[PrestonSturges]

I've thought about the home solar chimney in terms pulling geothermally cooled air upwards in the summer. I see no prospect of it working for anything except passive air circulation.

[prajeshbhat]

Hmmm..Still..If it could produce wind srong enough to light a bulb or two, it could be useful for some applications. Right now i am not looking for any "saving the world" miracles.

[radon]

Linked is wind generator that looks suitable for use in the design you proposed:

http://www.jetprotech.com.tw/en/products/jps200.htm

It generates "rated power" of 200W, its voltage is 48V at highest. Its diameter is ~0.1m meaning radius of the chimney of 0.05m for the generator to fit perfectly, half as much as in the example, giving you ~4 as much time for air replacement and heating in the example in the thread above. But its "rated" wind speed is 12, 4 times as much as in the example, giving you less time for air replacement also by a factor of 4 (coincidentally). I.e. the design should theoretically work with this generator as long as it is able to heat the air to the desirable temperature within a minute, as much as in the example. But air flow of 12 m per second, fairly strong wind, would hardly be achievable anyway in your design, the temperature differential appears to be too low.

Maybe there could be some design solutions improving the situation, like using smaller size chimney with this generator.

[prajeshbhat]

Thanks for the link. The small wind turbines look good

[Subjectivist]

How much room do you have? It sounds like several of the small turbines would give you more energy to work with than this solar chimney field.

[prajeshbhat]

$this->bbcode_second_pass_quote('Subjectivist', 'I')t sounds like several of the small turbines would give you more energy to work with than this solar chimney field.

[SeaGypsy]

Way better idea:

http://www.youtube.com/watch?v=fUrB7KRvxUk

Fresnell solar Sterling engine (ramp this up a few notches....)

[prajeshbhat]

Concentrated solar power is fine..But it comes with several complications. Suntracking, keeping the concentrator clean, maintenance etc. I want the simplest possible device.

[SeaGypsy]

How much is child labor worth where you are in India?

[prajeshbhat]

Child labour is cheap (though if you get caught it will cost you dearly).
But using children for moving the concentrator periodically will not work for long. The problem is with the concentrators themselves. All types of concentrators wear and tear due to exposure to the elements. They don't last very long.

[Subjectivist]

Do you get a lot of rain? Have you heard of the reverse of the Solar tower, the water mist tower? In the mist design you are a little more complicated than the solar tower but it takes much less space and you need a steady supply of filtered water, it doesn't have to be potable just filtered. You put a turbine at the top of the chimney and then right below the turbine you put a spray system to put out a very fine mist of water. The water increases the density of the air in the chimney and forces it to sink to the bottom where you have an exit screen for the wet air to escape through. You need less power to pump the small volume of water at high pressure than you get out of the turbine at the top so the system is net generator of electricity.

Is there some way to search the web site? Somebody might have already talked about them on here.

[Tanada]

water-energy-tower-concept-t17111.html

I use search.php to search, it works well for me. Others prefer the google search at the top right of each page.

[prajeshbhat]

$this->bbcode_second_pass_quote('Subjectivist', 'D')o you get a lot of rain? Have you heard of the reverse of the Solar tower, the water mist tower? In the mist design you are a little more complicated than the solar tower but it takes much less space and you need a steady supply of filtered water, ......

[Keith_McClary]

Atmospheric Vortex Engine
http://phys.org/news/2012-12-entreprene ... power.html
http://vortexengine.ca/english.shtml

$this->bbcode_second_pass_quote('', 'T')he Atmospheric Vortex Engine has the same thermodynamic basis as the solar chimney. The physical tube of the solar chimney is replaced by centrifugal force in the vortex and the atmospheric boundary layer acts as the solar collector. The AVE needs neither the collector nor the high chimney. The efficiency of the solar chimney is proportional to its height which is limited by practical considerations, but a vortex can extend much higher than a physical chimney. The cylindrical wall could have a diameter of 200 m and a height of 100 m; the vortex could be 50 m in diameter at its base and extend up to the tropopause. Each AVE could generate 50 to 500 MW of electrical power.

[pinglepongle]

Flatulence-vortex-freeenergy
Time to give Khosla a call....

Cleantech Still Holds an Allure for Khosla Ventures
Posted on: November 05, 2012

For a firm with a substantial portion of its portfolio in clean technology, Khosla Ventures seems to be doing pretty well. The firm’s Fund III had a portfolio worth 1.3 times invested capital as of the end of March, according to the California Public Employees Retirement System (CalPERS). A seed fund raised in 2009, meanwhile, had a multiple of 1.1.

Overall, the numbers look better than one might expect, given that the firm is famous in Silicon Valley for its embrace of alternative fuels and other cleantech sectors which have performed badly in the last couple years. Though that’s not the firm’s only area of focus (it’s also quite active in the mobile, Internet and consumer health spaces, among others), cleantech has historically accounted for close to half of investment dollars, according to Thomson Reuters data.

So far this year, the vast majority of rounds backed by Khosla Ventures have been outside the energy industry. However, that does not mean the firm is moving away from sustainability-minded investments, founder Vinod Khosla says.

Rather, with fewer co-investors remaining in the space, the firm expects to back fewer individual companies and to allocate more capital to each one. The plan is to also continue making early stage investments with technical risk.

