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Interview: EnviroMission Solar Tower
Through the patented solar storage capacity of salts, with selective
release of the heat to run the turbines at the base of the tower, this may well
be among the first renewable energy source to achieve "primary
provider" status, meeting the demand profile, at grid-competitive pricing.
Interview
Recording (54:37 mins; 22 MB; MP3)
Shortcut: http://tinyurl.com/tesm3
EnviroMission video
provides a ~3.5-minute animated tour of the solar tower and its function.
(7.6 MB). An earlier design anticipated a 1000 meter height -- 2x
the height of the Empire State Building. |
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MELBOURNE, VICTORIA, AUSTRALIA -- On Oct. 28, Sterling Allan hosted a live
interview with Roger Davey, CEO of EnviroMission of Australia, which is a
leading developer of the Solar Tower technology.
The tower is surrounded by a solar skirt which gathers the solar heat energy
into the central column, creating an updraft, which can turn turbines for
generating electricity.
 EnviroMission
had a smaller prototype built in Spain in the 1980s, which was 200 Meters high,
with a skirt that covered 8 acres. They were able to gather a great deal
of data during the seven years that it was in operation.
One thing those tests showed is that even on cloudy days, there is enough solar
penetration to run the system, with only a slight drop in power. The
primary driver is the heat differential, which is still maintained on cloudy
days.
A publicly traded company (NY pink sheet EVOMY),
they are presently in process of finishing computer modeling by which they will
be able to determine the best size to build commercially. The objective is
to optimize the size-output ratios.
They have determined that it is not necessary to go as high as 1000 meters (as
shown in their video)
in order to generates adequate updrafts. The economics of the 1000-meter
design were sound, but the improved efficiencies will be even more so.
They have refined their heat retaining and heat-absorbing technologies to a
point that will enable them to actually run the plant 24-7, meeting the peak
demand grid usage needs in the morning and evening, by selectively releasing the
stored heat -- a proprietary process that involves salt ponds. They will
employ a durable transparent panel developed by an Australian university that
increases solar heat collection by 10%. Combined, these methods will
enable the plant to run at an average of 80% of its installed capacity,
generating 350 gigawatt-hours per year.
Though the video featured on the site shows a 200 MW plant, they are presently
targeting in the region of 50 MW installed capacity for their first commercial
installation, slated for completion by the end of 2009, with a two-year
construction time. While the first commercial installation will require
subsidies to be competitive with conventional energy, the company's objective
and expectation, based on the data they have collected, is that in the long-term
they will be able to be competitive with grid power without subsidies.
The 1000 meter design began with a skirt height of 1 meter on the periphery, and
rose gradually to 20 meters in the middle where it meets the tower. While
the 200-meter prototype supported native greenery, the larger size and
temperatures expected in the commercial sizes would not likely support plant
life. Davey suggests that it could be used for the drying of fruits and
vegetables -- a sort of massive dehydrator.
The technology is not designed to withstand earthquakes, and will therefore need
to be situated in regions where earthquakes are not a serious concern.
Another geographical consideration is the extent of general solar availability,
as prevails in arid regions. Finally, proximity to existing grid
transmission lines is an important factor in choosing a site.
Approximately a third of the construction cost is in the tower, with another
third in the skirt infrastructure, and the final third in the turbines.
The 1000 meter version was designed to have 32 jet-engine-like turbines oriented
horizontally, each producing around 6.2 MW. Arranged in banks of four,
servicing could be done on one set while the others continued to run.
A location is secured in Australia for the first commercial installation.
In the US, locations in Arizona, Nevada, Texas, New Mexico, and East California
are being considered. China, India, and Pakistan are also engaged in
considering sites for tower installation.
They have determined that it would not be cost-effective nor energy efficient to
build the tower in phases, but will build each tower complete before
commissioning.
EnviroMission is the only company worldwide that is pursuing this solar tower
approach. They hold several patents on the technologies involved.
Other portions of the intellectual property held closely under proprietary
protection.
All factors combined, Davey states that, the solar tower presents "a new
category of renewable energy: a technology that is able to meet the demand
profile." The solar tower power plant can serve as a primary energy
supplier, capable of meeting peak load demands during the morning and evening,
and at a price comparable to conventional energy generation.
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See also
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Page composed by Sterling
D. Allan Oct. 28, 2006
Last updated October 29, 2006
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