1-Kilometer Tower Of Power

!splut writes: "New Scientist has a story about a plan for an interesting new alternative power design. Australian company EnviroMission has recieved approval to construct a 130-meter wide, 1-kilometer tall tower that will generate electricity from currents of air heated within a 7-kilometer greenhouse surrounding the tower's base. It is predicted to generate 670-gigawatt hours of energy per year, providing a clean source of energy for some 200,000 homes."

Comments

watt-hours per year???

[crow]

What a strange measure.

While I realize that the output won't be constant, an average output would be more interesting to most people (at least to me). With 8766 hours per year, the plant is producing on average about 76 megawatts. I seem to recall that the average house draws 2 kilowatts, so that's only 38,000 homes, not 200,000 homes. So their numbers are wrong, my information is wrong, or Australian homes use only one fifth the power of an average American home.

Or is my math wrong?

These don't go *in* cities.

[bill_mcgonigle]

A one mile tall tower could create some castostophic effects should it fall. Beyond just terrorism, accidents still happen.

Worst case scenario, it doesn't crumble under its own weight and falls straight over, with the top landing 1 km from the base. OK, so don't build around it for 1km. 3.14km**2 of land. So, plant corn around it. They don't build any power plants in cities - real estate is too expensive - they send the power over high-voltage AC from a distance.

These would be an air traffic hazard. What a stupid idea.

Good point. We'll get started right away taking down those pesky mountains too.

Concentration: the root of the problem.

[AlecC]

This project seems to me to be attaching what is the root of the problem with all renewables: concentration. When you come down to it, all renewable energy sources are solar power, though many are at second hand. Solar energy drives the weather for hydro, wind and wave, and grows the plants for biomass.

The problem with solar power is that, while there is masses of it, is is relatively diffuse, drops a lot on cloudy days, and comes and goes on a 24 hour cycle. All effective renewable power supplies depend upon some form of a concentrator to make them economically viable - at least for bulk domestic power, rather than specialised uses which can afford the premium cost of solar cells. They also need a load balancer for the 24 hour cycle.

Hydro achieves this by using the landscape - focussing the rainfall into a vally, a lake and a dam. Wind power uses an area (dimension ^2) of land/sea to generate wind captured by a line (dimension ^1) of windmills. These all concentrate solar power - but in a very lossy fashion. Hydro, for ecample, wasts much of the potential energy available as the rain hits the mountaintops "focussing" it into lakes at least half way down the mountain. Wave powere rewuires wint to drive the waves, then the waves to rool ove hunderds of miles to accumulate, before hitting the generator.

So the interesing part of this story is not really the tower, but the acres of greenhoses below and around it. This is a superb enegy concentrator device - and one, probably, with a lot of latent heat in the ground, so would run well after sunset. It is almost direct solar power - sun->hot air->power. If they can generate a lot of hot air, the tower is one way of converting it to electricity, but there may be others. But the point is that greenhouses can be economically constructed out of plastic film at a cost, I guess, 1% of the same area of solar cells. If they are only 10% as efficient at trapping the energy (and solar cells only run 5-15% efficeint), they are still winning by a large margin.

This idea is not actually very new. There was an SF story way back which proposed this sort of thing. Rather than build a tower, you just build a double walled cylinder out of the same polythene and inflate it with the hot air, (of which you have plenty) so that it lifts itself off. If it punctures, it will collapse very slowly (if at all, with many cells) and do little damage (because it willfall onto the greenhouses). Since the the tube is tranparent, a ring of lights round the base shining up into it will cause the whole thing to glow so that any pilot who flies into it must be truly blind.

There might be ecological consequneces - which need not be for the worse. The original SF story had the tubes puncturing the temperature inversion which causes AL's amoga and bringing a cooling draft to LA in the height of summer.