The historical and technical information in this section is derived from many sources. Information on developments since 1975 is based primarily on my personal experience with the U.S. Federal Wind Energy Program, my extensive reading (and editing) of wind energy journals and research reports over the last 25 years, my conversations with wind energy researchers, interactions with members of the wind energy community, and my personal view of wind power developments and of the wind industry. Opinions expressed here are my own, of course. --DMD
For human development to continue, we will ultimately need to find sources of renewable or virtually inexhaustible energy. It's difficult to imagine this, but even if we find several hundred or even thousand years of coal and natural gas supplies, what will humans do for the next 250,000 years or so after they are depleted? Even the most apparently "inexhaustible" sources like fusion involve the generation of large amounts of waste heat -- enough to place damaging stress on even a robust ecosystem like Earth's, at least for the organisms that depend upon stability of the system to survive. We are engaged in a sort of world-wide biological experiment, with our descendents as the subjects. Our present habits of energy use are shaping an entirely different earth than the one with which we are familiar. When these changes begin to be expressed, there will be no one to preserve the familiar and there's no guarantee that things will turn out the best for our particular species. Some have looked ahead and seen this. But they usually don't get much support from societies that are too busy trying to "make do" and that are rushing backwards into the future -- in other words, every society on earth. One of the areas that suffers because of this backward thinking is the development of renewable energy sources -- and the topic of this section: Wind Energy Conversion. There's a lot of underlying popular support for wind energy and the other renewables in the United States. But there's also a lot of apathy as well. We are blissfully sedated by low conventional energy prices and are gulping down the few remaining years of cheap natural gas and Mid East oil. As we do this, the inertia of global warming is inexorably building. What drives the continued development of mechanical devices like wind turbines in the face of this widespread lack of support? In the case of wind turbine technology, I suspect that part of the reason for persistence of this vision is how accessible wind turbines are to the understanding. They are personal in a way that almost no other form of power generation is. This "personal" scale has been both the blessing and the curse of wind power development. The field tends to attract people who are committed, creative, and passionate. It also attracts a few people who are a little too much of all of those things, to the point that sometimes the grounding of reality is lost. Both of these tendencies will be evident in this brief history of wind power development. Wind power will probably succeed or fail based on the ability or inability of its proponents to bank the fires of "Romance" and focus on defining wind generation's role as a practical alternative to conventional generation sources. Wind energy conversion is a fascinating field to study, if only because its past has been so checkered and its exact future is so uncertain. Unlike the aerospace industry, the computer industry, and almost any other successful industry you can name, wind energy -- the leading mechanically-based renewable energy for much of man's history -- has never made anyone rich for long. But unlike many of these other industries, it has been around for thousands of years. It's a technology that has been reinvented numerous times. We are left with the promise and the drive to succeed despite daunting (and sometimes puzzling) obstacles.
Figure 1a. Maximum efficiency of a "drag" device is obtained when the collector is pushed away from the wind, as is a simple, drag-type sail boat. In this Persian panemone design, the rotor can only harvest half of the wind striking the collection area. The panemone is one of the least efficient, but most commonly reinvented (and patented) wind turbine concepts.
The history of wind power shows a general evolution from the use of simple, light devices driven by aerodynamic drag forces; to heavy, material-intensive drag devices; to the increased use of light, material-efficient aerodynamic lift devices in the modern era. But it shouldn't be imagined that aerodynamic lift (the force that makes airplanes fly) is a modern concept that was unknown to the ancients. The earliest known use of wind power, of course, is the sail boat, and this technology had an important impact on the later development of sail-type windmills. Ancient sailors understood lift and used it every day, even though they didn't have the physics to explain how or why it worked. The first windmills were developed to automate the tasks of grain-grinding and water-pumping and the earliest-known design is the vertical axis system developed in Persia about 500-900 A.D. The first use was apparently water pumping, but the exact method of water transport is not known because no drawings or designs -- only verbal accounts -- are available. The first known documented design is also of a Persian windmill, this one with vertical sails made of bundles of reeds or wood which were attached to the central vertical shaft by horizontal struts (see Figure 1a). A 19th Century American approximation of thispanemone device is shown at the left (Figure 1b). Grain grinding was the first documented wind mill application and was very straightforward. The grinding stone was affixed to the same vertical shaft. The mill machinery was commonly enclosed in a building, which also featured a wall or shield to block the incoming wind from slowing the side of the drag-type rotor that advanced toward the wind. Vertical-axis windmills were also used in China, which is often claimed as their birthplace. While the belief that the windmill was invented in China more than 2000 years ago is widespread and may be accurate, the earliest actual documentation of a Chinese windmill was in 1219 A.D. by the Chinese statesman Yehlu Chhu-Tshai. Here also, the primary applications were apparently grain grinding and water pumping.
