Modern wind turbines depend on technology developed for airplanes and rockets, but they trace their ancestry at least as far back as the windmills of medieval Europe. For some six hundred years, windmills grew in mechanical sophistication, but their rotors all had four blades.
Most of them, especially later in the period, were large structures that protected the mechanism and provided storage. That’s not what windmills looked like on the American prairie.
Daniel Halladay of Connecticut invented a new way to use wind power to pump water in 1854. His design still had four blades, but otherwise it looked very different. Instead of being mounted on a large building, it worked at the top of a simple scaffolding that was much less expensive to build.
A tail on the rotor made it entirely self-governing. That is, no human intervention was ever required to orient it to the wind.
His design also enabled the windmill to regulate its own speed. A windmill rotating too fast in a very strong wind can easily break apart. That Halladay’s windmills could adjust their speeds automatically made them even more low-maintenance.
There turned out to be a huge marked for these sturdy and inexpensive machines. Farms and cattle ranches not located by a river required water pumped from underground. So did railroads. Other manufacturers eventually eclipsed Halladay’s company.
Eventual improvements to his original design included using more than four blades and building the entire structure from galvanized steel instead of wood. By 1970, the various manufacturers had installed more than six million windmills in the United States alone. Most of them were one horsepower or less to meet the needs of one small farm or one part of one.
Wind power for electricity
By the late nineteenth century, this American design had found an entirely new use. In 1888 Charles F. Brush of Cleveland, Ohio, built a very large windmill with a multiple-blade rotor almost 56 feet in diameter (as opposed to as little as four feet for some of the smaller machines) to generate electricity. It produced 12 kilowatts of power.
Eventually, the Halladay design had to be abandoned for electricity production. The aerodynamic principles of the best European tower mills proved superior for that application. Danish engineer Poul la Cour built a wind-driven electric generator that our than doubled Brush’s output. Unfortunately, steam plants that required burning fossil fuels could make larger and cheaper plants and put la Cour out of business.
The idea of using the wind to generate electricity had been born, however, and would not die in infancy. The new field of aeronautics demonstrated that airplane propellors could make better wind turbines than any traditional windmill blade design. The extension of the power grid to American rural areas in the 1930s and 40s put a temporary crimp on wind power as it offered farmers more power at a cheaper cost.
Research on wind turbines continued, however. Economics made wind turbines more feasible to use in parts of Australia, Asia, Africa, and for a while after World War II even in Europe. As a result of the Arab oil embargo of 1973, even the American government became interested in exploring the development of wind-generated electricity. Unfortunately, a series of failed designs led the Reagan administration to scuttle further funding for development–temporarily as it turned out. Meanwhile, research continued in Europe, and American industry succeeded in getting renewed government funding in the 1990s
Modern wind turbines usually have rotors with three blades. Instead of wood or steel, they’re made of much lighter materials, like fiberglass or plastic. Commercial wind power depends on very large rotors, with single blades up to 125 feet long. In fact, the blades being developed for a large-scale offshore wind farm due for completion in 2015 will be so long that a 747 passenger jet will fit comfortably between them. It appears that the point of diminishing returns has been reached in terms of ever larger rotors.
Today’s researchers are looking into a large assortment of alternative designs. If the history of technology is any indication, many or most of them will look very foolish in retrospect, but one or more will lead to the next leap forward in wind power. The next generation of wind farms will produce massive amounts of electricity for the grid. As currently configured, the grid will not be able to handle it. It must be completely redesigned and rebuilt before then.
Meanwhile, the now traditional rotors informed by airplane propellors and rocket science still work very well for home use. Millions of homes, farms, and small businesses can take advantage of a proven technology.
There’s no need to wait until emerging technologies enable large-scale wind generation and a grid capable of moving it from where it’s made to where it’s needed.
Electricity from the existing grid is both expensive and dirty; half of todays electricity comes from coal, and burning other fossil fuels provides another quarter of it.
Buying some combination of wind and solar generators for home use is a great investment. It will pay for itself in lower or non-existent electricity bills in just a few years. Both clean and economical electricity from the grid will not happen for years afterward. Check into alternative energy for your home or business right away!
Sources include Illustrated History of Wind Power Development.
Halladay-model windmill: Advertisement from mid-19th century. Public domain.
Wind farm: © Copyright Stephen Craven and licensed for reuse under this Creative Commons Licence.
Rooftop home wind turbine: Some rights reserved by tswind.