PlanetWatch -- Alternative Energy, Energy Independence and Global Warming Reduction

Big Oil Says No Sugar in Your Gas Tank
U.S. oil companies are waging a stealth war against ethanol, funding studies that point up its negatives and subverting distribution at the pump.
Backlash Over the Biomass Boom
Outrage is developing over the folly of burning food crops for fuel, but politicians in the U.S. and Europe are, as usual, handing lavish subsidies to the farm bloc, while blocking imports with tariffs.
Guess Who's Pioneering an Automotive Revolution
Endowed with hydroelectric power and geothermal springs, Iceland plans to do away with $8/gallon gasoline and switch to hydrogen-powered autos.

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WIND POWER
Wind Machines the Envy of Leonardo
Could Today's Turbines Become Passé?

 

Today’s standard wind turbine design calls for three-bladed propellers, turning in a 300 ft. diameter, driving generators mounted on towers up to 300 feet tall. Groups of these devices located in high wind areas, mostly in the Southwest and West, can generate enough electricity, enough of the time, to be competitive with coal-fired generating plants at less than 10 cents per kilowatt hour.
     But these turbines are expensive to build. They also spark controversy among local residents, despite that they are, at least to some, quite beautiful. An important weakness is that they don't work when the wind is too light or too strong.

Winds Aloft Are More Reliable

Aviators and meteorologists know that "winds aloft" are stronger and steadier than surface winds and are therefore a tempting source of power. Between latitudes 30 and 50 degrees north, and above 3,000 feet, the wind is several times stronger than on the ground. Ground-based turbines obviously cannot reach these winds, but some entrepreneurs and engineers in the US and Italy are developing ingenious new ways to use this higher altitude wind for power, and the costs appear to be extremely promising. In fact, these new designs may be able to deliver electricity at 1-2 cents per kilowatt-hour, a fraction of ground-based wind turbine costs, and highly competitive with any other source of power.

But How to Reach the Winds Aloft?

Inventors have been thinking about this question for years, and have developed various designs for capturing the energy of upper winds. One such design looks like a twin-rotor helicopter that hovers in auto-rotation on a tether while the rotors run generators aboard and the power runs down a wire incorporated in the tether. This method has been shown to work, but is complex, expensive and conjures up images of helicopters crashing.
     There have been experiments with kites reeled out from spools that run generators on the ground; the same spool then reels the kite back in at a lower altitude's lesser winds, consuming much less power than was generated during the "outstroke". This approach works. But it requires multiple kites flying at the same time to produce a net positive output, making it complex to design, build and operate.

Enter a Technology Transfer of a Different Sort

A sport called kite-boarding has evolved from hang-gliding and wind-surfing. It allows a sailor on a "short-board" with foot straps to control very accurately a semi-circular, semi-rigid fabric kite overhead that tows the rider at high speeds on the surface of the water. It's more fun than water skiing, and it dispenses with the need for a speed boat. The key to the sport's growth beyond slightly crazed risk-takers to more ordinary athletes is the development of reliable controls for "powering up", steering and "de-powering" the kite at will.
     Environmentally-aware kite boarders began to see that their highly developed kites generate a lot of controllable power that might be used for other purposes, such as generating electricity. A group has started a company in Alameda, CA, called Makani Power, which can be visited at www.makanipower.com (makani = "wind" in Hawaiian). They are being stealthy about publicizing their approach, but a little information about them can be gleaned from public sources.

Google Gets Wind of It

Google learned of this company and has funded it with $10 million. Given Google's spectacular profitability, its brand acceptance, and its self-proclaimed "socially conscious" corporate culture, it is hard to imagine a better investor for Makani. Google is very conscious of the energy consumption of its uniquely large server farms; this is widely regarded as the reason for their locating an enormous data storage facility in The Dalles, OR, where hydro-power and water-cooling are cheap and plentiful — and so is wind, consistent enough to make nextdoor Hood River the kite boarding capital of the US.
     Most intriguing is how Makani plans to convert the power available from kites into meaningful amounts of usable power on the ground. In one variation they intend to build large individual kites fitted with a combination motor/generator. The motor is used for vertical take-off and to gain enough altitude for the wind to take over, whereupon the motor becomes a generator sending power down the tether to the ground. Through the control lines, the kite is made to describe high speed figure eights in the sky, greatly accelerating the relative wind over the generator/propeller, and increasing the power generated by the square of the increase in apparent wind speed.

Where Else But Italy

It is only appropriate that the country where Leonardo da Vinci first dreamed of flying machines centuries ago should continue the tradtion. One Italian design idea makes good sense. It involves building a large diameter "carousel-like" horizontal wheel that would rotate slowly in one direction and be connected through gearing to generators. Semi-rigid fabric kites attached at various points around the periphery of the carousel would drive the wheel. Each kite would be automatically powered up on one side of the wheel and de-powered on the other side, using standard control lines connected to a straightforward mechanical control system.
     It would be the same principle as an anemometer, writ large. It would overcome the need to transmit power along what is essentially a kite string that might be over 3,000 feet long.
     Preliminary analyses indicate that these designs could generate a great deal of power (ca. 1 to 100 megawatts per installation) in a relatively small space at reasonable cost. In fact, one engineer calculated that the restricted (for safety reasons) airspace near a nuclear power plant, could, if fitted with these sorts of wind generators, produce roughly the same amount of power as the nuclear plant itself.
     Many issues need to be resolved and many unknowns explored before these startling innovations can hope to replace today's wind turbines. But it is heartening to see how many original ideas are sparked by the world finally awakening to the hazard of continued reliance on hydrocarbons.
      - Douglas L. Ayer, PlanetWatch Editor, http://www.planetwatch.org