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3.2 - First Modern Turbines & Large Prototypes – WIND TURBINES & WIND POWER

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3.2 - First Modern Turbines & Large Prototypes – WIND TURBINES & WIND POWER 3.2 - First modern turbines & large prototypes – WIND TURBINES & WIND POWER Produced by www.speechtotextservice.com Unchecked and not proof-read by the teacher Miroslav: Hello, and welcome back to the Renewable Energy Technology course. This is the lecture series on Wind Turbines. I am Miro, and we are at the third lecture, just some history, development timeline, and soft issues related to wind power and wind power development. The second part for the lecture will focus on the first modern large prototype wind turbines. Not really the commercial ones yet, but these were really the machines that created, or delivered the development, and it is very nice to learn to appreciate actually what people did and how they failed, because this is what actually helped to produce the modern development. One of the iconic machines from that time is exactly this one. We will come soon to it. Well, let’s start with the multi-blade windpumps. We are not going to talk about them a lot today. The other teacher for wind power in this course will stop longer at the windpumps. But we should mention that definitely, this was the first step towards the modern age of wind power. Moving from the four-bladed classic windmill rotor from the Middle Ages towards the industrial time, the link in between is exactly this type of machine. Very robust, very simple, very tough, very reliable design, with the main purpose to pump water, usually with a piston, a long piston plunging pump filling in a kind of a tank, just a reservoir, just beside the mill, usually used in, open, arid, windy and waterless places. Very good help for the colonial times in the new world, and if you go there, you can still see some of those machines just left there for the stupid tourists. Of course, we immediately notice that there is no pump here, but that’s how everything looks like. This thing can still work, if you really want it. There is nothing much to break. The blades are just curved plates. It can start while loaded and it is so simple that anybody could do it, or at least maintain it, or produce it. Then we move on to the first attempt to produce electricity, and it’s really a timeline here, or a turning point in wind turbine engineering. Back to the classic four-bladed rotor because that was the only thing that was known at that time, we’re talking about the beginning of the 20th century, and a Danish guy with a peculiar name of Poul La Cour, who actually managed to build this, who was teacher in rural Denmark in a vocational school for farmers. He was using this, a kind of a lab, to teach his students in smithing skills. They were supposed actually to be farm smiths, so to say, workshop technicians, and they were supposed to be able to handle everything. Plus, at that time, Europe was already developing while Denmark was without any fossil fuel resources, completely deforested -- we’re talking about more than a hundred years ago -- and wind stricken. Very poor in the country side and rural territories, and people actually needed to use any kind of energy possible for any purpose possible. Many of Poul La Cour’s students actually went on, including their sons and grandsons, to produce their own modern designs of small-scale windmills. Some of them actually participated in the modern age, in the middle of the 20th century into the really industrial development of wind turbines. 1 3.2 - First modern turbines & large prototypes – WIND TURBINES & WIND POWER Produced by www.speechtotextservice.com Unchecked and not proof-read by the teacher Poul La Cour even attempted water electrolysis, more than a hundred years ago -- we’re still talking about water electrolysis, nobody is really doing it -- with hydrogen storage. Hydrogen was interesting for the time for lighting. Nobody was driving engines on it. Lighting and heating, of course. It was used inside the school, in the lab there actually, by all the students. Poul La Cour was so famous at the time that Albert Betz in the 20’s, in Germany, he was a professor in the Technical University of Berlin -- was using Poul La Cour’s name, and was giving him as a good example to his own students on what can be done just with common mechanical engineering knowledge, without being a professor, and so on, and how can wind turbines be improved at the time. Well, after Poul La Cour, all the theories of aerodynamics was developed, at the time when aviation, modern aviation, and the theory of wing profiles, propellers and so on, was developed. After that, really, the modern wind turbines came to life and the first one of the really large size using proper airfoil blades -- you can see actually, the wing profile here, and it does look like a simple airplane wing -- was a turbine in Vermont, in the United States, in 1940. It was put in operation-- and actually managed to operate for quite some time -- by two guys. These are the two family names of the guys. You can check actually the text on your own. I have put a lot of text, it’s very explanatory, and tells the whole story on itself. Actually, those guys managed to produce a 53-meter rotor diameter. That would be more than 25-meter blade, a big achievement for the time. Of course, the blade wasn’t optimum. It was not twisted, definitely not tapered, and certainly not optimal for the application. It was a downwind machine. These two guys actually triggered a trend toward the conception of that the downwind style -- the wind comes from here, and hit’s the blades after the tower -- is a more reliable self-yawing or more sustainable, let’s say, or resisting to vibrations, and so on. Actually, it’s exactly the opposite. They had a 1 megawatt asynchronous generator and it actually worked. Then, we come to one of the most iconic devices of the modern time. In the 50’s -- this turbine survived until the 70’s, even until the 80’s it was still there and was able to operate. Not that big. 200 Kilowatts turbine, in Gedser, in the southern tip of Denmark, with a 24-meter rotor, developed by another iconic name -- and another strange and peculiar Danish name -- Johannes Juul, who was an utility engineer and was very well schooled in exactly aerodynamics and grid connection and power engineering, everything that was necessary, actually, to put together a modern wind turbine. You can easily notice now the very proper engineered blades. Each section is actually dimensioned the way it should be. Still, in terms of mechanical construction, those blades were made more or less by hollow aluminum, or some kind of metal parts welded together. Johannes Juul easily noticed that the blades are not able -- not reliable enough -- they are not able to sustain all kinds of vibrations that they were loaded with. They were prone to fatigue vibrations that were completely destroying everything else in the mechanical structure, and so on. But still, he was the first to define the three-bladed upwind, stall-controlled -- you see now, the first flap tip for the aerodynamic break -- 2 3.2 - First modern turbines & large prototypes – WIND TURBINES & WIND POWER Produced by www.speechtotextservice.com Unchecked and not proof-read by the teacher design for the time, which actually lived long enough to be the first ever commercial turbine later on. It was the first possible commercial turbine, exactly this type of design. Johannes Juul worked with this turbine for a long time. He actually managed to improve it a lot, measured a lot around it, even stiffened the rotor with this very funky arrangement here. It’s just a pole protruding from the hub, straight ahead, and then a wire mesh connected from the pole towards all the blades, mechanically stiffening and making them a bit more resistant to vibrations. Especially with the blades and the electrical parts inside the machine, Johannes Juul was improving a lot, and actually came up exactly with the modern, so-called “Danish concept” windmill, that managed to start the commercial reality of wind power. Another very good Danish example, switching back to downwind type, but still a three- bladed rotor, now with the first ever glass fiber blade, even if in the 70’s they were still very new and experimental. Actually, these blades were changed once, maybe twice. The so-called TVIND turbine in the Western coast of Denmark, was built by a group of enthusiasts. It was not at all state funded -- maybe it was, but at least the story says so. It had a 2 megawatt generator, the largest for the time -- we’re talking about the 70’s and the whole design, the whole project started in the 60’s -- and a 52-meter rotor. This was the first ever modern blades with modern materials that were attempted, and they proved to be very reliable. Well, quite expensive, concrete-built towers. Otherwise, everything else inside was the typical Danish concept of stall-controlled, squirrel cage, short-circuited induction generator, a very robust machine. Then, we are switching to other very interesting projects. We don’t have time actually to mention all of them. There are plenty of those, several in the United States, and in each of the industrialized countries, there was at least one of such large prototype of wind turbine.
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