the short-term profit of the fossil fuel interests whose bidding he’s doing.”

Trump repeated his television routine Thursday in Michigan.