US President Donald Trump has stepped up his attacks on wind power, claiming turbines ruin property values, are a “graveyard” for birds and that their noise emissions cause cancer.

“If you have a windmill anywhere near your house, congratulations, your house just went down 75% in value. And they say the noise causes cancer,” he said during a National Republican Congressional Committee dinner on Tuesday.

“And of course, it’s like a graveyard for birds. If you love birds, you’d never want to walk under a windmill, because it’s a very sad, sad sight. It’s like a cemetery. We put a little statue for the poor birds,” he added.

His comments were part of an attack against Hillary Clinton, who he defeated in the November 2016 presidential election. Clinton, a Democrat, strongly advocated continuing federal subsidy support for wind energy and other renewables as part of US efforts to combat global warming, which Trump doesn’t acknowledge.

Trump offered no evidence to support his assertions which wind industry officials have said are exaggerated, inaccurate or misleading.

US Senator Charles Grassley, an Iowa Republican who was the driving legislative force behind passage of the federal wind production tax credit law in 1992, said the president's claim that turbines cause cancer was "idiotic" and had no factual basis.

While an outspoken supporter of fossil fuels, particularly coal, Trump has been more vocal against US onshore wind power since progressive-left Democrats in February released their Green New Deal proposal to mobilise America to achieve net-zero greenhouse gas emissions and a carbon-free grid within a decade.

He has repeatedly mocked the Green New Deal as the “craziest thing,” imploring Democrats to let him run against it in 2020 national elections. “If they beat me with the Green New Deal, I deserve to lose,” he said Tuesday.

At a Michigan campaign rally last month, for example, he slammed wind power as unreliable because it is intermittent.

“If it doesn’t blow, you can forget about television for that night,” he said, asserting, “I know a lot about wind.”

Trump’ animus toward wind was also stoked by a losing legal battle his International Golf Club waged in Scotland challenging consent for an 11-turbine project in Aberdeen Bay. The club, which must pay the Scottish government’s legal costs, claimed the project would ruin the views of golfers playing at the luxury resort.

US wind power capacity totaled 96.5GW on 1 January with all but 30MW onshore. It generates about 7.5% of the country's electricity.

Oddly, Trump supports offshore wind as a critical element to help the US attain energy dominance.

By that, he means his geopolitical strategy for achieving self-sufficiency in energy and to maximise the economic and technological benefits of doing so, while having ample surplus for export to friendly nations facing supply uncertainties – particularly from Russia and the Middle East.

Thus, even as he publicly demeans onshore wind turbines, his administration is pushing hard to lease zones for offshore development along the east coast – if the turbines are not visible from shore.

That has left Democrats and environmentalists supporting his offshore wind aspirations even as they disparage Trump for his criticism of other clean energy and climate change.