Tech + Engineering

02
May

Proposed Hyperboloid Energy Tower Uses Simple Math to Solve a Big Problem

In a small town near the U.S.-Mexico border, a lofty dream could become a towering reality.

The company Solar Wind Energy, Inc. is only three years old but it’s already proposed building a 2,250-foot tower, situated in the desert near the Arizona-Mexico divide, that could deliver 500 megawatts of power to the electrical grid. That’s nearly as tall as the 2,722-foot Burj Khalifa in Dubai.

cooling-tower
Cooling towers are also built as hyperboloid structures.

San Luis, a town of less than 28,000 people, was chosen as the site of this “energy skyscraper” because it’s sweltering, arid, and its climate is closely monitored for the several military operations close by. The tower would take water from the Sea of Cortez, some 46 miles away, and pump it to the top of the massive concrete structure, where it would be released in a mist. This cools the air, making it denser and causing it to sink.

Here’s David Ferris, writing for Forbes.com:

That heavy air sinks and accelerates, reaching speeds of 50 miles an hour before escaping at the base via 52 tunnels, where the rushing air spins turbines and create electricity.

Each tower would generate 610 megawatts of electricity, of which about 100 would power the plant. The remainder would go to the power grid.

The energy tower works efficiently due to its hyperboloid shape. Water enters at the top, where the volume is larger. There the air cools and begins its descent. As it passes through the narrower middle, it accelerates thanks to Bernoulli’s principle before exiting through the turbines. The greater the temperature difference, the more power that can be created. The company is predicting that they can cool the dry, desert air by as much as 40˚ F.

One limiting factor here is the amount of water, which in the southern Arizona could be an issue. Ferris reports that the tower would reportedly be able to recycle up to 75 or 80% of the water it uses.

At least $1 billion, the project will be costly. Plus, only a scale model has been built, and it’s only four feet tall, though the company claims that its design can grow the additional 2,244 feet without substantial changes to the design.

The project has received the green light from federal agencies, though city approval is still in the works and there’s still an environmental impact report that needs to be completed. Plenty of hurdles remain, but if the tower works at sufficiently high efficiency, it could be a predictable source of renewable energy.