It looks sinister, like the stack of a nuclear or coal-fired power station, but its promoters say it will generate totally clean electricity 24/7 using entirely natural processes.
How? Well, the wind turbines at the bottom provide a clue.
The tower is very tall, 685m, twice the height of the Eiffel Tower, and made of concrete.
Water is pumped up to the top and sprayed as a mist over the opening. Evaporation cools the air, so it drops, fast, at around 50mph. When it hits the bottom it spins the turbines.
And that’s about it.
The basic idea was patented back in 1975 by a Phillip R. Carlson and has since been expanded by others.
But now a US company plans actually to build one of these "downdraft towers" and hopes to license the technology all over the world.
In April, Maryland-headquartered Solar Wind Energy got approval to build the first one near San Luis, Arizona. Arizona works because it’s hot and dry.
The company, which holds a number of patents on the technology, with more pending, says the tower will generate around 435MW – nearly the output of a very little nuclear power station – without emitting any greenhouse gases.
The company says it is looking at other sites around the world, in north Africa, India and the Middle East. Its business model would see project partners license the technology "off the shelf", while it makes money through licensing fees and royalties collected on the power produced.
Without a doubt, it’s an elegant idea. US investor JDF Capital Inc. certainly thinks so: two weeks ago, on 16 June, it decided to finance Solar Wind Energy to the tune of $1.6m.Â
Whether these very high towers sprout up all over the US may depend, however, on project partners coming up with more elegant designs.