Denmark: High In the Sky

Sunday! Usually a day of rest in the U.S., that is not so here at the summer school. After the party last night (see the previous post), we all woke far too early this morning for a 7:30am breakfast and an 8am bus ride to a real working Vestas wind turbine. It was part of a wind 'farm,' set up on the property of a wheat farm (one of the farmers was out turning over the wheat clippings with a big machine; up a row and down another, back and forth). There were evergreens and oak trees ringing the field, and other turbines could be seen all around, off into the distance of the flattened landscape.

The turbine we visited is still in operation, though its design model was discontinued some ten years ago due to production costs being too high. It's 60 meters tall (to the nacelle, the motors and generator hub connected to the rotor) and the rotor blades are each 30 meters long. In groups of two, we ascended the inside of the tower in a small cage lift that wobbles and shakes if you even shift your weight a little. It's not that it's old and rickety, it's that there is only one thin cable holding it between top and bottom. You have to hold a button down and up to make it move. I went up with one of the other American students, Amy, and when we reached the nacelle, one of the Danish technicians was there to show us around. Beneath the main generator and rotor shaft chamber, there are two huge plastic and metal cubes holding 600 liters of water each. These are to dampen any vibrational motion caused by wind buffeting the tower or any mechanical shaking from the generator components. Up in the nacelle we looked at the yaw and pitch mechanisms, the main shaft chamber, the generator, and the transformer (all huge machines in a room about 8 meters by 4 meters. The highlight of the tower climb was being able to poke our heads out the top access hatch and take pictures from 60 meters high. We could see many many farms rolling into the distance, and many wind turbines dotting the land. Off to the east was the sea, about 10 km away, and, to the south we could see where they were Vestas workers were erecting a new wind turbine. This one will be the largest in the region, standing over 100 meters high to the nacelle and have blades that are 50 meters long.

We ate lunch at the turbine and then got back on the bus and traveled to a wind turbine blade factory, operated by a competing company, Siemens. You may have heard of this company because they have many industries from medical science to petroleum/fossil fuel refinement to information technology, and, for our visit, wind. The factory is in the northern part of Jutland (the part of Denmark connected to Germany that sticks out of mainland Europe like a thumb), close to the town of Ållborg. Two company engineers gave us some background information on the components and fabrication process of the wind blades, via powerpoint. They showed us some videos of how they test the blades for fatigue and extreme stress conditions. I thought this was the coolest video I've seen yet. They build a blade, fix it to a stand so it sticks out parallel to the ground, and attach a large clamp with a motor on it to the middle. This motor controls a shaft which has a swining weight attached to it. As the motor runs and the shaft turns, the weight flips around the shaft axis. Eventually, the whole blade is bending up and down and up and down, oscillating at its 'natural' frequency. They make it bounce 2 million times and call this treatment equivalent to 20 years of wind abuse. The guys said when one of these things snaps, it makes a sound like a cannon. I believe it; these things are giant pieces of fiber glass and epoxy, at lengths of 20 meters to 52 meters.

We were next taken to the production plants outside the office buildings. We were not allowed to take pictures (sorry guys), but the plant was amazing! As usual, the Danish are very meticulous about workplace safety, cleanliness, and order. They also have a neat, patented process for inserting the gallons and gallons of epoxy into the fiberglass and balsa wood frame. They build the frame in two pieces, a top and a bottom. Then they place both sides in a mold, with plastic bags lining the hollow interior. They pump down the mold to a vacuum and then flood the chamber with epoxy. After it cures, they pull the plastic out and you have a long hollow and very strong turbine blade. Next they paint it. We wanted to see the painting process, but, because it's a Sunday in Summer, that part of production was not in operation (they have a strange attitude towards days off here). I thought it was weird that they use balsa wood, the same light material found in those toy airplanes. But, apparently it's much cheaper than carbon fiber and holds up well enough to sell 7,000 turbines. We asked the technicians about carbon fiber and they said when (not if) the turbine blades get to 150 meters or so in length, it will become cost effective to use it, because the blades must be light enough so as not to overload the tower.

We returned from Ållborg to Fuglsøcentret around dinner time and, after eating, some of us went to the beach. I took my first swim in the Baltic Sea in my gym shorts. It was about as cold as Clear Creek in the beginning of the run-off season, cold enough to make me inhale a little sharply when I first submerged myself. The water is remarkably less salty than I expected; more of a hint than a sharp taste on the tongue. The sand is gray and there are many different colored rocks on the shoreline along with abundant sea weed and algae. I also found out, up close and personally, that Denmark has jellyfish. They are not deadly, but I swam right into one. It felt like a fragile sheet of plastic wrap brushing across my skin. Even as I type this, I can still feel the a little of the burning itchiness all over my abdomen and arms. One of the Danish students, Martin, assured me of the sting's mildness and said it would probably go away in a few hours. My skin turned red and bumpy, though I think I'll be just fine tomorrow. I cut my swim short after the stinging incident and skipped a few rocks before heading back to the center with the other students.

Some of us organized a futbol game in the gymnasium about an hour after the swim and I played until late with a dozen of them. I was the worst guy out there, but I still had a lot of fun. It's a great sport, even indoors. I actually scored one goal before the end.

Now, I'm sitting here at 12:15 on the morning of August 18. I have so much more to tell, but I am exhausted. I'm off to grab another beer and then to bed. Tomorrow I'll get back to the other days and tell you all about the other days (their posts will appear in order of day though, so look backwards).

Afskend!