Figure 1b. A 19th-century American knock-off of the Persian panemone that probably made a wonderful clothes dryer.
Figure 2. Water Pumping Sailwing Machines on the Island of Crete
One of the most scenic and successful applications of windpower (and one that still exists), is the extensive use of water pumping machines on the island of Crete. Here, literally hundreds of sail-rotor windmills pump water for crops and livestock.
Figure 3. An early sail-wing horizontal-axis mill on the Mediterranean coast.
The first windmills to appear in western Europe were of the horizontal-axis configuration. The reason for the sudden evolution from the vertical-axis Persian design approach is unknown, but the fact that European water wheels also had a horizontal-axis configuration -- and apparently served as the technological model for the early windmills -- may provide part of the answer. Another reason may have been the higher structural efficiency of drag-type horizontal machines over drag-type vertical machines, which (remember) lose up to half of their rotor collection area due to shielding requirements. The first illustrations (1270 A.D.) show a four- bladed mill mounted on a central post (thus, a "postmill") which was already fairly technologically advanced relative to the Persian mills. These mills used wooden cog-and-ring gears to translate the motion of the horizontal shaft to vertical movement to turn a grindstone. This gear was apparently adapted for use on post mills from the horizontal-axis water wheel developed by Vitruvius. As early as 1390, the Dutch set out to refine the tower milldesign, which had appeared somewhat earlier along the Mediterranean Sea (Figure 3, above left). The Dutch essentially affixed the standard post mill to the top of a multi-story tower, with separate floors devoted to grinding grain, removing chaff, storing grain, and (on the bottom) living quarters for the windsmith and his family. Both the post mill and the later tower mill design had to be oriented into the wind manually, by pushing a large lever at the back of the mill. Optimizing windmill energy and power output and protecting the mill from damage by furling the rotor sails during storms were among the windsmith's primary jobs.
Figure 4. An operating Dutch windmill (1994) that features leading edge airfoil sections (at top right). The mechanism used to turn the rotor into the wind and the windows of the first-floor living quarters are easily seen.
A primary improvement of the European mills was their designer's use of sails that generated aerodynamic lift (see Figure 4 at the left). This feature provided improved rotor efficiency compared with the Persian mills by allowing an increase in rotor speed, which also allowed for superior grinding and pumping action.The process of perfecting the windmill sail, making incremental improvements in efficiency, took 500 years. By the time the process was completed, windmill sails had all the major features recognized by modern designers as being crucial to the performance of modern wind turbine blades, including 1) camber along the leading edge, 2) placement of the blade spar at the quarter chord position (25% of the way back from the leading edge toward the trailing edge), 3) center of gravity at the same 1/4 chord position, and 4) nonlinear twist of the blade from root to tip (Drees, 1977). Some models also featured aerodynamic brakes, spoilers, and flaps. The machine shown in Figure 4 (which was operating with two of its buddies pumping water about one meter up from one irrigation pond to another in the Netherlands in 1994) features leading edge airfoil sections. These mills were the "electrical motor" of pre-industrial Europe. Applications were diverse, ranging from the common waterwell, irrigation, or drainage pumping using a scoop wheel (single or tandem), grain-grinding (again, using single or multiple stones), saw-milling of timber, and the processing of other commodities such as spices, cocoa, paints and dyes, and tobacco. While continuing well into the 19th century, the use of large tower mills declined with the increased use of steam engines. The next spurt of wind power development occurred many thousands of miles to the west.
