President Donald Trump renewed his long-standing attacks on wind energy when addressing the pro-Trump student organization Turning Point USA on Saturday.

"I know windmills very much," he said, adding that he had "studied it better than anybody I know."

Trump said windmills were "noisy" and "kill the birds," and he complained about "fumes" he said they gave off, describing himself as an "environmentalist."

Trump has long criticized renewable-energy forms and has falsely claimed that wind farms cause cancer. He also actively campaigned unsuccessfully against a wind farm near his Scottish golf course in Scotland.

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US President Donald Trump ranted about wind energy in a speech to a conservative youth group, saying he had "studied it better than anybody."

In a speech to the pro-Trump student organization Turning Point USA on Saturday, Trump turned to berating windmills after criticizing the Green New Deal — the proposal by left-leaning Democrats to address climate change and inequality in the US.

Trump argued that windmills were "noisy" and "kill the birds," and he was critical of the fact that many were built outside the US as he repeated his long-standing distaste for the renewable-energy source.

"I never understood wind. You know, I know windmills very much. I've studied it better than anybody I know. It's very expensive. They're made in China and Germany mostly — very few made here, almost none," he said.

Trump also criticized the manufacturing process of the wind turbines as creating "fumes":

"But they're manufactured tremendous — if you're into this — tremendous fumes. Gases are spewing into the atmosphere. You know we have a world, right? So the world is tiny compared to the universe. So tremendous, tremendous amount of fumes and everything. You talk about the carbon footprint — fumes are spewing into the air. Right? Spewing. Whether it's in China, Germany, it's going into the air. It's our air, their air, everything — right?"

The American Wind Energy Association has found that while carbon emissions are created from windmill construction, most wind-power projects repay their own carbon footprints within six months of starting operations.

Wind turbines at a wind farm on January 21, 2016, in Colorado City, Texas. Spencer Platt/Getty Images

A gas called sulfur hexafluoride, or SF6, is often used in projects like wind turbines to stop electrical accidents and fires. Though the gas is "the most powerful greenhouse gas known to humanity," according to the BBC, concentrations of it in the atmosphere are very small.

Trump also described them as an issue for anyone living near them: "And if you own a house within vision of some of these monsters, your house is worth 50% of the price. They're noisy."

Much of Trump's lecture about the wind turbines, however, focused on their effects on birds. "They kill the birds," he said. "You want to see a bird graveyard? You just go. Take a look. A bird graveyard. Go under a windmill someday. You'll see more birds than you've ever seen ever in your life.

"You know, in California, they were killing the bald eagle. If you shoot a bald eagle, they want to put you in jail for 10 years. A windmill will kill many bald eagles. It's true."

A bald eagle, a type of bird Trump said were frequently killed by wind turbines. REUTERS/Chris Helgren

Trump later said of bald eagles: "If you killed one, they put you in jail. That's OK. But why is it OK for these windmills to destroy the bird population? And that's what they're doing."

While birds are killed by flying into wind turbines, many more are killed by flying into things like cellphone and radio towers — or in encounters with cats.

One audience then replied "Because they're idiots!" according to the official White House transcript.

Trump then laughed, and said: "This is a conservative group, Dan. No, but it's true. Am I right?"

Trump said that he thought windmills were "OK in industrial areas" and that he liked "all forms of energy."

But he said one of his issues was with their appearance. "I've seen the most beautiful fields, farms, fields — most gorgeous things you've ever seen, and then you have these ugly things going up," he said.

Among Trump's grievances were the fact that different companies make them, meaning they may not all match in appearance and the idea that "after 10 years, they look like hell."

Trump at his Scottish golf course, where he campaigned against the installation of wind turbines nearby. REUTERS/Carlo Allegri.

Though Trump called himself an "environmentalist" during the speech, he has repeatedly criticized renewable-energy forms and has taken actions considered harmful to the environment including taking the US out of the Paris climate agreement.

On wind energy, Trump has previously falsely claimed that wind farms cause cancer — a theory rejected by scientists.

He actively but unsuccessfully campaigned against the construction of a wind farm near his golf course in Scotland, even running TV ads about the topic.