Donald Trump recently told Republican congressional leaders that the wall should be covered with solar panels and the electricity generated could be used to pay for the wall, since the Mexicans won’t. According to AXIOS:
Trump said his vision was a wall 40 feet to 50 feet high and covered with solar panels so they'd be "beautiful structures," the people said. The President said that most walls you hear about are 14 feet or 15 feet tall but this would be nothing like those walls. Trump told the lawmakers they could talk about the solar-paneled wall as long as they said it was his idea. One person cautioned that the President wasn't presenting the solar-paneled wall as the definite solution.
Many supporters of the president think it is a great idea that will neutralize opposition to the wall, with comments like “The greenies can't argue with a massive solar farm can they?” and “Gosh I love how green our POTUS is!!! Build that Wall!!!”and “Al Gore supporting the wall in 3... 2... 1…” Republicans in congress seem to like the idea:
“I think it’s innovative,” House Majority Leader Kevin McCarthy of California told the paper. “To authorize it and to appropriate it wouldn’t cost as much.”
“He’s been looking at a lot of options and this is a new option that he’s been looking at that sounds like its got real promise,” House Majority Whip Steve Scalise, R-La., said.
Although the President claims that it was his idea, the pump was primed for this by one of the respondents to Homeland Security’s proposal call a few months ago, from Gleason Partners. They said at the time:
The panels would provide electricity for lighting, sensors and patrol stations along the wall. Sales of electricity to utilities could cover the cost of construction in 20 years or less, according to the company. Power could also be sold to Mexico. “I like the wall to be able to pay for itself,” said managing partner Thomas Gleason.
But back in February, Bryce Elder of the Financial Times did some serious research and concluded that there were lots of problems, including alignment (the border is not a straight, east-west line) angle (vertical panels get less energy) susceptibility to graffiti on the Mexican side where the panels are.
However a commenter to the FT provided calculations that show it to be a sensible idea that will pay for itself in 8.43 years.
Build it out of coal!
Another idea that would make the wall even better would be to build it out of coal. One could use big rocks and build a rubble wall or one could mix it with cement and make bricks out of it. Or one could use the coal as aggregate in concrete. This would go a long way toward dealing with the hurt feelings of those in the coal industry who hate solar power.
The best coal for the job is anthracite, because it is the hardest, almost pure carbon, the most rock-like. Most of it is in northeastern Pennsylvania, which has 20 billion short tons of the stuff.
Conventional concrete is 75% aggregate. If coal was substituted for gravel in a wall that is 40 feet high (as Trump wants it) and three feet thick, running the length of the border, this would consume close to 40 million short tons of coal. but that’s not really very much; the whole country produces 900 million short tons every year.
The answer here is to make the wall thicker, sort of like the Great Wall of China. This could help turn it into a major tourist attraction, helping defray even more of the cost. We know that engineers like 20 feet for emergency vehicles, that would be close to 269 million short tons of coal, almost a third of the entire production in the US. This could revolutionize the anthracite coal world; Pennsylvania only mined 1.8 million tons of it last year, and all of America, 5 million tons. This would really put the pits back into Pittsburgh.
This might be the perfect answer to make everyone happy: a wall built of coal, sequestering the carbon for the life of the wall, covered in solar panels generating clean energy. It is such a win-win that we will be tired of winning.