Figure 5. A steel-bladed water pumping windmill in the American Midwest (late 1800's)
Role of Smaller SystemsFor hundreds of years, the most important application of windmills at the subsistence level has been mechanical water pumping using relatively small systems with rotor diameters of one to several meters. These systems were perfected in the United States during the19th century, beginning with the Halladay windmill in 1854, and continuing to the Aermotor and Dempster designs, which are still in use today. The first mills had four paddle-like wooden blades. They were followed by mills with thin wooden slats nailed to wooden rims. Most of these mills had tails to orient them into the wind, but some were weather-vaning mills that operated downwind of the tower. Speed control of some models was provided by hinging sections of blades, so that they would fold back like an umbrella in high winds, an action which reduced the rotor capture area to reduce thrust. The most important refinement of the American fan-type windmill was the development of steel blades in 1870 (Figure 5). Steel blades could be made lighter and worked into more efficient shapes. They worked so well, in fact, that their high speed required a reduction (slow-down) gear to turn the standard reciprocal pumps at the required speed. Between 1850 and 1970, over six million mostly small (1 horsepower or less) mechanical output wind machines were installed in the U.S. alone. The primary use was water-pumping and the main applications were stock watering and farm home water needs. Very large windmills, with rotors up to 18 meters in diameter, were used to pump water for the steam railroad trains that provided the primary source of commercial transportation in areas where there were no navigable rivers. In the late 19th century, the successful "American" multi-blade windmill design was used in the first large windmill to generate electricity.
The most obvious influence on 20th century wind power was the increasing use of electricity. But this started with a look to the past.First Use of Wind for "Large-Scale" Generation of Electricity The first use of a large windmill to generate electricity was a system built in Cleveland, Ohio, in 1888 by Charles F. Brush. The Brush machine (shown at right) was a postmill with a multiple-bladed "picket-fence" rotor 17 meters in diameter, featuring a large tail hinged to turn the rotor out of the wind. It was the first windmill to incorporate a step-up gearbox (with a ratio of 50:1) in order to turn a direct current generator at its required operational speed (in this case, 500 RPM.) Despite its relative success in operating for 20 years, the Brush windmill demonstrated the limitations of the low-speed, high-solidity rotor for electricity production applications. The 12 kilowatts produced by its 17-meter rotor pales beside the 70-100 kilowatts produced by a comparably-sized, modern, lift-type rotor. In 1891, the Dane Poul La Cour developed the first electrical output wind machine to incorporate the aerodynamic design principles (low-solidity, four-bladed rotors incorporating primitive airfoil shapes) used in the best European tower mills. The higher speed of the La Cour rotor made these mills quite practical for electricity generation. By the close of World War I, the use of 25 kilowatt electrical output machines had spread throughout Denmark, but cheaper and larger fossil-fuel steam plants soon put the operators of these mills out of business. By 1920, the two dominant rotor configurations (fan-type and sail) had both been tried and found to be inadequate for generating appreciable amounts of electricity. The further development of wind generator electrical systems in the United States was inspired by the design of airplane propellers and (later) monoplane wings.
Figure 6. The Brush postmill in Cleveland, Ohio, 1888. The first use of a large windmill to generate electricity. Note the man mowing the lawn at lower right.
