Solar energy

Solar Updraft Towers, an alternate, alternative energy source

solar-towerA solar updraft tower collects warm air that forms near the ground, funneled by a canopy, and sends it up a chimney. Turbines in the airflow produce electricity.

I was first made aware of this device from the blog of Dr. Roy Spencer, Principal Research Scientist at the University of Alabama in Huntsville and former Senior Scientist for Climate Studies at NASA’s Marshall Space Flight Center.

Spencer says, “It’s a little like wind tower technology, but rather than just extracting energy from whatever horizontally-flowing wind happens to be passing by, the Solar Tower concentrates all of that warm air heated by the ground into the central tower, or chimney, where the air naturally rises. Even on a day with no wind, the solar tower will be generating electricity while conventional wind towers are sitting there motionless.” And it works at night.

“The total amount of energy that can be generated by a Solar Tower depends upon two main factors: (1) how much land area is covered by the clear canopy, and (2) the total height of the tower.” It also depends on the temperature difference between the power plant’s surroundings and the air underneath the canopy.

A prototype was built in Spain a few years ago.

See here for a You Tube demonstration of this project.

A private company, EnviroMission, is constructing a 200 Megawatt solar tower in the Australian outback.

This technology may be economically competitive with coal fired power plants, unlike current wind or solar generation schemes.

In the Spanish test, they expected that the ground under the canopy would be barren due to the very high temperatures. However, they found that the greenhouse effect (a physical barrier to cooling, unlike greenhouse gases) caused condensation at night and produced lush vegetation under the canopy. Perhaps special crops could be grown at these stations.