President Donald Trump is ratcheting up criticism of wind and solar projects he says are a "blight", adding uncertainty for investors deciding which projects can still move forward despite the coming end to most of the industry's clean energy tax credits.

Trump mounted one of his most expansive attacks yet on the renewable sector last week. For years, Trump has detailed his disgust for wind farms he sees as unsightly and too expensive, whereas he said he was a "big fan of solar" in last year's presidential debate. But Trump's perspective appears to have shifted. He now believes large solar projects are hated by farmers, "very, very inefficient and very ugly too", and should no longer be built.

"We don't want wind, and we don't want solar, because they're a blight on our country," Trump said during a cabinet meeting on 8 July. "They hurt our country very badly."

That stance offers another troubling sign for investors in wind and solar projects hoping to qualify for the 45Y and 48E clean energy tax credits before they are terminated under Trump's recently signed tax and energy law. Trump already signed an executive order last week seeking a "strict" interpretation of the end of those tax credits, such that fewer projects will meet a safe harbor deadline that will arrive as soon as 31 December.

The administration has other potential tools to undermine wind and solar projects, many of which are depending on new electric transmission lines to connect to load centers. Last week, US senator Josh Hawley (R-Arkansas) said he had received assurances from US energy secretary Chris Wright that the administration would be "putting a stop" to the 800-mile Grain Belt Express transmission line, which would connect wind farms in Kansas to the eastern US. Last month, Wright said he sees intermittent power sources as a "parasite on the grid". The Energy Department did not respond to a request for comment.

The Energy Department, in a document released this month, indicated it did not plan to spend $383mn that had already been appropriated for wind and solar projects this fiscal year under a bipartisan funding law Trump signed, a unilateral spending reduction that US senator Patty Murray (D-Washington) and US representative Marcy Kaptur (D-Ohio) said was "outrageous" and unlawful.

The Trump administration also temporarily halted construction of the fully permitted Empire Wind project off the coast of New York, before allowing work to continue in May. US interior secretary Doug Burgum last month said in congressional testimony that the administration was reviewing "all offshore wind projects" and said there was "no appetite" for adding more "intermittent, unreliable [power] to the grid."

Threat to dominance

Democrats say attempts to undermine wind and solar will be counterproductive to Trump's own priorities of "energy dominance" because they are among the limited types of projects that can be brought on line quickly. US utility executives and data center developers have said they are facing wait times of three years or more for delivery of turbines for gas-fired turbine, given a surge of global demand for electricity needed for artificial intelligence.

"There's a backlog of gas turbines, and geothermal and nuclear takes many years. Nothing else is ready," US senator Brian Schatz (D-Hawaii) said in a social media post last week. "Republican energy policy is to create shortages because they think solar is liberal."

Clean energy groups are hoping that Republican lawmakers will pay a political price for voting to cut clean energy tax credits through Trump's recently signed tax and energy law. The industry group Clean Energy for America last week said it launched a billboard advertising campaign that it said was targeted against seven House Republicans who voted for the law.

"We're making it clear who is responsible when constituents lose their jobs and find that their monthly electricity bill is higher than they can afford," Clean Energy for America president Andrew Reagan said.

By Chris Knight