Small System PioneersThe first small electrical-output wind turbines simply used modified propellers to drive direct current generators. By the mid-1920's, 1 to 3-kilowatt wind generators developed by companies like Parris-Dunn and Jacobs Wind-electric found widespread use in the rural areas of the midwestern Great Plains. (A 3-kilowatt Jacobs unit is shown at right, being adjusted by a cigarette-puffing M.L. Jacobs at Rocky Flats, Colorado in 1977.) These systems were installed at first to provide lighting for farms and to charge batteries used to power crystal radio sets. But their use was extended to an entire array of direct-current motor-driven appliances, including refrigerators, freezers, washing machines, and power tools. But the more appliances were powered by the early wind generators, the more their intermittent operation became a problem. The demise of these systems was hastened during the late 1930s and the 1940s by two factors: the demand of farmsteads for ever larger amounts of power on demand, and the Great Depression, which spurred the U.S. federal government to stimulate the depressed rural economies by extending the electrical grid throughout those areas. A lot is made of this development and how horrible it was for the government to intervene. (At this point in most wind energy documentaries, there's a plaintive whine of a harmonica and a shot of a rusting wind turbine hulk.) But I doubt the farmers who were helped by the new electrical grids would share this feeling. And the growing demand for electrical power created by the wind generator, combined with the inability of the technology to adapt, helped make the situation inevitable. The early success of the Midwest wind turbines actually set the stage for the possibility of more extensive wind energy development in the future. While the market for new small wind machines of any type had been largely eroded in the United States by 1950, the use of mechanical and electrical system continued throughout Europe and in windy, arid climates such as those found in parts of Africa and Australia.
Figure 7. M.L. Jacobs adjusting the spring-actuated pitch change mechanism on a Jacobs Wind-electric in 1977.
"Bulk" Power from WindThe development of bulk-power, utility-scale wind energy conversion systems was first undertaken in Russia in 1931 with the 100kW Balaclava wind generator. This machine operated for about two years on the shore of the Caspian Sea, generating 200,000 kWh of electricity. Subsequent experimental wind plants in the United States, Denmark, France, Germany, and Great Britain during the period 1935-1970 showed that large-scale wind turbines would work, but failed to result in a practical large electrical wind turbine. The largest was the 1.25 megawatt Smith-Putnam machine (Figure 8, at right), installed in Vermont in 1941. This horizontal-axis design featured a two-bladed, 175-foot diameter rotor oriented down-wind of the tower. The 16-ton stainless steel rotor used full-span blade pitch control to maintain operation at 28 RPM. In 1945, after only several hundred hours of intermittent operation, one of the blades broke off near the hub, apparently as a result of metal fatigue. This is not surprising considering the huge loads that must have been generated in a structure that had a lot in common with a gigantic rotating erector set.
Figure 8. Palmer Putnam's 1.25-megawatt wind turbine was one of the engineering marvels of the late 1930's, but the jump in scale was too great for available materials.
European DevelopmentEuropean developments continued after World War II, when temporary shortages of fossil fuels led to higher energy costs. As in the United States, the primary application for these systems was interconnection to the electric power grid. In Denmark, the 200 kW Gedser Mill wind turbine operated successfully until the early 1960s, when declining fossil-fuel prices once again made wind energy made uncompetitive with steam-powered generating plants. This machine featured a three-bladed upwind rotor with fixed pitch blades that used mechanical windmill technology augmented with an airframe support structure. The design was much less mechanically complex than the Smith-Putnam design. In fact, it was not that far removed from Poul La Cour's 1920-era windmill (a fact that worked to its advantage.)
Figure 9. Yes, that's an airframe holding together the three blades of the "Gedser Mollen." Fiberglass later eliminated this design requirement.
In Germany, Professor Ulrich Hutter developed a series of advanced, horizontal-axis designs of intermediate size that utilized modern, airfoil-type fiberglass and plastic blades with variable pitch to provide light weight and high efficiencies. This design approach sought to reduce bearing and structural failures by "shedding" aerodynamic loads, rather than "withstanding" them as did the Danish approach. One of the most innovative load-shedding design features was the use of a bearing at the rotor hub that allowed the rotor to "teeter" in response to wind gusts and vertical wind shear. Hutter's advanced designs achieved over 4000 hours of operation before the experiments were ended in 1968.Post war activity in Denmark and Germany largely dictated the two major horizontal-axis design approaches that would emerge when attention returned to wind turbine development in the early 1970s. The Danes refined the simple, fixed pitch, Gedser Mill design, utilizing advanced materials, improved aerodynamic design, and aerodynamic controls to reduce some of its shortcomings. The engineering innovations of the light-weight, higher efficiency German machines, such as a teeter hinge at the rotor hub, were used later by U.S. designers. The development of modern vertical-axis rotors was begun in France by G.J.M. Darrieus in the 1920s. Of the several rotors Darrieus designed, the most important one is a rotor comprising slender, curved, airfoil-section blades attached at the top and bottom of a rotating vertical tube. Major development work on this concept did not begin until the concept was reinvented in the late 1960s by two Canadian researchers. U.S. efforts with the Darrieus concept at Sandia National Laboratories began after the 1973 oil embargo, with the entry of the U.S. Federal Wind Energy Program into the cycle of wind energy development.
