[Tanada]

I have been searching for over a year now on and off, unsuccessfully, for details on a green energy system I read about many years ago. If anyone has links to information on this system or a book about it they could share the title of I would be very appreciative!

The system works like this, build a structure that looks like a tall grain elevator. Put a set of vents around the very top of the structure. One meter below the top of the structure mount a wind turbine generator horizontally, with a rotor diameter slightly smaller than the inner diameter of the structure. One meter below the wind turbine mount a ring of water mist projectors. At the bottom of the tower have another set of vents distributed around the base of the structure.

The system operates by pumping cold water through the mist projectors just under the turbine. The cold mist absorbs energy from the ambient air and falls because both it and the cooled air are denser than ambient. As the colum falls air is drawn into the top of the tower through the upper vents, passes the turbine causing it to spin. After spinning the turbine the air is cooled with the water mist and continues to fall drawing more air into the top vents. At the bottom of the structure the cool dense moist air escapes via the vents at the base of the structure, which are about 20% larger than the intake vents at the top.

So long as electricity is supplied to the water pump and ample water is availible to send through the mist projectors the tower will draw air through the turbine and produce power. These systems are only practical in areas with ample water to use but one suggestion was to co-locate them with waste water treatment facillities. Treated waste water is cleaned to environmentally 'fresh' standards and then dumped back into the environment, it is already clear and low contamination by design and has no further economic value to the treatment facility. By running a portion of the waste water through one of these 'water chimney' power systems a waste water plant is suppossed to be able to generate all the energy it consumes to process sewage, without any addition to environmental damage.

You could also place these 'water chimney' systems around the Great Lakes or any other fresh water lake or river so long as the water is filtered before you use it in the misting system.

The numbers IIRC were that one of these self consumes 20% of the power it generates to pump the water, the other 80% is availible for baseload grid application.

[Ludi]

This one?

http://www.macdialup.com/zwilliams/arubot.htm

[Aaron]

Since the energy required to lift the water to the top of the tower is the critical factor, you should be able to determine the actual percentage efficiency yourself using the following information.

Of course you will have to estimate what you think the average power output of the turbine would be.

Water horsepower (WHP) is the power required to lift a given quantity of
water against a given total dynamic head.

WHP = (Q ´ H) ¸ 3960, where Q = flow rate in GPM and H = total
dynamic head in feet.

Brake horsepower (BHP) is the required power input to the pump.
BHP = WHP/E, where E = pump efficiency

Power unit horsepower

Electric power units: approximate name plate horsepower = BHP ¸ 0.9
Internal combustion units:

Must derate 20 percent for continuous duty (= 80 percent efficiency)
5 percent for right-angle drive (= 95 percent efficiency)
3 percent for each 1,000 feet above sea level (= 91 percent for
3,000 feet)

1 percent for each 10° above 60°F (= 96 percent for 100°F)

Approximate engine horsepower required = BHP ¸ deratings
= BHP ¸ (0.80 ´ 0.95 ´ 0.91 ´ 0.96)

[Tanada]

This one?

http://www.macdialup.com/zwilliams/arubot.htm

{thudding noise from banging head on desk}

Thanks Ludi, once again it is proven that Google hates me. The site you found is a derivative of the orriginal idea I came across some some 25 years or so ago, and from what they say there still has not been so much as a ground breaking ceremony.

They also say it only works in arid climates, which is not something I had seen before, and that you need a 1 km high or higher tower for it to produce competitive priced power.

Yet another green power supply killed by reallity, I can't imagine everyone rushing out to build these with their massive cost investments and low return on investment ratio.

[Tanada]

The link above is dead but Google still has is Cached
http://en.wikipedia.org/wiki/Talk%3AEne ... t%29/Zwirn

http://en.wikipedia.org/wiki/Energy_tow ... wndraft%29

[lper100km]

It’s just another extremely inefficient way to generate power. There might even be an energy output, but so small that it is virtually useless. Every change of state induces energy losses. If you have enough available energy to pump water up the tower, it would be best to use that to power directly whatever you wanted to power after you had generated the power from the tower.

If water is available from a point higher than the tower, it would be much more efficient to use that in a water turbine than to go through the rigmarole of evaporative cooling.

It’s far worse than generating hydrogen using fossil fuels or fossil feedstocks or any other hair brained process for manufacturing fuel.

This is not quite in the perpetual motion category and is on the margin of energy multiplier scams. But it is on the far side of being ridiculous, which is probably why nothing has happened and the links are dead.

[Tanada]

I found a working animation on Youtube and they claim to be ready to build the prototype in Israel, of all places, using filtered sea water. They are claiming it will take 33% of the energy produced to run the pumps and 20% will be lost to the grid before it can be used for productive efforts leaving a net 47% gain in energy.

Not exactly an overwhelming level of output, but if it works hey more power to them. Somewhere or other they state best use would be coastal desert industrial use to eliminate line losses by adding it to the grid. If you have a few Billion lying around unused maybe you can build one on the coast of Mexico and use it to power an aluminum smelter refining Jamaican bauxite. They claim it will generate for 3 cents per kWh in the prototype 1200 meter tall version.

Heck if it actually works they could put one next to the Burj tower in the Persian Gulf and use it to power the tower.

[Keith_McClary]

It depends on evaporation to cool the air, so it wouldn't work in a humid place. Also, I think it wouldn't work very well in a cold dry place since evaporation would be slower (haven't done the math). So you need a hot, dry place with water available.

