A new idea has emerged for how the United States can foot the bill on President Donald Trump’s proposed U.S.-Mexico border wall: cover it in solar panels so the wall will pay for itself.

The president proposed this idea in a meeting yesterday (June 6) with Republican congressional leaders, reports news site Axios. According to the publication, three people “with direct knowledge of the meeting” said that Trump mentioned this idea, elaborating that the solar panel-covered wall would be 40 to 50 feet high and look like “beautiful structures.”

His comments are a bit ironic given that he pulled out of the iconic Paris Agreement last week, on June 1, which would have encouraged further solar development in the struggle against climate change. His comments are also a stark contrast to previous comments the president has made on solar energy, including that it’s “expensive” even as its costs continue to drop.

This isn’t the first time the idea has been expressed. The Associated Press reported in April that veteran-owned construction business Gleason Partners LLC submitted a border wall design idea to the administration that included solar panels, which would provide electricity for lighting, sensors and patrol stations along the wall. Per the AP’s reporting, these sales would cover construction costs in 20 years or less.

Many environmentalists aren’t into this idea, though—even if it means a smaller carbon footprint. In fact, some are not into the idea of a border wall whatsoever, as made evident in the first-ever lawsuit filed against the Trump administration over the wall. The lawsuit sheds light on the environmental impacts the wall would have, including dividing ecosystems—as well as communities.

In a statement The Hill energy and environment reporter Timothy Cama posted to Twitter, Brett Hartl, government affairs director for the Center for Biological Diversity, one of the plaintiffs, said this:

And as Joe Romm, the founding editor of Climate Progress, an environmental-focused news site, wrote today (June 7): “[S]kip the wall and just put solar panels directly on homes.”

Still, this doesn’t mean that all environmentalists would not possibly support the idea, even if it means building the wall. The Atlantic published a story today showing the linkages between “pro-nature sentiment” and “anti-immigration politics.” As The Atlantic elaborates:

Some contemporary figures in immigration restrictionism began in the environmental movement. John Tanton, who founded three immigration-lobbying groups, including the Federation for American Immigration Reform, began his involvement in politics through environmental activism. He says he once lobbied the Sierra Club to adopt anti-immigration positions; when they demurred, he founded his own network of groups.

Today, the Southern Poverty Law Center calls Tanton “the racist architect of the modern anti-immigrant movement.” They cite a letter of Tanton’s held at the University of Michigan, in which he writes: “I’ve come to the point of view that for European-American society and culture to persist requires a European-American majority, and a clear one at that.” (The New York Times covered the relationship between Tanton and the SPLC in April.) Linda Chavez, a veteran of the Reagan administration, has said that Tanton is both “anti-Hispanic” and “anti-Catholic.”

Tanton’s own website describes him as a supporter of “population stabilization” and “environmentally sustainable immigration numbers.”

The latest attempt to marry the environmental movement with the anti-immigration one will be difficult though, as Romm lays out in his story. The U.S. side of the border isn’t ideal for solar panels given how far removed it is from population centers. This means that it would require a multibillion-dollar power line. And then there’s potential flooding, which the South is seeing more of—thanks to climate change.