Slashdot Mirror

Why would tracking be slow? Parallax being what it is? As long as the mirror is tracking targets within the same quadrant of the sky, it should be able to switch fast enough.

As for modulation, I think you are making unstated assumptions about reflectivity and switching speeds. How are you imagining the focus to be shifted and reflectivity varied? Mylar held by variable stays, held taught by photion pressure, for example? Easy, point a big dish at a little dish for a two reflector system, and your traverse speeds (governed by mass) and modulation speed (also, to some extent governed by mass, depending on the method) are dramatically reduced, as now you only must move the smaller reflector.

I know very well about solar concentration with mirrors. A reflector array in the L1 would have the potential to extend the day cycle of a solar collection site.

http://www.sbp.de/en/html/solar/dish-stirling.html

You forget about the fact that the ground underneath the collector acts as a heat sink and enables the tower to continue to run throughout the night(although at a *much* lower efficiency). It's its own heat-sink, in effect. They can greatly mitigate this, though, by placing heat absorbing materials in the ground as well(oil or water filled pipes has been suggested) Compared to a tower filled with molten salt, this is backyard-engineering simple. You could even place solar arrays underneath the main canopy/surface to collect even more of the energy. (me, I'd be tempted to pave it with blacktop to increase the heat absorption - lol)

http://www.sbp.de/de/fla/contact/download/The_Solar_Updraft.pdf
This is the best paper that I can find for free(no access idiocy/cost) about it.

It really is a zero-tech approach to power that can work 24 hours a day. It's also very inexpensive relative to the KW generated. But it does require absolutely huge areas of land. Then again, a square mile is hardly a blip out in Arizona or Nevada.

"Continuous 24 hours-operation can be achieved by placing tight water-filled tubes orbags under the roof. The water heats up during day-time andreleases its heat at night. " http://www.sbp.de/de/fla/contact/download/The_Solar_Updraft.pdf This was tested in La Mancha in the 80's.

the other iter members went ahead and cleared the blockade that has been laid since bush reentered iter.

The first post is completely wrong about it being a "threat" to China or anyone else. China *wants* the reactor to be built in the EU instead of Japan. So does the other ITER member, Russia. If the US hadn't opposed the french location and induced Japan to resist it more strongly despite the odds, the project would have went ahead some time ago.

Unlike nuclear fission power, fusion power has enough fuel available that it could potentially supply all of the world's energy demand for thousands and even millions of years and it doesn't produce nearly as much dangerous nuclear waste nor can fusion power be used as a disguise for a nuclear weapons program. The amount of deuterium for fusion is practically unlimited - 1 kg of ordinary water contains about 1 gram of heavy water which contains deuterium instead of common hydrogen. It seems that, unlike in the past decades where the researchers said "Fusion Power will be ready soon, there are just some issues which we expect to have resolved soon if we get more money." it now is "We have the issues resolved and could build a reactor that can sustain a fusion reaction and give a net output of energy. Now we just need the money to build a reactor sufficiently large so we can prove and make sure that it works like we think it does."

Of course with such a pretty-much-as-cheap-as-coal technology available as the solar tower that is so simple in its function, provides steady uninterrupted power, and about which relevant laws of nature are so well understood that it is guaranteed to work, it may be questionable if we actually have a reasonable need for fusion power on earth. Of course, solar towers need a sunny place to build them in order to be efficient and they don't need any high-tech to build either, which may well be the reason why the west has mostly stopped supporting the technology. Solar tower for large scale electricity production can be build with just basic construction materials like mostly cement, steel and glass(which is sand) and with labor. Ideal if you want to help many poor countries, but inadequate if you want them to stay poor and dependent to keep exploiting them.

Very interesting concept thank you for posting it (hadn't heard about it before).

## Links for the interested ##
The Australian company involved: http://www.enviromission.com.au/index1.htm
The designers/inventors Schlaich Bergermann and Partner: http://www.sbp.de/en/fla/index.html
(choose Projects | Solar Energy | All Solar-Power Plants, first and last pictures take you to the two solar tower projects)
A recent Wired news item on the subject: http://www.wired.com/news/technology/0,1282,54917, 00.html

Please mod parent up as interesting :)

In Australia, in 2005 is the completion date of a solar power tower, they, sbp of Germany are building.

In short, the sun heats the air at the 7km diameter base 'glasshouse'.
This hotair rises, up the 1km tunnel, spinning turbines as it moves.

it's cool. (and hot)

Here another article I found.

So with more advances like this, we will get in the right direction ! :-)

Here is a link to the designers of the original plant in Spain. Under "Index - Solar Power Plants" you will find more on both the Solar Chimney and a Dish/Stirling combination.