Figure 11. Proposed GE wind turbines on the coast of Long Island, NY (late 1970's)
Making Wind a Federal Case In the United States, the federal government's involvement in wind energy research and development began in earnest within two years after the so-called "Arab Oil Crisis" of 1973. Despite the speed with which it was initiated and began to show results, this program ultimately proved to be largely ineffective because of the interference of political factors and the withdrawal of financial support before success could be achieved. Federal research and development activities resulted in the design, fabrication, and testing of 13 different small wind turbine designs (ranging from 1kW to 40kW), five large (100kW - 3.2MW) horizontal-axis turbine (HAWT) designs, and several vertical axis (VAWT) designs ranging from 5 to over 500 kW. The approach of this program borrowed much from the methods used to develop military aircraft, with first the Energy Research and Development Administration (ERDA) and then the U.S. Department of Energy (DOE) selecting subcontractors to build and test machines that would be commercialized; presumably by the subcontractors. Most of the funding was devoted to the development of multimegawatt turbines, in the belief that U.S. utilities would not consider wind power to be a serious power source unless large, megawatt-scale "utility-scale" systems were available. Not-withstanding the unusual case of the California wind farms (see below), recent events (such as the development of 1+ megawatt giants in Europe) have shown that this view was fundamentally correct. Our discussion will resume, after a short diversion . . .
Figure 12. "Tower? What Tower?" Hard core Darrieus advocates deny that this machine has a tower, perhaps because eliminating the tower was supposed to be an advantage of the design over HAWTs.
Pushing VAWTsIn some respects, the development of vertical axis technology serves to illustrate the difficulties of government-sponsored development programs most effectively. By the standards usually used by federal managers to evaluate program achievement, the Darrieus program was an unqualified success. Development in the U.S. progressed in an orderly manner from 5, 10, and 17-meter experimental machines to a 17-meter machine commercialized by FloWind that used much of the Sandia technology. Many high quality government reports were published. But--beyond supporting one remnant company from the 1980's wind farm boom--a real market for this technology has never emerged. The largest U.S. Darrieus machine is a 34-meter, variable-speed testbed (left), developed by Sandia Laboratories, and operated at the USDA Agricultural Resarch Station in Amarillo, Texas to provide experimental data. In Canada, development reached the multi-megawatt scale, with the 4-MW Project Eole turbine on Magdalen Island in the St. Lawrence River. Recent experimental developments for Darrieus systems center around the use of pultruded fiberglass rotors because of the high cost of extruded aluminum. The flexibility of this material has forced designers away from the "troposkein" shape of the earlier machines (from the Greek "turning rope") to use an "extended height-to-diameter" (EHD) shape that limits blade flexure and increases stiffness. So far, results are mixed.
Figure 12. Deadly winds build in the Rockies west of an early fiberglass-bladed Darrieus wind turbine at the Rocky Flats Test Center, 1981.
The lopsided pear shape of the Tumac prototype (at left) illustrates the structural problems that have been a problem for fiberglass Darrieus designs. This particular machine failed to survive the first moderately high winds it faced.Some straight-bladed vertical axis turbines of the cycloturbine, giromill, and "H" turbine configurations were developed in the 1970s in the United States and Great Britain and into the 1990s in Germany. None of the straight-bladed designs has proved to be commercially successful because of the problems encountered in handling cantilevered rotor loads with struts and structural members that cause large amounts of aerodynamic drag.
