tag:blogger.com,1999:blog-1592992209402300549.post7797158911667067829..comments2024-03-28T08:06:43.198-04:00Comments on The Silicon Graybeard: Techy Tuesday - Potentially Useful Wind Turbines?SiGraybeardhttp://www.blogger.com/profile/00280583031339062059noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1592992209402300549.post-15100909454883631032014-07-03T18:11:00.344-04:002014-07-03T18:11:00.344-04:00Daniel_day - thanks for the info, updates and corr...Daniel_day - thanks for the info, updates and corrections. <br /><br />Re: wind farms affecting the weather; chaos theory was derived from early attempts at long range weather prediction. Their realization that forecasts a week out were changed by far right decimal places - "sensitive dependence on initial conditions" - is what gave rise to the phrase "butterfly effect" (and you gotta admit Butterfly Effect is a much sexier phrase than Sensitive Dependence on Initial Conditions). That's the cliche' that a single butterfly flapping its wings in the Amazon jungle today causes it to rain in New York in two weeks. If that's even remotely true, wind turbines <b>have to be </b> affecting the weather! <br /><br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-43101984074206794172014-07-03T02:05:35.973-04:002014-07-03T02:05:35.973-04:00Graybeard, Betz's theory did *not* specify a r...Graybeard, Betz's theory did *not* specify a rotating airfoil. What he called it was an "actuator disk", neglecting the physical configuration of the "disk", and he assumed Bernoulli's theorem and mass preservation for the airflow up- and downstream of the disk. If I can run down a text in my collection (probably), I can email you scans of several pages of the derivation of his 16/27 limit.<br />As for wind as a primary energy source, I did a lot of reading about wind power in the past and I'm skeptical that any authority on wind power ever made such a claim. I've no doubt plenty of starry-eyed dreamers talked that way. As you said, wind is usually intermittent, and the places where it is more dependably available tend to be scenic locations (some coastal regions, for example) that few people are willing to spoil with wind turbines, or so distant from developed areas that transmission losses are unacceptable.<br />Since the power in wind is proportional to the cube of wind speed, I'm very skeptical about getting useful power flows from 2 or 3 mph winds.<br />A few years back, I saw an article saying that large wind turbines had actually affected the local weather (sorry, no link). This I would never have expected, since wind turbines only tap air flows in the first hundred or two meter thickness of the atmosphere, but the data was the data.<br />Turbines with blades behind the generator and tower ("downwind turbines") are often coned, and can re-orient themselves aero-mechanically when the wind changes direction. The downwind configuration seems to be only used for sizes up to a few tens of kW, though.daniel_dayhttps://www.blogger.com/profile/18399665251275194585noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-85936167341737533122014-07-02T19:12:06.135-04:002014-07-02T19:12:06.135-04:00Weetabix: as I understood it, Betz's theory di...Weetabix: as I understood it, Betz's theory didn't address the case that Archimedes is using. Betz's model was specifically a rotating air foil. The Archimedes approach requires a different model to determine maximum possible energy recovery. It's a different principle that Betz's model doesn't apply to. What I thought was the highlight was starting up without a starter motor, and yawing into the wind without a motor assist, both of those are efficiency improvements and get closer to making wind power more reasonable. <br /><br />To echo (or underline) anon from 2337 last night, wind turbines are currently boutique energy sources. SWPL sources. My bet is they'll never be a primary source because on a worldwide basis, the wind just doesn't blow 24/7/365. <br /><br />And I think it's an interesting thought experiment as to what would happen to worldwide weather should we ever be able to extract the majority of energy out of the wind. If that's even possible. <br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-16718120793894887792014-07-02T12:22:26.824-04:002014-07-02T12:22:26.824-04:00When someone claims to beat on old, established li...When someone claims to beat on old, established limit that's based on old, established science and theory, I surely would like to see some independent verification.<br /><br />Think about Betz's law: you can never get 100% because the air on the back side of the turbine has to go somewhere - either away, or into some compressed space (Betz disallows this). Either one of those destinations takes energy to put the "waste" air there. His model is ideal - no friction, no drag, no rotor.<br /><br />These new guys may be right. Maybe Betz's model was wrong. But they absolutely must have someone else be able to duplicate their results, and it would be nice if they could come up with an alternate to Betz's model to demonstrate why their turbine beats his limit.<br /><br />But even without a model, the results have to be independently verifiable. Are they?Weetabixhttps://www.blogger.com/profile/06106614092497408546noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-32586144890101278512014-07-02T09:14:26.636-04:002014-07-02T09:14:26.636-04:00Good find. Hopefully they keep improving.Good find. Hopefully they keep improving.Anonymoushttps://www.blogger.com/profile/04245345365265060881noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-49783053605665090102014-07-01T23:37:04.830-04:002014-07-01T23:37:04.830-04:00Wind and PV electric generation is simply ineffici...Wind and PV electric generation is simply inefficient. I will accept the claim that these designs are more efficient then previous designs but I will assume that they are still too inefficient to compete. The acid test it do these systems need subsidies to survive. If they need tax breaks, direct subsidies or loan guarantees then the design/concept isn't practical. Simple as that. Anonymousnoreply@blogger.com