Hot Air As An Energy Source

There are a lot of different kinds of renewable sources be researched and built (solar, wind, wave, etc.). Now an Australian entrepreneur wants to build a new kind of energy plant in the Arizona desert -- a hot air tower. Roger Davey, owner of EnviroMission, originally wanted to build the energy-producing tower in his home country, but believes the political climate is better for it in the United States.

His hot air tower makes use of the fact that hot air naturally rises, and the taller the tower the faster the air will rise inside it. He plans to use the rising air to turn multiple turbines which will generate the electricity. His tower, which would be the second tallest man-made structure in the world, would produce about 200 megawatts of electricity (enough for the needs of about 100,000 homes).

This is not a totally new idea. A smaller hot air tower was built in Spain, and produced about 50 kilowatts of electricity a day before being toppled in 1989. China is currently building a much larger one that will produce hundreds of megawatts. Davey wants to build his giant structure of concrete to keep it protected from falling. Here is how the BBC describes the hot towe concept:

The technology works like this: Unlike normal solar photovoltaic panels that convert the sun's light into energy, the EnviroMission tower would create solar-thermal power, from both the sun and the wind.
Like a greenhouse, the sun heats up the air underneath a huge translucent, sloping canopy around the tower that is about as wide as a football field.
The air is heated to about 194 degrees Fahrenheit (90 degrees Celsius) and then it flows into the tower, spins the turbines and rises.
The higher the tower, the stronger the flow of air. The faster the turbines spin, the more electricity possible.
After sundown, the ground continues to release heat and more electricity would be generated.


This type of renewable energy would not solve all our energy problems, or be appropriate in all locations. But it sounds like a good idea for the states where a lot of heat is normal. I hope he can get it built because we need to be trying all of the current ideas out. The coal won't last forever (and is destroying the environment), and it make take a variety of solutions to replace it. Water, geo-thermal, wind, wave-motion, solar, and hot air towers may all be a part of the future energy production for the U.S. and the world (and probably some other things that haven't yet been thought of).

The only thing keeping the Arizona project from being built right now is money. Davey thinks it will take a little more than $700 million to build the tower and make it operational. That may sound like a lot of money, but as power plants go it is not outrageous. A new coal-powered plant to produce 400 megawatts of electricity in North Carolina is projected to cost $1.83 billion to build (and that doesn't count the cost of all the coal they'll have to purchase). The hot air tower will have no fuel costs at all -- since air is free, as is the solar power used to heat it.

It's just another interesting idea. And it's the kind of thing we need to be investing in these days.