www.floridahydro.com/Technology.htm
Florida Hydro's Technology Florida Hydro is capable of converting the tremendous power of rushing ocean currents into usable electricity and hydrogen through the use of its energy device, the Open-Center Turbine system. The Open-Center Turbine is a submerged wheel of blades anchored to the sea floor that works to produce electricity in a manner similar to a windmill. The key difference is that the Open-Center Turbine is located 200 feet underwater instead of on land.
The technology is innovative in that engineering tests show it to be the first system capable of harnessing ocean currents cost-effectively. This is due to a number of design advantages that make it a breakthrough technology for exploiting ocean energy to produce clean electricity. The Open-Center Turbine was developed specifically for the dynamics of the Gulf Stream current.
Gulf Stream is an underwater ocean current that flows along the edge of the Florida coastline at a rate of 30 million cubic meters per second. The Gulf Stream flows constantly at 45 knots through a narrow, predictable channel, and because sea water is 832 times denser than air, the current has more kinetic energy than a 140-mph wind. Thus, the Gulf Stream represents a virtually limitless wellspring of untapped energy. The Concept In the early 1990s, NASA conducted a three-year study to determine the feasibility of producing electricity from the Gulf Stream. Using standard Kaplan and Francis turbine designs, the same units used in the majority of traditional steam power plants, the agency found they were not able to produce enough electricity to compete cost-effectively with fossil fuel technology. This was due to a major design problem that prevented the technology from successfully transitioning to an ocean application.
The design problem resided in the fact that the turbines could not be scaled-up large enough to be cost-effective. In order to be cost-effective at the bottom of the ocean, a power system must be able to generate large quantities of electricity to offset the huge electrical equipment and cabling expenses. To produce a large amount of power, NASA needed a turbine much larger than those found in traditional steam power plants. Simply building a larger turbine was not an acceptable solution because the design of Kaplan and Francis turbines requires that the central shaft increase in size as the blades get longer and heavier. Because the central shaft and bearings are the most expensive part of the turbine, the overall cost would have outpaced the extra power output gained by building larger. Also, with this type of technology in the ocean, the torque produced to the shaft becomes unmanageable at about 15 meters (50 feet) in diameter due to the increased weight of the gearbox. Thus, NASA was limited to about one megawatt of power with an expensive centrally-shafted turbine, well outside the range of feasibility. With this in mind, Herbert Williams set out to design a machine specifically for ocean currents. Recognizing that scalability is the key to a successful power system, he began looking for structural ways to build larger without incurring crippling costs. Williams discovered the solution to scalability while attempting to design a more efficient blade.
A typical turbine uses a set of blades that works like an airplane propeller. Rotating around a central shaft, the majority of the power is generated near the tips of the blades. Very little power is produced near the center because rotation there equates to little relative blade motion. In fact, the shaft actually acts as a drag on power production because it causes turbulent fluid flow.
Williams envisioned that a perfect blade would use only the tips of the propellers. So, he began designing different blade configurations to maximize the most productive spot on the blade, the tip. However, simply adding more blades would not solve the problems of scalability and decreasing efficiency toward the center. Not only did this design eliminate the drag of the central shaft, but it also allowed Williams to add additional blade tips. In essence, the blade configuration he designed was a continuous series of only the most productive section of each blade. Williams soon came to realize that the ring-shaped blade design was also the answer to the problem of scalability. The reason for this is because no matter how large the contiguous circular blade is constructed, there is no cost burden associated with increasing the size of a central shaft. He also discovered that removing the central shaft greatly reduces the weight of the machine, making it easier and less expensive to transport and deploy.
To test the viability of the open-center concept, Herbert Williams constructed a small-scale prototype in 1995. He and a group of engineers conducted tests on the prototype, a 3-meter diameter blade, in the St. In order to confirm the viability of the concept, the engineers calculated that the prototype needed to generate 14 horsepower. It produced 17 horsepower, exceeding expectations and indicating a 20 to 25% power efficiency increase over commonly used Kaplan and Francis turbine blades. Shortly thereafter, a company interested in licensing the technology for the production of small (under 200 Kilowatts) turbines on rivers in Alaska performed an analysis of the design. Their computer model utilized existing blade shapes and included a "virtual" removal of the center mass of the turbine hub to simulate the open center concept. Their finding agreed with test results of the first prototype that the blade is approximately 22% more efficient.
Prompted by these findings, Williams built a second prototype in 2001 at a cost of approximately $250,000. This turbine was taken to the Atlantic Ocean and submersed for a series of tests with different blade configurations. The second prototype generated power directly from the Gulf Stream current and provided similar data as the first. Independent Evaluation Excited by the promise of a viable renewable technology, one of Florida's largest utility companies spent five months analyzing and testing the second prototype in 2002. The utility's test results were sufficient to merit a pledge of logistical support in commercializing the technology. However, market and Enron-related financial problems have plagued the company, making it an unlikely candidate for a strategic partnership. Nevertheless, intrigued by the Open-Center Turbine's displays of efficiency, the United States Naval Surface Warfare Center's Carderock Division examined the system in 2003 and subsequently agreed to pursue a Cooperative Research and Development Agreement (CRADA) to commercialize the technology. The CRADA requires Carderock to refine the entire system using the most sophisticated marine engineering technology in the world before testing and deploying a fully-operational underwater Open-Center Turbine power plant. Production Unit The production turbine is designed to produce 3 megawatts of electricity and is approximately 72 meters (240 feet) in length. It features two counter-rotating marine-resistant fiberglass blades, the larger being 323 meters (106 feet) in diameter. Each turbine will be deployed 60 meters (200 feet) underwater off the coast of Florida in a 140 square-mile area near Palm Beach County where the Gulf Stream makes its closest approach to land. There, sea tethers will anchor each machine in a manner similar to an oilrig, and a unique, patented flotation device will stabilize each unit. These turbines will incorporate buoyancy and anchoring systems, electrical generators, and transmission cables. Monitoring systems for pressure, temperature, vibration, RPM, and power output will be located on shore. Florida Hydro plans to place transmission cables beneath the seabed or along an existing pipeline to carry the electricity to shore where it will be fed into the nearest land-based electrical grid. Florida Hydro will install turbines in groups or clusters to make up a marine current farm, with a predicted density of up to 8 turbines per square mile. This is to avoid wake-interaction effects between the turbines and to allow for...
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