In a hot sunny location you could use a similar tower and turbines to make a solar updraft tower as prajeshbhat has discussed:
Will this work?

Whether up or down is more effective depends on temperature, humidity, sunlight and availability of water. Maybe you could build one that switched from one mode to the other depending on conditions.

[Tanada]

I was kind of picturing building an Arcology shaped like this proposed Israeli tower, the wall would be about 10 meters thick and would be units stacked atop one another like any other skyscraper. The difference is you would be living inside your own power generating station, you could put apartments, maintenance, business offices, manufacturing facilities all in the wall as your build upwards with communications and luxury penthouse high up. Think the Burj tower scaled up with about 50 times more space and huge quantities of electricity on demand cheap.

We had an Arcology discussion once
arcology-anyone-t54671.html?hilit=arcology
Not the way I want to live, but for people who want to live in cities they sure are the best in terms of land use.

[Subjectivist]

I have been searching for over a year now on and off, unsuccessfully, for details on a green energy system I read about many years ago. If anyone has links to information on this system or a book about it they could share the title of I would be very appreciative!

The system works like this, build a structure that looks like a tall grain elevator. Put a set of vents around the very top of the structure. One meter below the top of the structure mount a wind turbine generator horizontally, with a rotor diameter slightly smaller than the inner diameter of the structure. One meter below the wind turbine mount a ring of water mist projectors. At the bottom of the tower have another set of vents distributed around the base of the structure.

The system operates by pumping cold water through the mist projectors just under the turbine. The cold mist absorbs energy from the ambient air and falls because both it and the cooled air are denser than ambient. As the colum falls air is drawn into the top of the tower through the upper vents, passes the turbine causing it to spin. After spinning the turbine the air is cooled with the water mist and continues to fall drawing more air into the top vents. At the bottom of the structure the cool dense moist air escapes via the vents at the base of the structure, which are about 20% larger than the intake vents at the top.

So long as electricity is supplied to the water pump and ample water is availible to send through the mist projectors the tower will draw air through the turbine and produce power. These systems are only practical in areas with ample water to use but one suggestion was to co-locate them with waste water treatment facillities. Treated waste water is cleaned to environmentally 'fresh' standards and then dumped back into the environment, it is already clear and low contamination by design and has no further economic value to the treatment facility. By running a portion of the waste water through one of these 'water chimney' power systems a waste water plant is suppossed to be able to generate all the energy it consumes to process sewage, without any addition to environmental damage.

You could also place these 'water chimney' systems around the Great Lakes or any other fresh water lake or river so long as the water is filtered before you use it in the misting system.

The numbers IIRC were that one of these self consumes 20% of the power it generates to pump the water, the other 80% is availible for baseload grid application.

This actually seems like it would actually work, if anyone would actuall build one to test it out that would be great.

[ROCKMAN]

Sub - "So long as electricity is supplied to the water pump and ample water is availible to send through the mist projectors the tower will draw air through the turbine and produce power." So the plan is to use electricity to produce electricity. And the system will generate more electricity then the system uses to create the electricity. So until the moving parts wear out you have essentially created the elusive perpetual motion machine. Sounds good to me...where can I buy stock in this company that will certainly be a big success.

[sparky]

.
the thermal convexion systems have all the same problem ,
...lousy torque ,
when one increase the diameter of the fan , the weigh become a major issue .

it's like creating a very gentle breeze to power a windmill
a somewhat less feeble system is thermal convection in water , density does matter
immersion can also make the system buoyancy neutral
it still probably wouldn't work but could be power positive

[Zarquon]

Hey, it's only a 1200m tall tower. I've heard they'll make it out of recycled cardboard.

[AdamB]

Hey, it's only a 1200m tall tower. I've heard they'll make it out of recycled cardboard.

Here is a slightly different version of what appears to be the basic idea. 200,000 homes powered by this thing, maybe. Probably never finished, between other types of renewable construction expanding rapidly during the transition and even more hugely expanding natural gas supplies, but still a good idea.



http://www.solaripedia.com/13/371/5042/ ... plant.html

[vtsnowedin]

The tallest building in the world is 829 meters high so I doubt you can build anything 1200 meters high and certainly not for cheap.

[Tanada]

I find it amusing that several people say 'the math proves it won't work' without anyone having ever built a working model to real world test. After all 'math' said the same thing about balloons, and then again about heavier than air flight, and about trains going more than 10 mph and about cars going more than 25 mph and on and on. Math only works if you have all the variables right, and that is rare in a model until a real world model gets tested to show what you missed.

[MD]

Low EROEI. These are the kinds fo projects that my deeply liberal friends keep proposing as our salvation to the future. These are the same people that want to stop all phosphate and fossil fuel production, while opening the borders to the unfortunate masses of the world, while asserting that organic gardening and electric cars will fill the gap.

The same people that hate industry and technology in one breath while insisting in the next that innovation will solve the problems.

I've stopped talking. When I tell them that 5 billion people have to die in order to realize their utopian vision, they stop listening.

lol.

I give up!

[AdamB]

The tallest building in the world is 829 meters high so I doubt you can build anything 1200 meters high and certainly not for cheap.

Cheap isn't a requirement. Just look at California electricity prices compared to many other places. They manage to do pretty good as an economy without having cheap electricity in the equation.