=========================================================================== BBS: the Crystal Mountain BBS Date: 05-04-92 (16:53) Number: 3518 From: LAWRENCE LONDON Refer#: NONE To: KEITH ROGERS Recvd: NO Subj: wind power Conf: (33) Sust.Ag. --------------------------------------------------------------------------- Article 7027 (67 more) in sci.energy: From: Sherwood Botsford Subject: Re: Darrius wind turbines (was Re: Off-shore wind power Date: 23 Apr 92 17:44:29 GMT One thing I've yet to see is a Darrias rotor with a Savronius rotor perched at the top, or along the axis. Sized appropriately, this would make the whole assembly self starting, with a minor decrease in efficiency. As I recall doing some research on S rotors, using hemi-cylinders, they max out at about 35% efficiency. Don't recall if that's 35% of the 65% max theory efficiency, or 35% of total energy present. Considering how much easier they are to make for the home owner, building twice as many wouldn't be unreasonable. One means of emergency braking a vertical axis turbine is to have the axis extend below the pto for the generator and spin a paddle in a large tank. When Rpm exceeds a certain point, the tank is filled with water. As long as your shaft is strong enough to withstand the torque, this will still allow power generation during a gale. For really clever usage, you could regulate the level of water. All that extra energy gets converted into heat; Insulate the tank, and use wind generated hot water. (100% shaft-power -> heat conversion. Not quite, but close) Article 7044 (66 more) in sci.energy: From: Valerie Maslak Subject: Came in late in the wind discussion Date: 25 Apr 92 01:40:38 GMT I came in late in a topic I'm very interested in: wind energy. If by any remote chance anyone has been archiving this line of discussion, I'd really appreciate a copy. Otherwise, I have some questions. I read an article recently about a company in Rinkoeping, Denmark, that was a heavyweight in wind energy consulting. Does anyone have the name and address of this company? If not, who or what is the best source of info about medium-tech commercial or large-scale home systems? What exactly are the cost figures for wind energy production these days? What's the approximate cost per kilowatt for some of the systems now available? What are typical top and optimal wind speeds? What would expected buy-in costs be? Does anyone know of any major installations of commercial wind-energy production in the Third World, particularly in marine (seaside) environments? What sort of equipment is needed to feed from wind power into a generator-powered municipal system? Does anyone have a bibliography on commercial/residential wind (and solar) energy equipment? Any and all info appreciated. Valerie Maslak (may be interested in becoming an energy entrepreneur) Article 7048 (65 more) in sci.energy: Subject: Wind Turbines Date: 24 Apr 92 22:12:17 GMT The University of Massachusetts' ESI-80 machine is primarily a research tool but it does have a market for all it will produce. It is located adjacent to a large ski resort that will purchase the electricity for snow making and water slides in the summer. Areas of research are in control theory, instrumentation, wind/diesal power systems, and materials and mechanics in wind turbine construction. > Teetered hub? What? A teetered hub is one with the blades pivoting at the hub instead of ridgidly attached. This reduces some of the dynamic loads on the blade as it rotates through 360 degrees. > How will you "aim" it? The ESI-80 is currently a free yawing machine. The blades are downwind and the blades steer the naccelle as the wind changes. This can cause an average yaw error of 13 degrees off of wind line in some cases. This means less energy captured. Plans are in the works for an actively steered mechanism. This is a control problem involving when to steer it and with what type of drive control. The turbine weighs in at around 13000 pounds, a bit of mass to move smoothly and stop at a desired point. > How do you make your blades? How difficult/expensive is that? The blades are made by a commercial firm which makes the majority of wind turbine blades used in USA. They are wood/epoxy blades. They are very expensive, and thus the subject of much research on how to protect the machine in high winds or in wind shear conditions. > Aren't these the main advantages of wind power over the oceans: > Plenty of space, to facilitate commercial-scale expansion. > Steadier, more predictable wind over a large area, also for expansion. > A uniform construction platform. Thus, floating platforms could be build > on land and anchored out there without evaluating the cite. Europe has done the most off-shore wind farms and these are not really far off shore. Two factors come to play. Survivability, These machines are living on the edge on shore. The expected life of a machine is perhaps 15, 20 years. Off shore presents a whole lot of problems. Those who live on the ocean know what a price it can extract an tiny little machines that men put up. Another problem is getting the power ashore and into the grid. > WATER IS FLEXIBLE. > OK. Let me explain why I think that is so important: > If the wind turbines (any variety for now) were on floating platforms, > anchored to, say, a big chunk of concrete on the sea floor; the wind > would always push the turbine away from the wind's source. Could that > be used to aim the turbine, since it will always swing to face the > wind head on? Costal winds tend to be bi-directional with out much variation. Elaborate schemes to aim the machine are not really needed. They can be fixed and merely shut down when the wind does go off. By running the machine only in optimum winds you maximize output and minimize wear and tear on the machine, thus extending service. Also note. .. Ocean currents do not follow the wind and would steer the platforms at random. > Now, imagine a darrius-type turbine, BUT TURNED IN IT'S SIDE. On either > end of the axle would be a tower. The two towers, if not only by the axle, > would be structually connected. The towers would each be connected to the > a.... > Transmission equipment will be enormous, since the turbine's RPM will be > so low and torue will be so high. What can alleviate this? Low-RPM > generators? High-radius generators? But that would neccecitate deveolping > new generators, wouldn't it (bad news)? > Will there be This is the norm in wind power. The blades rotate at low speeds ( seventy something rpm perhaps ) and the generators run at 1750 RPM. Gear boxes are one of the major expenses in wind turbines. Many machines derive their frequency control of the AC output mechanically by the speed of the generator. This of course makes the demands on the drive train even more stringent. > Could the self-aiming property of bouyant platforms be used with > conventional HAWT's? Perhaps we could make them much larger if we > didn't need the aiming system, and could support the axle on BOTH ends > of the hub. Still, though, would my idea let us absorb a higher cross- > section of wind (rectangular, instead of circular). One should consider that having all your resources in one huge machine