EnviroMission is in the “Final – Feasibility” phase of its 200-megawatt solar updraft tower and according to a company press release has contracted Hensel Phelps to deliver the site specific project in La Paz, Arizona. It will take two years to build and the estimated completion is in 2015
The “Solar Chimney”, as it sometimes called, will sport 32 massive turbines powered by heat draft that comes from a 2 mile greenhouse canopy surrounding the base of the tower. It will produce enough electricity to power between 150-200 thousand homes.
This is an expensive and audacious project. It will be 2600 feet tall which is more than twice the height of the empire state building and is slightly higher than the world’s tallest building Burj Khalifa. This project has been calculated to pay off in 11 years and perhaps sooner because it is totally passive at 60% efficiency and requires no water. This makes it a contender for commercial viability to support the grid with other alternatives and traditional utilities.
The Solar Tower is not without its critics. Frequent among questions is “Why does it have to be so high”? The driving force in Solar Chimneys is the weight difference between the hot light air inside the chimney flue and the corresponding heavy cold outside air. Another good question is that “Doesn’t solar panel farms produce more energy for more efficiently”? That one is tougher to answer. Both are expensive at this scale. Over time the cost can come down to about 18 cents a kilowatt-hour. That is still high compared to coal-fired power plants that cost only 6 cents per kilowatt-hour.
However, we are trying to move towards clean renewable energy. The one factor that sticks out in my mind is the monthly or annual maintenance costs. Heliostat or Photovoltaic panels need to be cleaned for peak efficiency. Perhaps a large concrete solar chimney doesn’t need much maintenance. I guess it is possible. It will take $750 million to erect this solar tower and it should last maintenance free for 80 years.
So if this concept is so old has it ever been tried? Yes, in Manzanares Spain with German designer Schlaich Bergermann. It was a small scale plant with an output of 50 Kilowatts. It ran from 1982 to 1989. It was a “proof of concept” project that was run for three years to get the data needed to determine larger scale projects.
This concept is quite old. One of the earliest descriptions of a solar chimney power plant was written in 1931 by a German author, Hanns Günther. In 1975, Robert E. Lucier applied for patents on a solar chimney electric power generator; between 1978 and 1981. Lucier’s patents have expired, however have been renewed by companies in Australia, Canada, Isreal and the US.
It will be interesting to see when it gets built.
Sources
- www.enviromission.com.au
- www.solar-tower.org.uk
- www.digitaltrends.com
- www.gizmag.com
- www.evwind.es
- www.greentechmedia.com
