BLADEcontrol technology from Bosch Rexroth analyzes the natural oscillations of the wind turbine blade. The frequencies of any blade are a unique pattern, like a fingerprint, in the range up to approximately 350Hz.
Of course one first looks at one's site to see what resources, demands one has. If one doesn't have a clue, one asks, pays for help or learns or both. If it is a bad WG site, then don't do that!!
I'm a fan of the local WG factory building, installing and maintaining them to avoid the problems you mentioned as has to do it right or go out of business. WG's don't play and if not done right, won't work long, weeks at best.
But done right ,many have lasted since the 30's, they can last near forever. The one Admiral Byrd put at his base camp is still running 80 yrs later saving tons of expensive to ship in diesel and pollution that not only pollutes but messes up their readings, experiments, etc.
A few issues with small units. I know you're an enthusiast, and already sold on them. Please try to see the issue from a home-owner's or home-buyer's point of view.
- Say I'm buying a place with a WT. They're unfamiliar to me. Seems like buying a used car (another piece of expensive machinery). This thing means paying more for the home. What's it worth to me? Does it provide lots of power or is it eco-bling, a WT in a low-wind valley?
- How do I know whether something's wrong with it? How do I maintain it? Did the previous owner do good maintenance, no maintenance, or the equivalent of putting sawdust in a noisy transmission?
- Is it safe? Could it fall on the house in a windstorm? Will the neighborhood kids climb it, fall, and I'll get sued? What if a blade comes off?
- What if it breaks? My kids are sick, my project is late, my boss is upset at me, carvs making a funny noise, it's sleeting and now my wife calls from the neighbor's house to tell me the lights went out. So the furnace is out too. (I'm an EE with tools and mechanical skills, and know how to fix many things. Most people aren't engineers). Who can fix this thing, when, and what'll it cost me?
People only have so much time and attention.
Whether you can get a check depends on which state you are in for home, building size units.
small WT's in the 2-5kw sizes are very cost effective because they can cost less and easily cover the energy needed by an eff home on many cases. A 1500sq' home can easily run on a 2kw WT in average US conditions.
Hydrualics are a joke in this as they are not eff at all mostly under 50% eff, killing them vs 95% eff gears or 100% eff direct drive with no gearing. And a 2Mw radiator to get rid of the waste heat farther adds to the cost.
It's a really interesting idea Cabe. The physical size/diameter of the direct drive generators is typically much larger, but perhaps you keep only the tower and rotor (both very expensive) and replace the entire nacelle. It might work out that the tower fatigue life is close to the 20 year turbine design life even though the ultimate strength is the overriding design factor. It's been a few years since I took a tower design class so I'm not certain about that. Either way I'm sure people would be willing to invest in an upgrade (risking a tower fatigue failure) so long as there was a good value proposition. This assuming in 10-15 years we don't have towers collapsing frequently due to fatigue failures.
A small but large network of turbines is the future? That sounds like a good idea. The question now, can older/smaller/OEM turnbine be upgraded to modern gearless standards? If not, that could be a niche market for expansion.
I am in the industry and there are hydraulic drivetrain concepts and prototype turbines out there. Another touted advantage is putting the electrical generator on the ground. The reason this is not mainstream is the mechanical efficiency losses. A hydraulic drivetrain can peak in the 80's (%) while a gearbox operates above 95% efficiency. There is a lot of talk about gearboxes and failures because there are a lot of geared machines out there, but the industry is moving away from them. Both Siemens and GE (and others) are shipping >3MW direct drive machines these days. Purpose built low speed PM generators are now the most reliable and efficient way to convert wind to electricity.
Oh, and comment about residential turbines: Smaller turbines are more difficult to get a good return on because of their scale but there are midsize turbines (~50kW-500kW) that can provide good ROI in areas that have a decent wind resource coupled with high electricity costs. You can sell power to utilities if your state has a net metering law. google 'net metering' or look on 'windpoweringamerica.gov' to research using wind in your area. These turbines are too large still for the average home/property.
Below is link to web page that illustrates the advantages and approach to using either hydraulics or electromechanical systems for blade pitch control.
The suppliers are split between offering hydraulic and electromechanical solutions with some companies like Moog offering both. The high power density and simplicity of fluid power keeps it in the game.
It is quite likely that a small portion of the hydraulic fluid from the power transfer lop could indeed be utilized for the other functions of blade pitch control and nacelle rotation. Of course it does come to mind that there are two typs of conditions where that may not work, which are during a shutdown (to avoid storm winds) period of no rotation, and when the wind was so slow that it would not turn the turbine blade. Of course, there could be hydraulic accumulators to provide backup for a while, and there could also be a backup pump running from auxilliary power. Other than that, there is no immeadiately obvious reason why not.
Now that the concept is published, perhaps some organization could run with it.
The engineers and inventors of the post WWII period turned their attention to advancements in electronics, communication, and entertainment. Breakthrough inventions range from LEGOs and computer gaming to the integrated circuit and Ethernet -- a range of advancements that have little in common except they changed our lives.
Neil Fromer is the executive director of the Resnick Institute, a program for energy and sustainability at the California Institute of Technology, working to develop new ideas and research technologies related to providing a sustainable future. He spoke to us about the severity of the current drought in California and how solar energy can help prevent such situations in the future.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.