Now comes the big. A bold project has begun in the Australian Outback to build a huge tower that will capture the sun’s energy in a far more efficient way than conventional solar cells or windmills. It’s as simple as it is awesome.

Funneling Power to Earth

All wind power is really solar power, because the wind’s motion is stimulated by the sun.

The Solar Tower uses this combination in a focused and — well — breathtaking way.

Imagine a huge funnel. It’s almost flat at the edges and gradually curves over a distance of several miles until it reaches a tube in the center. The tube extends quite a distance down from the rest of the funnel. The tube is like a 3,280-feet long chimney.

You read that right: 3,280 feet — more than half a mile. When finished, this structure will be twice as long as the world’s highest skyscraper.

Now turn that funnel upside down and plant it in the Australian desert. That’s what Enviromission, Ltd. is planning to do. They’ve just acquired the land across which the funnel will spread, 25,000 acres to be precise.

The funnel is made of pieces of clear plastic, so the sun’s rays penetrate it all day long. As the rays penetrate the plastic, they heat the air below it.

Hot air tends to rise. In this case, rising means moving toward the center of the funnel. In the middle of the funnel lies the tube, through which all of the heated air seeks to escape.

The motion of air outside the tube is slow. Inside the tube, it’s very fast. How? Consider a bellows. A small squeeze causes a fast puff of air. The reason is that a large volume of air is trying to squeeze into a small opening. The only way that can work is for the air to move faster in the small opening.  The Solar Tower uses this same principle.

As air rises up the tube it accelerates to 35 MPH and propels 32 wind turbines, which in turn are used to generate electricity. In the desert, where sunlight is almost constant during the day, this provides a reliable source of power. (For nighttime use, some of the excess power will be diverted to huge arrays of batteries that are drained at night and recharged during the day.)

The Solar Tower has a huge advantage over conventional windmills: it generates its own wind.

The length of the tube and overall size of the system are of great importance. The relationship doesn’t scale in a linear fashion. By that, I mean that a Solar Tower with a tube five times as long isn’t five times as powerful. No, it’s 4,000 times more powerful.

A 650-foot test unit was built in Manzanares, Spain in 1981. It ran for seven years, steadily delivering 50 kilowatts. However, with oil prices at a mere $15 a barrel, there wasn’t much interest in building a larger one.

When constructed sometime after 2006, the 3,280 foot Solar Tower will generate 200 megawatts. At a typical home consumption of one kilowatt, this will power 200,000 homes and reduce the annual production of greenhouse gases by nearly a megaton.

Brad Collins, executive director of The American Solar Energy Society, confirms the advantages of the Solar Tower. He points out that it operates with maximum efficiency during the hottest times of day, exactly when air conditioning loads are highest.

Time Magazine even voted the Solar Tower one of the best inventions of 2002 (though it was older than that).

S. A. Sherif, a professor of mechanical engineering at the University of Florida, has authored papers on the Solar Tower and confirms its feasibility. Further, he says they “essentially produce energy for free.”

Now, of course, with oil at $57 a barrel and higher prices considered realistic, the economics have probably changed forever.

This isn’t some, uh, funnel-in-the-sky pipedream. As I stated earlier, an Australian public corporation, Enviromission, Ltd. has acquired $1 million to purchase a 25,000-acre sheep farm which will house the Solar Tower.

Still awaiting funding is the reported $500-750 million price of actually building the Solar Tower. However, that’s less than the cost of a typical conventional power plant, and it will require negligible maintenance. Further, Enviromission claims to have in hand two design proposals that will significantly reduce the construction cost.

The company claims to have signed a joint venture to develop several Solar Towers in China.

(Investment disclaimer: I am monitoring Enviromission for possible investment. However, it is neither a Transformational Technology nor a Special Situation purchase at this time. Stay tuned.)

Finally, let’s explore how the Solar Tower can completely meet humanity’s needs for electricity by 2050…

Today’s materials are limited in tensile strength. A tube length of 3,280 feet approaches that limit. However, in the decades to come, nanotechnology will enable production of materials that make today’s steel seem like paper by comparison.

Tubes many miles high will become possible. At that point, a handful of Solar Towers can be built on each continent and produce sufficient electricity to power everything on that continent.

It will be completely ecological, with no harmful emissions or side effects. It will run whenever the sun is out, continuously with very little maintenance. Huge arrays of batteries will gather and store excess electricity, and assure adequate distribution of power at night.

Fossil fuels will be relegated to the history books. Children won’t understand what all the hoopla was about. Tell that to your friends who think the end of oil means the end of civilization.

To your profitable future,

Jonathan Kolber
August 02, 2006

Solar Tower of Power was originally featured in the Penny Sleuth.