“When you invest early in cleantech, so many people are afraid to take a risk that you get extremely attractive valuations,” says Khosla, who notes that the firm was a seed or very early-stage investor in many of its portfolio companies in biofuels and other cleantech sectors, which enabled it to take a significant stake at a low valuation. Though valuations may be down from their pre- or post-IPO peaks, they’re still much higher than they were at seed stage.
Yawn.

[prajeshbhat]

I have received suggestions that using a metal sheet canopy would be inefficient since it will not assist the direction of air flow since the air is scattered all over the canopy area. Instead i could use black painted pipes/tubes with one end of the pipes opening into the bottom of the chimney. The draft created by the chimney will pull the hot air in the pipes towards it. The tubular shape of the pipes will make the air flow more directional.
Is that a good idea?

[Graeme]

Solar Wind Energy Tower, Inc. Innovative Design And Construction Methods Reduces Capital Costs And Improves Financial Performance Of Downdraft Tower

$this->bbcode_second_pass_quote('', 'S')olar Wind Energy Tower, Inc. (OTCQB: SWET), (the “Company”) announced today that the Company has successfully managed to economize the Tower by reducing expected capital costs and improving projected financial performance. Some of the best consultants in the world have been working diligently towards bringing the first Downdraft Tower to market.

The Company recently announced the completion of weather data models that confirm the first tower height was lowered from 3,000 feet down to 2,250 feet. Reducing the Downdraft Tower’s height and shape enables the structure to be built much more affordably using the newest formulations of industrial concrete. The benefits of concrete translate into dramatic savings in a number of areas. Concrete is less expensive that steel and is readily available around the world. The newest concrete construction methods enable the concrete to be mixed at ground level and pumped to every level under construction and poured in place. This construction method is much faster than building pre-cast sections on the ground and transporting each section to the required level. The time to construct each tower is dramatically reduced along with the cost of construction.

This development was made possible by utilizing our recently announced software which can calculate and predict energy production by our Solar Wind Downdraft Towers given local weather data. By feeding the weather data for southwestern Arizona/ Northern Mexico into the program, the Tower’s height and diameter was adjusted along with the amount of water added as fuel to create a desired amount of energy. The outcome dictated the optimum size of the Towers height and width. Solar Wind Energy can now evaluate potential Tower sites around the world and calculate and predict the shape and size of the Tower and the amount of electricity that can be produced in any region. Multiple Towers can be deployed in “Compounds” using the same cranes, water source, delivery, manufacturing and construction systems and labor forces.

Under the most recent design specifications, the first San Luis Tower is expected produce abundant, inexpensive electricity with a design capacity on an hourly basis, of up to 1,250 megawatt hours, gross. Using a 60% capacity factor, we expect the Tower’s potential hourly yield equates to 600 megawatt hours, from which approximately 18.5% will be used to power its operations, yielding approximately 500 megawatt hours available for sale to the power grid. Factoring in lower capacities during winter days, the average daily output for sale to the grid for the entire year is approximately 435 megawatt hours per day. Currently in California avoided costs are running approximately $0.11 per kilowatt hour. As an independent power producer of clean renewable energy, the Company will be selling power directly to the power grid rather than directly to consumers.

[Tanada]

I have been doing my usual year end round up searches and came across a link posted two days ago that leads to this article about a test tower built in Wuhai, China.

$this->bbcode_second_pass_quote('', 'A') test plant is running successfully in Inner Mongolia and scientists want to build full-size versions in cities such as Beijing and Shanghai. The researchers have suggested the towers could be constructed inside new skyscrapers.

The technology involves covering an area of several square kilometres to create a greenhouse around a high chimney. The hot air produced in the greenhouse rises through the tower, driving turbines that generate electricity. The higher the tower, the stronger the updraft and the more power created.

The highest previous attempt to master the technology, which has been discussed for decades, ended in failure when a 195-metre tall tower in Manzanares, Spain, collapsed in 1989 due to structural failure.

But Professor Wei Yili , the leader of the project at Inner Mongolia University of Science and Technology, said he was confident they could now build safe and efficient towers higher than a kilometre.

"The structural problem is no longer a problem for us. We have acquired patents for our technology and design," he said. "The towers will stand for a century, outlasting those who build them or see them built, like the Eiffel Tower."

The 50-metre high test "solar updraft tower" has been running in the Gobi desert in Wuhai for nearly four years.

Scientists wanted to build a chimney as high as 200 metres, but had to rein in their ambitions because of a nearby airport.

"This is the biggest regret of the project," Wei said. "Our power generation capacity and efficiency have been severely restricted by the limited height."

The project has managed to generate up to 4,800 kilowatt hours of electricity a day.

[Newfie]

I wonder what the equivalent solar production would have been, say had an equivalent size patch of dart been covered with PB panels.

I often wonder why we don’t build more of of covered car parks, especially in places like Florida. Seems an obvious use of the space which also provides shade for the cars and people with no land acquisition cost.

[Tanada]

$this->bbcode_second_pass_quote('Newfie', 'I') wonder what the equivalent solar production would have been, say had an equivalent size patch of dart been covered with PB panels.

I often wonder why we don’t build more of of covered car parks, especially in places like Florida. Seems an obvious use of the space which also provides shade for the cars and people with no land acquisition cost.