Figure 13. The 200kW MOD-0A wind turbine at Clayton, New Mexico was a qualified success for NASA and DOE Figure 14. In the words of one exasperated federal program manager, the 2-megawatt General Electric MOD-1 machine was built "hell-for-stout." Unpredicted low frequency sound emissions resonating in the many homes scattered through hills and valleys close to the installation killed the project.
"Hell-for-Stout"Beginning with the 100kW MOD-0 installed at NASA's Plum Brook Ohio facility in 1975, the U.S. program rapidly moved through several generations, including the MOD-1 and the 100-meter diameter MOD-2 wind turbines (see below.) Unfortunately, the program was burdened by an early error that took four years to overcome. In 1974, perhaps expecting to reproduce the success of U.S. rocketry development by copying advanced German designs, NASA engineers turned to Ulrich Hutter's blueprints for answers. While borrowing Hutter's two-bladed, downwind rotor configuration for their early designs, they failed to note the importance of the fact that Hutter's machines featured teetering hubs--now known to be essential for reducing dynamic loads created by tower shadow in two-bladed machines. NASA engineers were astounded by the huge dynamic loads the first (MOD-0) machine developed whenever a blade entered the "dead" space behind the tower (which was also much beefier and blocked more wind than Hutter's). And it took several years of engineering studies, responding to outraged Congressional inquiries (from none other than Barry Goldwater), and other diversions to figure out what was going on and switch to an upwind, teetered hub configuration. The rigid hub NASA turbines (with a probable useful machine life measured in months) none-the-less served as useful stand-ins for demonstration projects until "real" machines arrived in the early 1980's. The program's biggest early success was the operation of four MOD-OA 200 kW machines by U.S. utility companies (Figure 13.) The moniker "real machine" did not apply to the MOD-1 (Figure 14, at left), the program's first attempt at a megawatt-scale system. Because it was designed before the problems with the MOD-0 were understood, the design was a lame duck even before acoustic resonance problems (themselves aggravated by the lack of a teetering hub) scuttled the first and only installation at Boone, North Carolina.
Figure 14. The 3-megawatt, 100-meter diameter MOD-2 operated by PG&E in Solano, California was the most successful private operation of a multi-megawatt wind turbine until the MOD-5B in Oahu, Hawaii.
A "Real" Machine?The first "real" NASA wind turbine was the 100-meter diameter MOD-2. Three of these machines operated for several years at a site overlooking the Columbia River in the 1980's, providing valuable engineering data and helping to pinpoint design weaknesses. Others operated at Solano, California (left) and near Medicine Bow, Wyoming. The MOD-2 was an inevitably flawed experimental machine because of the huge technological leap it represented from the MOD-1. This provided detractors with an easy target for criticism. By 1981, the detractors of the Federal program had succeeded in getting most of the development activity scuttled, just when things were poised to get better. Lessons learned on the MOD-2's were incorporated in the 3.2-megawatt MOD-5B, a 100+ meter behemoth that was still operating (not without problems) on the Island of Oahu, Hawaii in 1997.
Figure 15. The Enertech 44/15 in 1981 at Rocky Flats. Over 600 of these turbines (up-rated to 40 or 60kW) were operating in California Windfarms by 1983. It has recently been value-engineered to produce the Atlantic Orient 15/50 machine.
