New Wind Turbine Design

        The cover article in the April 2010 Popular Science is about how GE’s latest design in wind turbines will attempt to leapfrog the rest of the industry.  (I don’t usually buy Popular Science because their articles usually do not cover a subject in sufficient depth to answer my questions.  But once in a while they have a cover piece that is just so intriguing I can’t resist.)  But before you look at this article, let me explain just what the GE people are probably trying to beat.  Right now, the best overall design is probably the Clipper, which is built in Cedar Rapids, Iowa.  This is not surprising, because this company was formed by a small group of entrepreneurs who each had wind turbine manufacturing experience going back 25 years or more. By pooling their patents and their capital, they hoped to finally build the kind of turbine which they had always wanted to build, but which no one had ever built. The design improvements they wanted were mainly these:

        First, scale it up large enough so that it’s up high where the wind is.  This is important because the amount of energy you get out of a turbine equals the cube of the wind speed.  That means that if by going higher you can get twice the velocity, then you get 8 times the output.  So they built a machine that has a blade “like a rotating football field” with its axle 350 feet above ground.

         Second, don’t generate AC directly off the turbine shaft.  Doing this leaves you with a shaft speed phase-locked to the power line frequency.  Better to make DC, letting the shaft speed vary with wind speed. Then use inverters to convert the DC to whatever AC the power line wants.

         Third, make the turbine maintainable.  Maintaining these machines is highly technical, and it takes a while to train a maintenance technician.  But with 300 foot ladders to climb every day, knees would start to wear out by age thirty-five.  You’d have to stop doing this work almost as soon as you got a good start.  Clipper’s answer is to put in an electric man-lift.

        Finally, don’t use one large generator--use four small ones.   If you use one big generator, then if it ever goes bad, you have to bring in a humongous crane to lift it down. 

        Clipper solves the problem like this:   Like most big wind turbines, Clipper has a gear-box to step up the very low shaft speed (15-60 rpm) to at least a few hundred rpm.  The Clipper gear-box has one bull gear turning four pinions.  The pinions are arranged in a circle, and each is permanently mounted in the gearbox with its own set of bearings and its own oil seal where the pinion shaft sticks out of the case.  Each pinion shaft is splined, and about 2 inches in diameter.  Each generator rotor just has a hollow shaft, internally splined, which fits over this arbor.  And since the generators use rotating fields using permanent magnets, there are no brushes either. The rotor is simply a collar that holds magnets, which fits over the arbor. The wiring is all in the stator, which slides over the rotor and is easily removable.  The stator housing has a flange on one end which bolts onto the gear box.  It’s light enough so that the built-in jib-crane can handle and it can be lowered to the ground with the built-in power winch.          

        But now GE is taking a different approach:   They eliminate the gear-box entirely by  mounting a single rotor wheel directly on the prop shaft, with diameter so large that the permanent magnet poles are moving through the stator windings fast enough even without a step-up in rpm.   The only part which might ever need replacing is the stator winding.  But this is made in small removable sections.  It seems to me that both the Clipper design and the new GE design would provide an ultra-low-maintenance machine.   As the wind turbine market matures and buyers begin to “price in” the advantage of maintainability, both of these designs are positioned to capture an increasing share of the market.

Crop Residue Boom

                                                

            According to a May 16^th article in the Des Moines Sunday Register, three large corporations are now collaborating in a research project aimed at cashing in on the coming boom in crop residue.  Archer Daniels Midland, Monsanto, and Deere & Co are trying to work out ways to harvest, transport, and process cornstalks into profitable products, such as ethanol, cattle feed,  or chemical feedstock.  Cellulosic ethanol is far past the stage of a starry-eyed vision, when major corporations start betting serious bucks on it.

            According to Paul Gallagher of Iowa State University, after leaving enough stover (crop residue) in the field to maintain soil fertility and protect against erosion, Iowa could still produce 26 million tons per year for industrial uses.  That equals 2 billion gallons of ethanol.  And as crop yields increase, stover yield will increase too.

            For many people, the term “alternative energy” conjures up visions of some hirsute Mother Earth News reading  hippie trying to live “off the grid” on his goat ranch in Idaho.  That was thirty years ago.  Today, large companies like GE are building huge multi-million dollar wind turbines, and the largest power companies on earth are buying and installing them, while Deere & Co, ADM, and Monsanto are trying to figure out how to run the country on cornstalks.  I’ve seen the future and it looks a lot like north central Iowa.  Interestingly, Texas and other western states who were the main energy suppliers in the oil boom may supply even more energy in the wind power boom.  (And wind won’t pollute the groundwater.)

            The ethanol industry may soon reach a stage of development where it becomes economically viable even without government mandates and subsidies.  But without those mandates and subsidies, this progress could not have happened. Yet from day one, we’ve heard complaints that none of these subsidies or mandates should have been used--that if technologies can’t pay their own way, then they must be a losers and the government shouldn’t be throwing money at them.  Of course, the complainers are morons and we should ignore them.

            Almost every successful industry passed through a phase where it was heavily subsidized.   Airplane manufacture has been subsidized by lucrative military contracts since WWI, and grain production has been propped up by federal price supports since the 1930s.  Yet these are our two most successful export industries.  And the recent bail out of the auto industry is only a tiny portion of the total subsidy this industry has received, if we consider that our highway system represents the largest single public expenditure in the history of the human race.

            Private enterprise’s most astounding accomplishment may be its ability to simultaneously lobby for more subsidies, while brainwashing us into believing that it’s not receiving them.  Europeans are less schizoid about it.  If they want something—they buy it.  And the public money spent is not a source of embarrassment--it's a source of civic pride.

Climate Change Report

The Wall Street Journal reported May 20 that the National Academy of Sciences has delivered to Congress an 869 page report on climate change .  Congress requested this report in 2008.  The report basically confirms the findings of the Intergovernmental Panel on Climate Change,  saying that climate change is occurring, is caused largely by human activities, and poses significant risks.  This update is much more alarming that previous reports.  The 2007 IPCC report said that sea levels might rise 1.9 feet by 2100. The new report say it would be as much as 6.5 feet. The report went on to urge bold steps to immediately reduce carbon use--either high taxes on carbon--or a cap and trade system.