Small "Wonders"A small machine development effort was belatedly started in 1976, when a federal test center established at Rocky Flats, Colorado found that available machines were neither properly-sized, nor reliable enough, to do the jobs envisioned by federal application studies. Within four years, 13 wind turbine designs in five application-based size-ranges were procured, designed, fabricated, and tested:
1-2 kW High Reliability
4kW Small Residential
8 & 15 kW Residential and Commercial
40kW Business and Agricultural
Successes of this program included 1-3kW and 6kW small turbines commercialized by Northern Power Systems and still being sold for remote power uses, and a three-bladed 40-60kW machine installed by the hundreds in California windfarms by Enertech (at left). But, in 1981, the biggest successes of the federal program were not measured in hardware, but in the number of designs shown to be unfeasible and in the amount of expertise developed in both the federal programs and in their private industry subcontractors. The ground had been laid for success. But this was not to happen. Federal development efforts were prematurely scuttled by the Reagan Administration, when the banking and investment industry threw its lobbying support behind wind industry efforts to obtain huge energy tax credits. There was no time for reliable hardware to evolve from exploratory developments. There was no time for a "simpler is better" philosophy resulting from the small turbine development program at Rocky Flats to permeate and rejuvenate the large machine design efforts at NASA. While the tax credits seemed to some to be an evolutionary development, they actually amounted to a complete redirection of U.S. energies. Planning for this re-direction was left to administration officials who thought that wind turbines were a mature technology that needed no further development. And who believed the over-optimistic claims of investment-hungry wind businesses that cost-effective and reliable designs were already available.
Figure 16. Early on, the federal program had a fatal attraction to "simple," but dynamically complex designs, like UTRC's composite flexbeam rotor. The pultruded fiberglass blade fabrication technique was a "keeper" however and was later used by Bergey Windpower in its 1.5 and 10-kilowatt designs.
A Blown OpportunityIn the seven years between 1974 and 1981, the U.S. Federal Wind Energy Program was an extraordinarily efficient and successful government research and development activity. Thirteen small systems, several vertical axis and innovative systems, and four large wind turbine designs were developed and tested in that brief period. In addition, two promising intermediate scale turbines -- which could have given the U.S. a huge technological lead -- were on the drawing board and ready for development. All of this was lost. In the subsequent seven years between 1981 and 1988 -- despite hundreds of millions of federal tax credits -- only four new wind turbine designs were developed in the U.S. All but one (the Bergey 10kW, which didn't benefit from the credits) were based on spin-offs of technology developed by companies supported by the previous federal development effort. And even the Bergey relied for its flexible blades on a pultrusion manufacturing technique (left) developed under government sponsorship. Finally, in 1989, the federal program -- now managed by NREL -- seized an opportunity provided by the Bush administration and resumed under-funded value engineering of some of the early 1980's designs. Some of the results can be seen at the Web site of the National Wind Technology Center.
Figure 17. The GROWIAN wind turbine. Like the MOD-2, this experimental machine was a laughing stock of the wind energy world in the 1980's as small 100kW wind turbines became the darlings of the investor community.
European Development ProgramsIn Europe, government multi-megawatt machine development programs took longer to start, but were even less successful from a commercial standpoint. The multi-megawatt GROWIAN turbine developed in Germany is pictured at the left (Figure 17). By the early 1990's, most of the experimental multimegawatt machines developed in Germany, Sweden, and other countries were no longer operating and efforts at the network of European wind energy research laboratories had shifted to basic and applied research, the development of standards, and certification testing programs. The proper role of government in wind energy research and development is a matter of continuing controversy. There has been a tendency by some commentators to lose sight of the fact that no successful wind energy project -- in any country -- has been conducted without some form of government intervention in the form of financial, technical, or regulatory support. This is really no different than any other kind of power production facility. The myth that somehow the windfarm development of the 1980's was due primarily to "private enterprise" has even been expressed by people sitting right in the middle of hundreds of European-manufactured wind turbines -- every one of them supported by U.S. and foreign taxpayers and dependent upon "sweet-heart" government-enforced power purchase requirements. But that's another story. The fact remains that painstakingly-developed R&D programs were gutted in the early 1980's to provide funding for energy tax credits, which failed to provide sufficient impetus for broad-based private wind turbine technology development in the U.S. In the 1990's, a wiser U.S. industry has encouraged renewed modest funding for research and development, primarily in programs managed by the National Wind Technology Center, operated by the National Renewable Energy Laboratory at a site just outside Boulder, Colorado.
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